Table Of Contents
bgp client-to-client reflection
default-information originate (BGP)
default-information originate (EGP)
default-information originate (IS-IS)
default-information originate (OSPF)
default-metric (BGP, EGP, OSPF, and RIP)
default-metric (IGRP and Enhanced IGRP only)
ip dvmrp routehog-notification
ip igmp query-max-response-time
ip rip authentication key-chain
neighbor (EGP, EIGRP, IGRP, RIP)
neighbor advertisement-interval
neighbor peer-group (assigning members)
neighbor peer-group (creating)
neighbor route-reflector-client
neighbor soft-reconfiguration inbound
network (IGRP and Enhanced IGRP)
show ip ospf retransmission-list
show ip rsvp interface installed
IP Routing Protocols Commands
Cisco's implementation of the Internet Protocol (IP) suite provides all major services contained in the Transmission Control Protocol (TCP)/IP specifications.
Use the commands in this chapter to configure and monitor the IP routing protocols. For IP routing protocol configuration information and examples, refer to the "Configuring IP Routing Protocols" chapter of the Network Protocols Configuration Guide, Part 1.
accept-lifetime
To set the time period during which the authentication key on a key chain is received as valid, use the accept-lifetime key chain key configuration command. To revert to the default value, use the no form of this command.
accept-lifetime start-time {infinite | end-time | duration seconds}
no accept-lifetime [start-time {infinite | end-time | duration seconds}]Syntax Description
Default
Forever (Starting time is January 1, 1993, and ending time is infinite.)
Command Mode
Key chain key configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Only RIP Version 2 uses key chains.
Specify a start-time and one of the following: infinite, end-time, or duration seconds.
We recommend running NTP or some other time synchronization method if you assign a lifetime to a key.
If the last key expires, authentication will continue and an error message will be generated. To disable authentication, you must manually delete the last valid key.
Examples
The following example configures a key chain called trees. In this example, the software will always accept and send willow as a valid key.
interface ethernet 0ip rip authentication key-chain treesip rip authentication mode md5!router ripnetwork 172.19.0.0version 2!key chain treeskey 1key-string willowIn the following example, the key chestnut will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key birch will be accepted from 2:30 p.m. to 4:40 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or discrepancies in the router's set time. There is a half hour leeway on each side to handle time differences.
interface ethernet 0ip rip authentication key-chain treesip rip authentication mode md5!router ripnetwork 172.19.0.0version 2!key chain treeskey 1key-string chestnutaccept-lifetime 13:30:00 Jan 25 1996 duration 7200send-lifetime 14:00:00 Jan 25 1996 duration 3600key 2key-string birchaccept-lifetime 14:30:00 Jan 25 1996 duration 7200send-lifetime 15:00:00 Jan 25 1996 duration 3600Related Commands
key
key chain
key-string
send-lifetime
show key chainaggregate-address
To create an aggregate entry in a BGP routing table, use the aggregate-address router configuration command. To disable this feature, use the no form of this command.
aggregate-address address mask [as-set] [summary-only] [suppress-map map-name]
[advertise-map map-name] [attribute-map map-name]
no aggregate-address address mask [as-set] [summary-only] [suppress-map map-name]
[advertise-map map-name] [attribute-map map-name]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can implement aggregate routing in BGP either by redistributing an aggregate route into BGP or by using this conditional aggregate routing feature.
Using the aggregate-address command with no arguments will create an aggregate entry in the BGP routing table if there are any more-specific BGP routes available that fall in the specified range. The aggregate route will be advertised as coming from your autonomous system and has the atomic aggregate attribute set to show that information might be missing. (By default, the atomic aggregate attribute is set unless you specify the as-set keyword.)
Using the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword, but the path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized. Do not use this form of aggregate-address when aggregating many paths, because this route must be continually withdrawn and re-updated as autonomous system path reachability information for the summarized routes changes.
Using the summary-only keyword not only creates the aggregate route (for example, 193.*.*.*) but will also suppress advertisements of more-specific routes to all neighbors. If you only want to suppress advertisements to certain neighbors, you may use the neighbor distribute-list command, with caution. If a more specific route leaks out, all BGP speakers will prefer that route over the less-specific aggregate you are generating (using longest-match routing).
Using the suppress-map keyword creates the aggregate route but suppresses advertisement of specified routes. You can use the match clauses of route maps to selectively suppress some more specific routes of the aggregate and leave others unsuppressed. IP access lists and autonomous system path access lists match clauses are supported.
Example
In the following example, an aggregate address is created. The path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized.
router bgp 5aggregate-address 193.0.0.0 255.0.0.0 as-setRelated Commands
match as-path
match ip address
route-maparea authentication
To enable authentication for an OSPF area, use the area authentication router configuration command. To remove an area's authentication specification or a specified area from the configuration, use the no form of this command.
area area-id authentication [message-digest]
no area area-id authentication
no area area-idSyntax Description
Default
Type 0 authentication (no authentication)
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The message-digest keyword first appeared in Cisco IOS Release 11.0.
Specifying authentication for an area sets the authentication to Type 1 (simple password) as specified in RFC 1247. If this command is not included in the configuration file, authentication of Type 0 (no authentication) is assumed.
The authentication type must be the same for all routers and access servers in an area. The authentication password for all OSPF routers on a network must be the same if they are to communicate with each other via OSPF. Use the ip ospf authentication-key command to specify this password.
If you enable MD5 authentication with the message-digest keyword, you must configure a password with the ip ospf message-digest-key command.
To remove the area's authentication specification, use the no form of this command with the authentication keyword. To remove the specified area from the software configuration, use the command no area area-id (with no other keywords).
Note
To remove the specified area from the software configuration, use the command no area area-id (with no other keywords). That is, no area area-id removes all area options, such as area authentication, area default-cost, area nssa, area range, area stub, and area virtual-link.
Example
The following example mandates authentication for areas 0 and 36.0.0.0 of OSPF routing process 201. Authentication keys are also provided.
interface ethernet 0ip address 131.119.251.201 255.255.255.0ip ospf authentication-key adcdefgh!interface ethernet 1ip address 36.56.0.201 255.255.0.0ip ospf authentication-key ijklmnop!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0network 131.119.0.0 0.0.255.255 area 0area 36.0.0.0 authenticationarea 0 authenticationRelated Commands
area default-cost
area stub
ip ospf authentication-key
ip ospf message-digest-keyarea default-cost
To specify a cost for the default summary route sent into a stub area, use the area default-cost router configuration command. To remove the assigned default route cost, use the no form of this command.
area area-id default-cost cost
no area area-id default-cost cost
no area area-idSyntax Description
Default
Cost of 1
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The command is used only on an area border router attached to a stub area.
There are two stub area router configuration commands: the stub and default-cost options of the area command. In all routers and access servers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an area border router attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.
Note
Example
The following example assigns a default-cost of 20 to stub network 36.0.0.0:
interface ethernet 0ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 stubarea 36.0.0.0 default-cost 20Related Commands
area nssa
To configure an area as a not so stubby area (NSSA), use the area nssa router configuration command. To remove the nssa distinction from the area, use the no form of this command.
area area-id nssa [no-redistribution] [default-information-originate]
no area area-id nssa
no area area-idSyntax Description
Default
No NSSA area is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Note
Example
In the following example, NSSA authentication is enabled on area 1:
router ospf1redistribute rip subnetsnetwork 172.19.92.0.0.0.0.255 area 1area 1 nssaarea-password
To configure the IS-IS area authentication password, use the area-password router configuration command. To disable the password, use the no form of this command.
area-password password
no area-password [password]Syntax Description
Default
No area password is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This password is inserted in Level 1 (station router level) link state PDUs (LSPs), complete sequence number PDUs (CSNPs), and partial sequence number PDUs (PSNP).
Example
The following example assigns an area authentication password:
router isisarea-password angelRelated Command
area range
To consolidate and summarize routes at an area boundary, use the area range router configuration command. To disable this function, use the no form of this command.
area area-id range address mask [advertise | not-advertise]
no area area-id range address mask [advertise | not-advertise]
no area area-idSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The area range command is used only with area border routers (ABRs). It is used to consolidate or summarize routes for an area. The result is that a single summary route is advertised to other areas by the ABR. Routing information is condensed at area boundaries. External to the area, a single route is advertised for each address range. This is called route summarization.
Multiple area router configuration commands specifying the range option can be configured. Thus, OSPF can summarize addresses for many different sets of address ranges.
Note
Example
The following example specifies one summary route to be advertised by the ABR to other areas for all subnets on network 36.0.0.0 and for all hosts on network 192.42.110.0:
interface ethernet 0ip address 192.42.110.201 255.255.255.0!interface ethernet 1ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0network 192.42.110.0 0.0.0.255 area 0area 36.0.0.0 range 36.0.0.0 255.0.0.0area 0 range 192.42.110.0 255.255.255.0area stub
To define an area as a stub area, use the area stub router configuration command. To disable this function, use the no form of this command.
area area-id stub [no-summary]
no area area-id stub
no area area-idSyntax Description
area-id
Identifier for the stub area. The identifier can be either a decimal value or an IP address.
no-summary
(Optional) Prevents an ABR from sending summary link advertisements into the stub area.
Default
No stub area is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You must configure the area stub command on all routers and access servers in the stub area. Use the area router configuration command with the default-cost option to specify the cost of a default internal router sent into a stub area by an area border router.
There are two stub area router configuration commands: the stub and default-cost options of the area router configuration command. In all routers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an ABR attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.
To further reduce the number of link state advertisements (LSA) sent into a stub area, you can configure no-summary on the ABR to prevent it from sending summary LSAs (LSA type 3) into the stub area.
Note
Example
The following example assigns a default cost of 20 to stub network 36.0.0.0:
interface ethernet 0ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 stubarea 36.0.0.0 default-cost 20Related Commands
area authentication
area default-costarea virtual-link
To define an OSPF virtual link, use the area virtual-link router configuration command with the optional parameters. To remove a virtual link, use the no form of this command.
area area-id virtual-link router-id [hello-interval seconds] [retransmit-interval seconds]
[transmit-delay seconds] [dead-interval seconds] [[authentication-key key] |
[message-digest-key keyid md5 key]]
no area area-id virtual-link router-id [hello-interval seconds] [retransmit-interval seconds]
[transmit-delay seconds] [dead-interval seconds] [[authentication-key key] |
[message-digest-key keyid md5 key]]
no area area-idSyntax Description
Defaults
area-id: No area ID is predefined.
router-id: No router ID is predefined.
hello-interval seconds: 10 seconds
retransmit-interval seconds: 5 seconds
transmit-delay seconds: 1 second
dead-interval seconds: 40 seconds
authentication-key key: No key is predefined.
message-digest-key keyid md5 key: No key is predefined.Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The following keywords and arguments first appeared in Cisco IOS Release 11.0: message-digest-key keyid md5 key.
In OSPF, all areas must be connected to a backbone area. If the connection to the backbone is lost, it can be repaired by establishing a virtual link.
The smaller the hello interval, the faster topological changes will be detected, but more routing traffic will ensue.
The setting of the retransmit interval should be conservative, or needless retransmissions will result. The value should be larger for serial lines and virtual links.
The transmit delay value should take into account the transmission and propagation delays for the interface.
The Cisco IOS software will use the specified authentication key only when authentication is enabled for the backbone with the area area-id authentication router configuration command.
The two authentication schemes, simple text and MD5 authentication, are mutually exclusive. You can specify one or the other or neither. Any keywords and arguments you specify after authentication-key key or message-digest-key keyid md5 key are ignored. Therefore, specify any optional arguments before such a keyword-argument combination.
Note
Note
Examples
The following example establishes a virtual link with default values for all optional parameters:
router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 virtual-link 36.3.4.5The following example establishes a virtual link with MD5 authentication:
router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 virtual-link 36.3.4.5 message-digest-key 3 md5 sa5721bk47Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
area authentication
service password-encryption †
show ip ospfautonomous-system (EGP)
To specify the local autonomous system that the Cisco IOS software resides in for EGP, use the autonomous-system global configuration command. To remove the autonomous system number, use the no form of this command.
autonomous-system local-as
no autonomous-system local-asSyntax Description
Default
No local autonomous system is specified.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Before you can set up EGP routing, you must specify an autonomous system number. The local autonomous system number will be included in EGP messages sent by the software.
Example
The following sample configuration specifies an autonomous system number of 110:
autonomous-system 110Related Command
auto-summary
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary router configuration command. To disable this feature and transmit subprefix routing information across classful network boundaries, use the no form of this command.
auto-summary
no auto-summarySyntax Description
This command has no arguments or keywords.
Default
Enabled (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Route summarization reduces the amount of routing information in the routing tables.
By default, BGP does not accept subnets redistributed from IGP. To advertise and carry subnet routes in BGP, use an explicit network command or the no auto-summary command. If you disable auto-summarization and have not entered a network command, you will not advertise network routes for networks with subnet routes unless they contain a summary route.
IP Enhanced IGRP summary routes are given an administrative distance value of 5. You cannot configure this value.
RIP Version 1 always uses automatic summarization. If you are using RIP Version 2, you can turn off automatic summarization by specifying no auto-summary. Disable automatic summarization if you must perform routing between disconnected subnets. When automatic summarization is off, subnets are advertised.
Examples
In the following example, network numbers are not summarized automatically:
router bgp 6no auto-summaryThe following example disables automatic summarization for process eigrp 109:
router eigrp 109no auto-summaryRelated Command
bgp always-compare-med
To allow the comparison of the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems, use the bgp always-compare-med router configuration command. To disallow the comparison, use the no form of this command.
bgp always-compare-med
no bgp always-compare-medSyntax Description
This command has no arguments or keywords.
Default
The Cisco IOS software does not compare MEDs for paths from neighbors in different autonomous systems.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
The MED is one of the parameters that is considered when selecting the best path among many alternative paths. The path with a lower MED is preferred over a path with a higher MED.
By default, during the best-path selection process, MED comparison is done only among paths from the same autonomous system. This command changes the default behavior by allowing comparison of MEDs among paths regardless of the autonomous system from which the paths are received.
Example
In the following example, the BGP speaker in autonomous system 100 is configured to compare MEDs among alternative paths, regardless of the autonomous system from which the paths are received:
router bgp 109bgp always-compare-medbgp client-to-client reflection
To restore route reflection from a BGP route reflector to clients, use the bgp client-to-client reflection router configuration command. To disable client-to-client reflection, use the no form of this command.
bgp client-to-client reflection
no bgp client-to-client reflectionSyntax Description
This command has no arguments or keywords.
Default
When a route reflector is configured, the route reflector reflects routes from a client to other clients.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
By default, the clients of a route reflector are not required to be fully meshed and the routes from a client are reflected to other clients. However, if the clients are fully meshed, route reflection is not required. Use the no bgp client-to-client reflection command to disable client-to-client reflection.
If client-to-client reflection is enabled, the clients of a route reflector cannot be members of a peer group.
Example
In the following example, the local router is a route reflector. The three neighbors are fully meshed, so client-to-client reflection is disabled.
router bgp 5neighbor 155.24.95.22 route-reflector-clientneighbor 155.24.95.23 route-reflector-clientneighbor 155.24.95.24 route-reflector-clientno bgp client-to-client reflectionRelated Commands
bgp cluster-id
neighbor route-reflector-client
show ip bgpbgp cluster-id
To configure the cluster ID if the BGP cluster has more than one route reflector, use the bgp cluster-id router configuration command. To remove the cluster ID, use the no form of this command.
bgp cluster-id cluster-id
no bgp cluster-id cluster-idSyntax Description
Default
The router ID of the single route reflector in a cluster
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Together, a route reflector and its clients form a cluster.
Usually a cluster of clients will have a single route reflector. In that case, the cluster is identified by the router ID of the route reflector. In order to increase redundancy and avoid a single point of failure, a cluster might have more than one route reflector. In this case, all route reflectors in the cluster must be configured with the 4-byte cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster.
If the cluster has more than one route reflector, use this command to configure the cluster ID.
Example
In the following example, the local router is one of the route reflectors serving the cluster. It is configured with the cluster ID to identify the cluster.
router bgp 5neighbor 198.92.70.24 route-reflector-clientbgp cluster-id 50000Related Commands
bgp client-to-client reflection
neighbor route-reflector-client
show ip bgpbgp confederation identifier
To specify a BGP confederation identifier, use the bgp confederation identifier router configuration command. To remove the confederation identifier, use the no form of this command.
bgp confederation identifier autonomous-system
no bgp confederation identifier autonomous-systemSyntax Description
Default
No confederation identifier is configured.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Another way to reduce the IBGP mesh is to divide an autonomous system into multiple autonomous systems and group them into a single confederation. Each autonomous system is fully meshed within itself, and has a few connections to another autonomous system in the same confederation. Even though the peers in different autonomous systems have EBGP sessions, they exchange routing information as if they are IBGP peers. Specifically, the next-hop and local preference information is preserved. This enables to you to retain a single Interior Gateway Protocol (IGP) for all the autonomous systems. To the outside world, the confederation looks like a single autonomous system.
Example
In the following example, the autonomous system is divided into autonomous systems 4001, 4002, 4003, 4004, 4005, 4006, and 4007 and identified by the confederation identifier 5. Neighbor 1.2.3.4 is someone inside your routing domain confederation. Neighbor 3.4.5.6 is someone outside your routing domain confederation. To the outside world, there appears to be a single autonomous system with the number 5.
router bgp 4001bgp confederation identifier 5bgp confederation peers 4002 4003 4004 4005 4006 4007neighbor 1.2.3.4 remote-as 4002neighbor 3.4.5.6 remote-as 510Related Command
bgp confederation peers
To configure the autonomous systems that belong to the confederation, use the bgp confederation peers router configuration command. To remove an autonomous system from the confederation, use the no form of this command.
bgp confederation peers autonomous-system [autonomous-system]
no bgp confederation peers autonomous-system [autonomous-system]Syntax Description
Default
No confederation peers are configured.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
The autonomous systems specified in this command are visible internally to a confederation. Each autonomous system is fully meshed within itself. The bgp confederation identifier command specifies the confederation to which the autonomous systems belong.
Example
The following example specifies that autonomous systems 1090, 1091, 1092, and 1093 belong to a single confederation:
router bgp 1090bgp confederation peers 1091 1092 1093Related Command
bgp default local-preference
To change the default local preference value, use the bgp default local-preference router configuration command. To return to the default setting, use the no form of this command.
bgp default local-preference value
no bgp default local-preference valueSyntax Description
Default
Local preference value of 100
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Generally, the default value of 100 allows you to easily define a particular path as less preferable than paths with no local preference attribute. The preference is sent to all routers and access servers in the local autonomous system.
Example
In the following example, the default local preference value is raised from the default of 100 to 200:
router bgp 200bgp default local-preference 200Related Command
bgp fast-external-fallover
To immediately reset the BGP sessions of any directly adjacent external peers if the link used to reach them goes down, use the bgp fast-external-fallover router configuration command. To disable this feature, use the no form of this command.
bgp fast-external-fallover
no bgp fast-external-falloverSyntax Description
This command has no arguments or keywords.
Default
Enabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
In the following example, the automatic resetting of BGP sessions is disabled:
router bgp 109no bgp fast-external-falloverclear arp-cache
To remove all dynamic entries from the ARP cache and to clear the fast-switching cache, use the clear arp-cache EXEC command.
clear arp-cache
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
The following example removes all dynamic entries from the ARP cache and clears the fast-switching cache:
clear arp-cacheclear ip bgp
To reset a BGP connection using BGP soft reconfiguration, use the clear ip bgp EXEC command at the system prompt.
clear ip bgp {* | address | peer-group name} [soft [in | out]]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
If you specify BGP soft reconfiguration, by including the soft keyword, the sessions are not reset and the router sends all routing updates again. To generate new inbound updates without resetting the BGP session, the local BGP speaker should store all received updates without modification regardless of whether it is accepted by the inbound policy. This process is memory intensive and should be avoided if possible. Outbound BGP soft configuration does not have any memory overhead. You can trigger an outbound reconfiguration on the other side of the BGP session to make the new inbound policy take effect.
Use this command whenever any of the following changes occur:
•
•
•
•
•
•
Example
The following example resets all current BGP sessions:
clear ip bgp *Related Commands
clear ip bgp peer-group
To remove all the members of a BGP peer group, use the clear ip bgp peer-group EXEC command.
clear ip bgp peer-group tag
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Example
The following example removes all members from the BGP peer group internal:
clear ip bgp peer-group internalRelated Command
neighbor peer-group (assigning members)
clear ip cgmp
To clear all group entries from the Catalyst switches' caches, use the clear ip cgmp EXEC command.
clear ip cgmp [type number]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
This command sends a CGMP Leave message with a group address of 0000.0000.0000 and a unicast address of 0000.0000.0000. This instructs the switches to clear all group entries they have cached.
If an interface type and number are specified, the Leave message is sent only on that interface. Otherwise, it is sent on all CGMP-enabled interfaces.
Example
The following example clears the CGMP cache:
clear ip cgmpRelated Command
clear ip dvmrp route
To delete routes from the DVMRP routing table, use the clear ip dvmrp route EXEC command.
clear ip dvmrp route {* | route}
Syntax Description
*
Clears all routes from the DVMRP table.
route
Clears the longest matched route. Can be an IP address, a network number, or an IP DNS name.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Examples
The following example deletes route 10.1.1.1 from the DVMRP routing table:
clear ip dvmrp route 10.1.1.1The following example deletes network 10.0.0.0 from the DVMRP routing table:
clear ip dvmrp route 10.0.0.0clear ip eigrp neighbors
To delete entries from the neighbor table, use the clear ip eigrp neighbors EXEC command.
clear ip eigrp neighbors [ip-address | type number]
Syntax Description
ip-address
(Optional) Address of the neighbor.
type number
(Optional) Interface type and number. Specifying these arguments removes from the neighbor table all entries learned via this interface.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
The following example removes the neighbor whose address is 160.20.8.3:
clear ip eigrp neighbors 160.20.8.3Related Command
clear ip igmp group
To delete entries from the IGMP cache, use the clear ip igmp group EXEC command.
clear ip igmp group [group-name | group-address | type number]
Syntax Description
Default
When the command is used with no arguments, all entries are deleted from the IGMP cache.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The IGMP cache contains a list of the multicast groups of which hosts on the directly connected LAN are members. If the router has joined a group, it is also listed in the cache.
To delete all entries from the IGMP cache, specify the clear ip igmp group command with no arguments.
Example
The following example clears entries for the multicast group 224.0.255.1 from the IGMP cache:
clear ip igmp group 224.0.255.1Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
ip host †
show ip igmp groups
show ip igmp interfaceclear ip mroute
To delete entries from the IP multicast routing table, use the clear ip mroute EXEC command.
clear ip mroute {* | group [source]}
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Examples
The following example deletes all entries from the IP multicast routing table:
clear ip mroute *The following example deletes from the IP multicast routing table all sources on the 10.3.0.0 subnet that are transmitting to the multicast group 224.2.205.42. Note that this example deletes all sources on network 10.3, not individual sources.
clear ip mroute 224.2.205.42 10.3.0.0Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
ip host †
show ip mrouteclear ip route
To remove one or more routes from the IP routing table, use the clear ip route EXEC command.
clear ip route {network [mask] | *}
Syntax Description
network
Network or subnet address to remove.
mask
(Optional) Network mask associated with the IP address you wish to remove.
*
Removes all entries.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
The following example removes a route to network 132.5.0.0 from the IP routing table:
clear ip route 132.5.0.0Related Command
clear ip sdr
To delete an sdr cache entry or the entire sdr cache, use the clear ip sdr EXEC command.
clear ip sdr [group-address | "session-name"]
Syntax Description
group-address
(Optional) Deletes all sessions associated with the IP group address.
"session-name"
(Optional) Deletes only the sdr cache entry with the specified name.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
If no arguments or keywords are used with this command, the system deletes the entire sdr cache.
Example
The following example clears the sdr cache:
clear ip sdrRelated Commands
ip sdr cache-timeout
ip sdr listen
show ip sdrdefault-information
To control the candidate default routing information between IGRP or Enhanced IGRP processes, use the default-information router configuration command. To suppress IGRP or Enhanced IGRP candidate information in incoming updates, use the no default-information in command. To suppress IGRP or Enhanced IGRP candidate information in outbound updates, use the no default-information allowed out command.
default-information {in | out} {access-list-number | name}
no default-information {in | out}Syntax Description
Default
Normally, exterior routes are always accepted and default information is passed between IGRP or Enhanced IGRP processes when doing redistribution.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The access-list-number and name arguments first appeared in Cisco IOS Release 11.2.
The default network of 0.0.0.0 used by RIP cannot be redistributed by IGRP or Enhanced IGRP.
Examples
The following example allows IGRP exterior or default routes to be received by the IGRP process in autonomous system 23:
router igrp 23default-information inThe following example allows IP Enhanced IGRP exterior or default routes to be received by the IP Enhanced IGRP process in autonomous system 23:
router eigrp 23default-information indefault-information originate (BGP)
To allow the redistribution of network 0.0.0.0 into BGP, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate
no default-information originateSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The same functionality will result from the network 0.0.0.0 command, using the network router configuration command.
Example
The following example configures BGP to redistribute network 0.0.0.0 into BGP:
router bgp 164default-information originatedefault-information originate (EGP)
To explicitly configure EGP to generate a default route, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate
no default-information originateSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Because EGP can use network 0.0.0.0 as a default route, EGP must be explicitly configured to generate a default route. If the next hop for the default route can be advertised as a third party, it will be included as a third party.
Example
The following example configures EGP to generate a default route:
autonomous system 109router egp 164network 131.108.0.0network 192.31.7.0neighbor 10.2.0.2default-information originatedefault-information originate (IS-IS)
To generate a default route into an IS-IS routing domain, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate [route-map map-name]
no default-information originate [route-map map-name]Syntax Description
route-map map-name
(Optional) Routing process will generate the default route if the route map is satisfied.
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
If a router configured with this command has a route to 0.0.0.0 in the routing table, IS-IS will originate an advertisement for 0.0.0.0 in its LSPs.
Example
In the following configuration, the Cisco IOS software is forced to generate a default external route into an IS-IS domain:
router isis! BGP routes will be distributed into IS-ISredistribute bgp 120! access list 2 is applied to outgoing routing updatesdistribute-list 2 outdefault-information originate! access list 2 defined as giving access to network 100.105.0.0access-list 2 permit 100.105.0.0 0.0.255.255Related Commands
default-information originate (OSPF)
To generate a default route into an OSPF routing domain, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]
no default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Whenever you use the redistribute or the default-information router configuration commands to redistribute routes into an OSPF routing domain, the Cisco IOS software automatically becomes an autonomous system boundary router (ASBR). However, an ASBR does not, by default, generate a default route into the OSPF routing domain. The software still must have a default route for itself before it generates one, except when you have specified the always keyword.
When you use this command for the OSPF process, the default network must reside in the routing table and you must satisfy the route-map map-name keyword. Use the default-information originate always route-map map-name form of the command when you do not want the dependency on the default network in the routing table.
Example
The following example specifies a metric of 100 for the default route redistributed into the OSPF routing domain and an external metric type of Type 1:
router ospf 109redistribute igrp 108 metric 100 subnetsdefault-information originate metric 100 metric-type 1Related Command
default-metric (BGP, EGP, OSPF, and RIP)
To set default metric values for the BGP, EGP, OSPF, and RIP routing protocols, use this form of the default-metric router configuration command. To return to the default state, use the no form of this command.
default-metric number
no default-metricSyntax Description
Default
Built-in, automatic metric translations, as appropriate for each routing protocol
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The default-metric command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.
In BGP, this sets the Multi Exit Discriminator (MED) metric. (The name of this metric for BGP Versions 2 and 3 is INTER_AS.)
Example
The following example shows a router in autonomous system 109 using both the RIP and the OSPF routing protocols. The example advertises OSPF-derived routes using the RIP protocol and assigns the OSPF-derived routes a RIP metric of 10.
router ripdefault-metric 10redistribute ospf 109Related Command
default-metric (IGRP and Enhanced IGRP only)
To set metrics for IGRP or Enhanced IGRP, use this form of the default-metric router configuration command. To remove the metric value and restore the default state, use the no form of this command.
default-metric bandwidth delay reliability loading mtu
no default-metric bandwidth delay reliability loading mtuSyntax Description
Default
Only connected routes and interface static routes can be redistributed without a default metric.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
A default metric is required to redistribute a protocol into IGRP or Enhanced IGRP, unless you use the redistribute command. Automatic metric translations occur between IGRP and Enhanced IGRP. You do not need default metrics to redistributed IGRP or Enhanced IGRP into itself.
Metric defaults have been carefully set to work for a wide variety of networks. Take great care in changing these values.
Keeping the same metrics is supported only when redistributing from IGRP, Enhanced IGRP, or static routes.
Example
The following example takes redistributed RIP metrics and translates them into IGRP metrics with values as follows: bandwidth = 1000, delay = 100, reliability = 250, loading = 100, and mtu =1500.
router igrp 109network 131.108.0.0redistribute ripdefault-metric 1000 100 250 100 1500Related Command
distance
To define an administrative distance, use the distance router configuration command. To remove a distance definition, use the no form of this command.
distance weight [address mask [access-list-number | name]] [ip]
no distance weight [address mask [access-list-number]] [ip]Syntax Description
Default
lists default administrative distances.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The access-list-name argument first appeared in Cisco IOS Release 11.2.
Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.
When the optional access list number is used with this command, it is applied when a network is being inserted into the routing table. This behavior allows filtering of networks according to the IP address of the router supplying the routing information. This could be used, as an example, to filter out possibly incorrect routing information from routers not under your administrative control.
The order in which you enter distance commands can affect the assigned administrative distances in unexpected ways (see the "Example" section for further clarification).
Weight values are also subjective; there is no quantitative method for choosing weight values.
For BGP, the distance command sets the administrative distance of the External BGP route.
The show ip protocols EXEC command displays the default administrative distance for a specified routing process.
Example
In the following example, the router igrp global configuration command sets up IGRP routing in autonomous system number 109. The network router configuration commands specify IGRP routing on networks 192.31.7.0 and 128.88.0.0. The first distance router configuration command sets the default administrative distance to 255, which instructs the Cisco IOS software to ignore all routing updates from routers for which an explicit distance has not been set. The second distance command sets the administrative distance for all routers on the Class C network 192.31.7.0 to 90. The third distance command sets the administrative distance for the router with the address 128.88.1.3 to 120.
router igrp 109network 192.31.7.0network 128.88.0.0distance 255distance 90 192.31.7.0 0.0.0.255distance 120 128.88.1.3 0.0.0.0Related Command
distance bgp
To allow the use of external, internal, and local administrative distances that could be a better route to a node, use the distance bgp router configuration command. To return to the default values, use the no form of this command.
distance bgp external-distance internal-distance local-distance
no distance bgpSyntax Description
Defaults
external-distance: 20
internal-distance: 200
local-distance: 200Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.
Use this command if another protocol is known to be able to provide a better route to a node than was actually learned via external BGP, or if some internal routes should really be preferred by BGP.
Note
Example
In the following example, internal routes are known to be preferable to those learned through the IGP, so the administrative distance values are set accordingly:
router bgp 109network 131.108.0.0neighbor 129.140.6.6 remote-as 123neighbor 128.125.1.1 remote-as 47distance bgp 20 20 200Related Command
distance eigrp
To allow the use of two administrative distances—internal and external—that could be a better route to a node, use the distance eigrp router configuration command. To reset these values to their defaults, use the no form of this command.
distance eigrp internal-distance external-distance
no distance eigrpSyntax Description
Default
internal-distance: 90
external-distance: 170Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.
Use the distance eigrp command if another protocol is known to be able to provide a better route to a node than was actually learned via external Enhanced IGRP or if some internal routes should really be preferred by Enhanced IGRP.
in the distance command section lists the default administrative distances.
To display the default administrative distance for a specified routing process, use the show ip protocols EXEC command.
Example
In the following example, the router eigrp global configuration command sets up Enhanced IGRP routing in autonomous system number 109. The network router configuration commands specify Enhanced IGRP routing on networks 192.31.7.0 and 128.88.0.0. The first distance router configuration command sets the default administrative distance to 255, which instructs the Cisco IOS software to ignore all routing updates from routers for which an explicit distance has not been set. The second distance router configuration command sets the administrative distance for all routers on the Class C network 192.31.7.0 to 90. The third distance router configuration command sets the administrative distance for the router with the address 128.88.1.3 to 120.
router eigrp 109network 192.31.7.0network 128.88.0.0distance 255!! use caution when executing the next two commands!!distance 90 192.31.7.0 0.0.0.255distance 120 128.88.1.3 0.0.0.0Related Command
distribute-list in
To filter networks received in updates, use the distribute-list in router configuration command. To change or cancel the filter, use the no form of this command.
distribute-list access-list-number | name in [type number]
no distribute-list access-list-number in [type number]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The access-list-name, type, and number arguments first appeared in Cisco IOS Release 11.2.
This command is not supported in IS-IS.
Example
In the following example, the Enhanced IGRP routing process accepts only two networks—network 0.0.0.0 and network 131.108.0.0:
access-list 1 permit 0.0.0.0access-list 1 permit 131.108.0.0access-list 1 deny 0.0.0.0 255.255.255.255router eigrpnetwork 131.108.0.0distribute-list 1 inRelated Commands
A dagger (†) indicates that the command is documented outside this chapter.
access-list (extended) †
access-list (standard) †
distribute-list out
redistributedistribute-list out
To suppress networks from being advertised in updates, use the distribute-list out router configuration command. To cancel this function, use the no form of this command.
distribute-list access-list-number | name out [interface-name | routing-process |
autonomous-system-number]
no distribute-list access-list-number out [interface-name | routing-process |
autonomous-system-number]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The access-list-name argument first appeared in Cisco IOS Release 11.2.
When redistributing networks, a routing process name can be specified as an optional trailing argument to the distribute-list command. This causes the access list to be applied to only those routes derived from the specified routing process. After the process-specific access list is applied, any access list specified by a distribute-list command without a process name argument will be applied. Addresses not specified in the distribute-list command will not be advertised in outgoing routing updates.
Note
Examples
The following example would cause only one network to be advertised by a RIP routing process: network 131.108.0.0.
access-list 1 permit 131.108.0.0access-list 1 deny 0.0.0.0 255.255.255.255router ripnetwork 131.108.0.0distribute-list 1 outIn the following example, access list 1 is applied to outgoing routing updates and IS-IS is enabled on Ethernet interface 0. Only network 131.131.101.0 will be advertised in outgoing IS-IS routing updates.
router isisredistribute ospf 109distribute-list 1 outinterface Ethernet 0ip router isisaccess-list 1 permit 131.131.101.0 0.0.0.255Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
access-list (extended) †
access-list (standard) †
distribute-list in
redistributedomain-password
To configure the IS-IS routing domain authentication password, use the domain-password router configuration command. To disable a password, use the no form of this command.
domain-password password
no domain-password [password]Syntax Description
Default
No password is specified.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This password is inserted in Level 2 (area router level) link state PDUs (LSPs), complete sequence number PDUs (CSNPs), and partial sequence number PDUs (PSNPs).
Example
The following example assigns an authentication password to the routing domain:
router isisdomain-password flowerRelated Command
eigrp log-neighbor-changes
To enable the logging of changes in Enhanced IGRP neighbor adjacencies, use the eigrp log-neighbor-change router configuration command. To disable the logging of changes in Enhanced IGRP neighbor adjacencies, use the no form of this command.
eigrp log-neighbor-changes
no eigrp log-neighbor-changesSyntax Description
This command has not arguments or keywords.
Default
No adjacency changes are logged.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Enables the logging of neighbor adjacency changes to monitor the stability of the routing system and to help detect problems.
Example
The following configuration will log neighbor changes for Enhanced IGRP process 209:
router eigrp 209eigrp log-neighbor-changesip as-path access-list
To define a BGP-related access list, use the ip as-path access-list global configuration command. To disable use of the access list, use the no form of this command.
ip as-path access-list access-list-number {permit | deny} as-regular-expression
no ip as-path access-list access-list-number {permit | deny} as-regular-expressionSyntax Description
Default
No access lists are defined.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in This command first appeared in Cisco IOS Release IOS Release 10.0.
You can specify an access list filter on both inbound and outbound BGP routes. In addition, you can assign weights based on a set of filters. Each filter is an access list based on regular expressions. If the regular expression matches the representation of the autonomous system path of the route as an ASCII string, then the permit or deny condition applies. The autonomous system path does not contain the local autonomous system number. Use the ip as-path access-list global configuration command to define an BGP access list, and the neighbor router configuration command to apply a specific access list.
Example
The following example specifies that the BGP neighbor with IP address 128.125.1.1 is not sent advertisements about any path through or from the adjacent autonomous system 123:
ip as-path access-list 1 deny _123_ip as-path access-list 1 deny ^123$router bgp 109network 131.108.0.0neighbor 129.140.6.6 remote-as 123neighbor 128.125.1.1 remote-as 47neighbor 128.125.1.1 filter-list 1 outRelated Commands
neighbor distribute-list
neighbor filter-listip bandwidth-percent eigrp
To configure the percentage of bandwidth that may be used by enhanced IGRP on an interface, use the ip bandwidth-percent eigrp interface configuration command. To restore the default value, use the no form of this command.
ip bandwidth-percent eigrp as-number percent
no ip bandwidth-percent eigrp as-number percentSyntax Description
Default
50 percent
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Enhanced IGRP will use up to 50 percent of the bandwidth of a link, as defined by the bandwidth interface configuration command. This command may be used if some other fraction of the bandwidth is desired. Note that values greater than 100 percent may be configured; this may be useful if the bandwidth is set artificially low for other reasons.
Example
The following example allows enhanced IGRP to use up to 75 percent (42 kbps) of a 56-kbps serial link in autonomous system 209:interface serial 0bandwidth 56ip bandwidth-percent eigrp 209 75Related Command
A dagger (†) indicates that the command is documented outside this chapter.
bandwidth †
ip cgmp
To enable CGMP on an interface of a router connected to a Catalyst 5000 switch, use the ip cgmp interface configuration command. To disable CGMP routing, use the no form of this command.
ip cgmp [proxy]
no ip cgmpSyntax Description
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
When enabled on an interface, this command triggers a CGMP Join message. This command should only be used on 802 and ATM media. When a no ip cgmp command is issued, a triggered CGMP Leave message is sent for the router's MAC address on the interface for group 0000.0000.0000 (all groups).
When the proxy keyword is specified, the CGMP proxy function is enabled. That is, any router that is not CGMP-capable will be advertised by the proxy router. The proxy router advertises the existence of other non CGMP-capable routers by sending a CGMP Join message with the non CGMP-capable router's MAC address and a group address of 0000.0000.0000.
Examples
In the following example, CGMP is enabled:
ip cgmpIn the following example, CGMP and CGMP proxy are enabled:
ip cgmp proxyip community-list
To create a community list for BGP and control access to it, use the ip community-list global configuration command. To delete the community list, use the no form of this command.
ip community-list community-list-number {permit | deny} community-number
no ip community-list community-list-numberSyntax Description
community-list-number
Integer from 1 to 99 that identifies one or more permit or deny groups of communities.
permit
Permits access for a matching condition.
deny
Denies access for a matching condition.
community-number
Community number configured by a set community command. Valid value is one of the following:
•
•
•
•
Default
Once you permit a value for the community number, the community list defaults to an implicit deny for everything else.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Example
In the following example, the Cisco IOS software permits all routes except the routes with the communities 5 and 10 or 10 and 15:
ip community-list 1 deny 5 10ip community-list 1 deny 10 15ip community-list 1 permit internetRelated Command
ip default-network
To select a network as a candidate route for computing the gateway of last resort, use the ip default-network global configuration command. To remove a route, use the no form of this command.
ip default-network network-number
no ip default-network network-numberSyntax Description
Default
If the router has a directly connected interface onto the specified network, the dynamic routing protocols running on that router will generate (or source) a default route. For RIP, this is flagged as the pseudonetwork 0.0.0.0; for IGRP, it is the network itself, flagged as an exterior route.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The Cisco IOS software uses both administrative distance and metric information to determine the default route. Multiple ip default-network commands can be given. All candidate default routes, both static (that is, flagged by ip default-network) and dynamic, appear in the routing table preceded by an asterisk.
If the IP routing table indicates that the specified network number is subnetted and a non-zero subnet number is specified, then the system will automatically configure a static summary route. This static summary route is configured instead of a default network. The effect of the static summary route is to cause traffic destined for subnets that are not explicitly listed in the IP routing table to be routed using the specified subnet.
Examples
The following example defines a static route to network 10.0.0.0 as the static default route:
ip route 10.0.0.0 255.0.0.0 131.108.3.4ip default-network 10.0.0.0If the following command was issued on a router not connected to network 129.140.0.0, the software might choose the path to that network as a default route when the network appeared in the routing table:
ip default-network 129.140.0.0Related Command
ip dvmrp accept-filter
To configure an acceptance filter for incoming DVMRP reports, use the ip dvmrp accept-filter interface configuration command. To disable this feature, use the no form of this command.
ip dvmrp accept-filter access-list-number [distance] neighbor-list access-list-number
no ip dvmrp accept-filter access-list-number [distance] neighbor-list access-list-numberSyntax Description
Default
All destination reports are accepted with a distance of 0. Default settings accept reports from all neighbors.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The neighbor-list keyword and access-list-number argument first appeared in Cisco IOS 11.2.
Any sources that match the access list are stored in the DVMRP routing table with distance.
The distance is used to compare with the same source in the unicast routing table. The route with the lower distance (either the route in the unicast routing table or that in the DVMRP routing table) takes precedence when computing the Reverse Path Forwarding (RPF) interface for a source of a multicast packet.
By default, the administrative distance for DVMRP routes is 0. This means that they always take precedence over unicast routing table routes. If you have two paths to a source, one through unicast routing (using PIM as the multicast routing protocol) and another path using DVMRP (unicast and multicast routing), and if you want to use the PIM path, use the ip dvmrp accept-filter command to increase the administrative distance for DVMRP routes. For example, if the unicast routing protocol is Enhanced IGRP, which has a default administrative distance of 90, you could define and apply the following access list so the RPF interface used to accept multicast packets will be through the Enhanced IGRP/PIM path:
ip dvmrp accept-filter 1 100access-list 1 permit 0.0.0.0 255.255.255.255Example
The following example applies access list 57 to the interface and sets a distance of 4:
access-list 57 permit 131.108.0.0 0.0.255.255access-list 57 permit 198.92.37.0 0.0.0.255access-list 57 deny 0.0.0.0 255.255.255.255ip dvmrp accept-filter 57 4Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
distance
ip dvmrp metric
show ip dvmrp route
tunnel mode †ip dvmrp auto-summary
To enable DVMRP auto-summarization if it was disabled, use the ip dvmrp auto-summary interface configuration command. To disable the feature, use the no form of this command.
ip dvmrp auto-summary
no ip dvmrp auto-summarySyntax Description
This command has no arguments or keywords.
Default
Enabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
DVMRP auto-summarization occurs when a unicast subnet route is collapsed into a classful network number route. This occurs when the subnet is a different network number than the IP address of the interface (or tunnel) over which the advertisement is sent. If the interface is unnumbered, the network number of the numbered interface the unnumbered interface points to is compared.
You might want to disable this feature if the information you want to send using the ip dvmrp summary-address command is the same as the information that would be sent using DVMRP auto-summarization.
Example
The following example disables DVMRP auto-summarization:
no ip dvmrp auto-summaryRelated Command
ip dvmrp default-information
To advertise network 0.0.0.0 to DVMRP neighbors on an interface, use the ip dvmrp default-information interface configuration command. To prevent the advertisement, use the no form of this command.
ip dvmrp default-information {originate | only}
no ip dvmrp default-information {originate | only}Syntax Description
originate
Other routes more specific than 0.0.0.0 can also be advertised.
only
No DVMRP routes other than 0.0.0.0 are advertised.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
This command should only be used when the router is a neighbor to mrouted version 3.6 machines. The mrouted protocol is a public domain implementation of DVMRP.
You can use the ip dvmrp metric command with the ip dvmrp default-information command to tailor the metric used when advertising the default route 0.0.0.0. By default, metric 1 is used.
Example
The following example configures the Cisco IOS software to advertise network 0.0.0.0, in addition to other networks, to DVMRP neighbors:
ip dvmrp default-information originateRelated Command
ip dvmrp metric
To configure the metric associated with a set of destinations for DVMRP reports, use the ip dvmrp metric interface configuration command. To disable this function, use the no form of this command.
ip dvmrp metric metric [list access-list-number] [[protocol process-id] | dvmrp]
ip dvmrp metric metric route-map map-name
no ip dvmrp metric metric [list access-list-number] [[protocol process-id] | dvmrp]
no ip dvmrp metric metric route-map map-nameSyntax Description
Default
No metric is preconfigured. Only directly connected subnets and networks are advertised to neighboring DVMRP routers.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2. The route-map keyword first appeared in Cisco IOS Release 11.1.
When PIM is configured on an interface and DVMRP neighbors are discovered, the Cisco IOS software sends DVMRP report messages for directly connected networks. The ip dvmrp metric command enables DVMRP report messages for multicast destinations that match the access list. Usually, the metric for these routes is 1. Under certain circumstances, you might want to tailor the metric used for various unicast routes. This command lets you configure the metric associated with a set of destinations for Reports sent out this interface.
You can use the access-list-number argument in conjunction with the protocol process-id arguments to selectively list the destinations learned from a given routing protocol.
To display DVMRP activity, use the debug ip dvmrp command.
Example
The following example connects a PIM cloud to a DVMRP cloud. Access list 1 permits the sending of DVMRP reports to the DVMRP routers advertising all sources in the 198.92.35.0 network with a metric of 1. Access list 2 permits all other destinations, but the metric of 0 means that no DVMRP reports are sent for these destinations.
access-list 1 permit 198.92.35.0 0.0.0.255access-list 1 deny 0.0.0.0 255.255.255.255access-list 2 permit 0.0.0.0 255.255.255.255interface tunnel 0ip dvmrp metric 1 list 1ip dvmrp metric 0 list 2Related Commands
Two daggers (††) indicate that the command is documented in the Debug Command Reference.
debug ip dvmrp ††
ip dvmrp accept-filterip dvmrp metric-offset
To change the metrics of advertised DVMRP routes and thus favor or not favor a certain route, use the ip dvmrp metric-offset interface configuration command. To restore the default values, use the no form of this command.
ip dvmrp metric-offset [in | out] increment
no ip dvmrp metric-offsetSyntax Description
Defaults
If neither in nor out is specified, in is the default.
The default for in is 1.
The default for out is 0.Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Use this command to influence which routes are used, as you prefer. The DVMRP metric is in hop count.
Example
The following example adds 10 to the incoming DVMRP reports:
ip dvmrp metric-offset 10ip dvmrp reject-non-pruners
To configure the router so that it will not peer with a DVMRP neighbor if that neighbor does not support DVMRP pruning or grafting, use the ip dvmrp reject-non-pruners interface configuration command. To disable the feature, use the no form of this command.
ip dvmrp reject-non-pruners
no ip dvmrp reject-non-prunersSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
By default, the router accepts all DVMRP neighbors as peers, regardless of their DVMRP capability or lack thereof.
Use this command to prevent a router from peering with a DVMRP neighbor if that neighbor does not support DVMRP pruning or grafting. If the router receives a DVMRP Probe or Report message without the Prune-Capable flag set, the router logs a syslog message and discards the message.
Note that this command prevents peering with neighbors only. If there are any non-pruning routers multiple hops away (downstream toward potential receivers) that are not rejected, then a non-pruning DVMRP network might still exist.
Example
The following example configures the router not to peer with DVMRP neighbors that do not support pruning or grafting:
ip dvmrp reject-non-prunersip dvmrp routehog-notification
To change the number of DVMRP routes allowed before a syslog warning message is issued, use the ip dvmrp routehog-notification global configuration command. To restore the default value, use the no form of this command.
ip dvmrp routehog-notification route-count
no ip dvmrp routehog-notificationSyntax Description
Default
10,000 routes
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2.
This command configures how many DVMRP routes are accepted on each interface within an approximate one-minute interval before a syslog message is issued, warning that there might be a route surge occurring. The warning is typically used to detect quickly when people have misconfigured their routers to inject a large number of routes into the MBONE.
The show ip igmp interface command displays a running count of routes. When the count is exceeded, an "*** ALERT ***" is appended to the line.
Example
The following example lowers the threshold to 8000 routes:
ip dvmrp routehog-notification 8000Related Command
show ip igmp interface
ip dvmrp route-limit
To change the limit on the number of DVMRP routes that can be advertised over an interface enabled to run DVMRP, use the ip dvmrp route-limit global configuration command. To configure no limit, use the no form of this command.
ip dvmrp route-limit count
no ip dvmrp route-limitSyntax Description
Default
7000 routes
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Interfaces enabled to run DVMRP include a DVMRP tunnel, an interface where a DVMRP neighbor has been discovered, or an interface configured to run ip dvmrp unicast-routing.
The ip dvmrp route-limit command is automatically generated to the configuration file when at least one interface is enabled for multicast routing. This command is necessary to prevent misconfigured ip dvmrp metric commands from causing massive route injection into the multicast backbone (MBONE).
Example
The following example changes the limit to 5000 DVMRP routes allowed to be advertised:
ip dvmrp route-limit 5000Related Command
ip dvmrp summary-address
To configure a DVMRP summary address to be advertised out the interface, use the ip dvmrp summary-address interface configuration command. To remove the summary address, use the no form of this command.
ip dvmrp summary-address address mask [metric value]
no ip dvmrp summary-address address mask [metric value]Syntax Description
Default
metric value is 1
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
If there is at least a single, more specific route in the unicast routing table that matches the specified address and mask, the summary is advertised. Routes in the DVMRP routing table are not candidates for summarization.
When the metric keyword is specified, the summary is advertised with that metric value.
Multiple summary address can be configured on an interface. When multiple overlapping summary addresses are configured on an interface, the one with the longest mask takes preference.
Example
The following example configures the DVMRP summary address 171.69.0.0 to be advertised out the interface:
ip dvmrp summary-address 171.69.0.0 255.255.0.0 metric 1Related Command
ip dvmrp unicast-routing
To enable DVMRP unicast routing on an interface, use the ip dvmrp unicast-routing interface configuration command. To disable the feature, use the no form of this command.
ip dvmrp unicast-routing
no ip dvmrp unicast-routingSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Enabling DVMRP unicast routing means that routes in DVMRP Report messages are cached by the router in a DVMRP routing table. When PIM is running, these routes may get preference over routes in the unicast routing table. This allows PIM to run on the MBONE topology when it is different from the unicast topology.
DVMRP unicast routing can run on all interfaces, including GRE tunnels. On DVMRP tunnels, it runs by virtue of doing DVMRP multicast routing. This command does not enable DVMRP multicast routing among Cisco routers. However, if there is a DVMRP-capable multicast router, the Cisco router will do PIM/DVMRP multicast routing interaction.
Example
The following example enables DVMRP unicast routing:
ip dvmrp unicast-routingRelated Command
ip gdp
To enable GDP routing on an interface, use the ip gdp interface configuration command. To disable GDP routing, use the no form of this command.
ip gdp [priority number | reporttime seconds | holdtime seconds]
no ip gdpSyntax Description
Defaults
priority: 100
reporttime: 5 seconds for broadcast media; 0 for nonbroadcast media
holdtime: 15 secondsCommand Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
When enabled on an interface, GDP updates report the primary and secondary IP addresses of that interface.
Note
Example
In the following example, GDP is enabled on Ethernet interface 1 with a report time of 10 seconds, and priority and hold time set to their defaults (because none are specified):
ip gdp reporttime 10ip hello-interval eigrp
To configure the hello interval for the Enhanced IGRP routing process designated by an autonomous system number, use the ip hello-interval eigrp interface configuration command. To restore the default value, use the no form of this command.
ip hello-interval eigrp autonomous-system-number seconds
no ip hello-interval eigrp autonomous-system-number secondsSyntax Description
Defaults
For low-speed, NBMA networks: 60 seconds
For all other networks: 5 secondsCommand Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The default of 60 seconds applies only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command. Note that for the purposes of Enhanced IGRP, Frame Relay and SMDS networks may or may not be considered to be NBMA. These networks are considered NBMA if the interface has not been configured to use physical multicasting; otherwise they are considered not to be NBMA.
Example
The following example sets the hello interval for Ethernet interface 0 to 10 seconds:
interface ethernet 0ip hello-interval eigrp 109 10Related Command
ip hold-time eigrp
To configure the hold time for a particular Enhanced IGRP routing process designated by the autonomous system number, use the ip hold-time eigrp interface configuration command. To restore the default value, use the no form of this command.
ip hold-time eigrp autonomous-system-number seconds
no ip hold-time eigrp autonomous-system-number secondsSyntax Description
Defaults
For low-speed, NBMA networks: 180 seconds
For all other networks: 15 secondsCommand Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
On very congested and large networks, the default hold time might not be sufficient time for all routers and access servers to receive hello packets from their neighbors. In this case, you may want to increase the hold time.
We recommend that the hold time be at least three times the hello interval. If a router does not receive a hello packet within the specified hold time, routes through this router are considered unavailable.
Increasing the hold time delays route convergence across the network.
The default of 180 seconds hold time and 60 seconds hello interval apply only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command.
Example
The following example sets the hold time for Ethernet interface 0 to 40 seconds:
interface ethernet 0ip hold-time eigrp 109 40Related Command
ip igmp access-group
To control the multicast groups that hosts on the subnet serviced by an interface can join, use the ip igmp access-group interface configuration command. To disable groups on an interface, use the no form of this command.
ip igmp access-group access-list-number version
no ip igmp access-group access-list-number versionSyntax Description
access-list-number
Number of a standard IP access list. This can be a number from 1 to 99.
version
Changes IGMP version. Default is version 2.
Default
All groups are allowed on an interface.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
In the following example, hosts serviced by Ethernet interface 0 can join the group 225.2.2.2 only:
access-list 1 225.2.2.2 0.0.0.0interface ethernet 0ip igmp access-group 1Related Command
ip igmp join-group
To have the router join a multicast group, use the ip igmp join-group interface configuration command. To cancel membership in a multicast group, use the no form of this command.
ip igmp join-group group-address
no ip igmp join-group group-addressSyntax Description
group-address
Address of the multicast group. This is a multicast IP address in four-part, dotted notation.
Default
No multicast group memberships are predefined.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
IP packets that are addressed to the group address are passed to the IP client process in the Cisco IOS software.
If all the multicast-capable routers and access servers that you administer are members of a multicast group, pinging that group causes all routers to respond. This can be a useful administrative and debugging tool.
Another reason to have a router join a multicast group is when other hosts on the network have a bug in IGRP that prevents them from correctly answering IGMP queries. Having the router join the multicast group causes upstream routers to maintain multicast routing table information for that group and keep the paths for that group active.
Example
In the following example, the router joins multicast group 225.2.2.2:
ip igmp join-group 225.2.2.2Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
ip igmp access-group
ping (privileged) †
ping (user) †ip igmp query-interval
To configure the frequency at which the Cisco IOS software sends IGMP host-query messages, use the ip igmp query-interval interface configuration command. To return to the default frequency, use the no form of this command.
ip igmp query-interval seconds
no ip igmp query-intervalSyntax Description
seconds
Frequency, in seconds, at which to transmit IGMP host-query messages. The can be a number from 0 to 65535. The default is 60 seconds.
Default
60 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Multicast routers send host membership query messages (referred to as host-query messages) to discover which multicast groups have members on the router's attached networks. Hosts respond with IGMP report messages indicating that they wish to receive multicast packets for specific groups (that is, indicating that the host wants to become a member of the group). Host-query messages are addresses to the all-hosts multicast group, which has the address 224.0.0.1, and have an IP TTL value of 1.
The designated router for a LAN is the only router that sends IGMP host-query messages.
•
•
If the router hears no queries for the timeout period, it becomes the querier.
Note
Example
The following example changes the frequency at which the designated router sends IGMP host-query messages to 2 minutes:
interface tunnel 0ip igmp query-interval 120Related Commands
ip pim query-interval
show ip igmp groupsip igmp query-max-response-time
To configure the maximum response time advertised in IGMP queries, use the ip igmp query-max-response-time interface configuration command. To restore the default value, use the no form of this command.
ip igmp query-max-response-time seconds
no ip igmp query-max-response-timeSyntax Description
seconds
Maximum response time, in seconds, advertised in IGMP queries. The default value is 10 seconds.
Default
10 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
This command is valid only when IGMP Version 2 is running.
This command controls how long the responder has to respond to an IGMP Query message before the router deletes the group. Configuring a value less than 10 seconds enables the router to prune groups faster.
Keep in mind that if the hosts do not respond fast enough, they might be pruned when you don't want them to be. Therefore, the hosts must know to respond faster than 10 seconds (or the value you configure).
Example
The following example configures a maximum response time of 8 seconds:
ip igmp query-max-response-time 8Related Commands
ip pim query-interval
show ip igmp groupsip igmp query-timeout
To configure the timeout time before the router takes over as the querier for the interface, after the previous querier has stopped querying, use the ip igmp query-timeout interface configuration command. To restore the default value, use the no form of this command.
ip igmp query-timeout seconds
no ip igmp query-timeoutSyntax Description
seconds
Number of seconds that the router waits after the previous querier has stopped querying and before it takes over as the querier.
Default
2 * the query interval
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1. It requires IGMP Version 2.
By default, the router waits 2 * the query interval specified by the ip igmp query-interval command, after which, if it has heard no queries, it becomes the querier. By default, the ip igmp query-interval defaults to 30 seconds, which means the ip igmp query-timeout defaults to 60 seconds.
Example
The following example configures the router to wait 30 seconds from the time it received the last query before it takes over as the querier for the interface:
ip igmp query-timeout 30Related Command
ip igmp query-interval
ip igmp static-group
To configure the router to be a statically connected member of the specified group on the interface, use the ip igmp static-group interface configuration command. To remove the router as a member of the group, use the no form of this command.
ip igmp static-group group-address
no ip igmp static-group group-addressSyntax Description
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
When this command is configured, packets to the group are fast-switched out this interface, provided that packets were received on the correct RPF interface. This is unlike configuring the ip igmp join-group command, which also causes packets to be passed up to the process level.
If the ip igmp join-group command is configured for the same group address as the ip igmp static-group command, the ip igmp join-group command takes precedence, and the group behaves like a locally joined group.
Example
The following example configures 239.100.100.101 on Ethernet 0:
interface ethernet 0ip igmp static-group 239.100.100.101Related Command
ip igmp join-group
ip igmp version
To configure which version of IGMP the router uses, use the ip igmp version interface configuration command. To restore the default value, use the no form of this command.
ip igmp version {2 | 1}
no ip versionSyntax Description
Default
Version 2
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
All systems on the subnet must support the same version. The router does not automatically detect Version 1 systems and switch to Version 1, as did prior releases of the Cisco IOS software.
You would configure Version 1 if your hosts do not support Version 2.
Some commands require IGMP Version 2, such as the ip igmp query-max-response-time and ip igmp query-timeout commands.
Example
The following example configures the router to use IGMP Version 1:
ip igmp version 1Related Commands
ip igmp query-max-response-time
ip igmp query-timeout
show ip igmp groups
show ip igmp interfaceip irdp
To enable ICMP Router Discovery Protocol (IRDP) processing on an interface, use the ip irdp interface configuration command. To disable IRDP routing, use the no form of this command.
ip irdp [multicast | holdtime seconds | maxadvertinterval seconds | minadvertinterval
seconds | preference number | address address [number]]
no ip irdpSyntax Description
Default
Disabled
When enabled, IRDP uses these defaults:
•
•
•
•
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
If you change maxadvertinterval, the other two values also change, so it is important to change maxadvertinterval first before changing either holdtime or minadvertinterval.
The ip irdp multicast command allows for compatibility with Sun Microsystems Solaris, which requires IRDP packets to be sent out as multicasts. Many implementations cannot receive these multicasts; ensure end-host ability before using this command.
Example
The following example illustrates how to set the various IRDP processes:
! enable irdp on interface Ethernet 0interface ethernet 0 ip irdp ! send IRDP advertisements to the multicast addressip irdp multicast ! increase router preference from 100 to 50ip irdp preference 50 ! set maximum time between advertisements to 400 secsip irdp maxadvertinterval 400 ! set minimum time between advertisements to 100 secsip irdp minadvertinterval 100 ! advertisements are good for 6000 secondsip irdp holdtime 6000 ! proxy-advertise 131.108.14.5 with default router preferenceip irdp address 131.108.14.5 ! proxy-advertise 131.108.14.6 with preference of 50ip irdp address 131.108.14.6 50ip local policy route-map
To identify a route map to use for local policy routing, use the ip local policy route-map global configuration command. To disable local policy routing, use the no form of this command.
ip local policy route-map map-tag
no ip local policy route-map map-tagSyntax Description
map-tag
Name of the route map to use for local policy routing. The name must match a map-tag specified by a route-map command.
Default
Packets that are generated by the router are not policy-routed.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1
Packets that are generated by the router are not normally policy-routed. However, you can use this command to policy-route such packets. You might enable local policy routing if you want packets originated at the router to take a route other than the obvious shortest path.
The ip local policy route-map command identifies a route map to use for local policy routing. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which packets should be policy-routed. The set commands specify the set actions—the particular policy routing actions to perform if the criteria enforced by the match commands are met. The no ip local policy route-map command deletes the reference to the route map and disables local policy routing.
Example
In the following example, packets with a destination IP address matching that allowed by extended access list 131 are sent to the router at IP address 174.21.3.20:
ip local policy route-map xxx!route-map xxxmatch ip address 131set ip next-hop 174.21.3.20Related Commands
match ip address
match length
route-map
set default interface
set interface
set ip default next-hop
set ip next-hop
show ip local policyip mroute
To configure a multicast static route (mroute), use the ip mroute global configuration command. To remove the route, use the no form of this command.
ip mroute source mask [protocol as-number] {rpf-address | interface} [distance]
no ip mroute source mask [protocol as-number] {rpf-address | interface} [distance]Syntax Description
Default
distance: 0
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
This command allows you to statically configure where multicast sources are located (even though the unicast routing table says something different).
When a source range is specified, the rpf-address applies only to those sources.
Examples
The following example configures all sources via a single interface (in this case, a tunnel):
ip mroute 0.0.0.0 255.255.255.255 tunnel0The following example configures all specific sources within a network number are reachable through 171.68.10.13:
ip mroute 171.69.0.0 255.255.0.0 171.68.10.13The following example causes this multicast static route to take effect if the unicast routes for any given destination go away:
ip mroute 0.0.0.0 255.255.255.255 serial0 200ip mroute-cache
To configure IP multicast fast switching, use the ip mroute-cache interface configuration command. To disable IP multicast fast switching, use the no form of this command.
ip mroute-cache
no ip mroute-cacheSyntax Description
This command has no arguments or keywords.
Default
Enabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
If fast switching is disabled on an incoming interface for a multicast routing table entry, the packet will be sent at process level for all interfaces in the outgoing interface list.
If fast switching is disabled on an outgoing interface for a multicast routing table entry, the packet is process level switched for that interface, but might be fast-switched for other interfaces in the outgoing interface list.
When fast switching is enabled (like unicast routing), debug messages are not logged. If you want to log debug messages, disable fast switching.
Example
The following example disables IP multicast fast switching on the interface:
no ip mroute-cacheip multicast boundary
To configure an administratively scoped boundary, use the ip multicast boundary interface configuration command. To remove the boundary, use the no form of this command.
ip multicast boundary access-list-number
no ip multicast boundarySyntax Description
access-list-number
Standard IP access list number identifying an access list that controls the range of group addresses affected by the boundary.
Default
There is no boundary.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
You might set up a boundary to keep multicast packets from being forwarded.
Example
The following example sets up a boundary for all administratively scoped addresses:
access-list 1 deny 239.0.0.0 0.255.255.255access-list 1 permit 224.0.0.0 15.255.255.255interface ethernet 0ip multicast boundary 1Related Command
access-list (standard)
ip multicast cache-headers
To allocate a circular buffer to store IP multicast packet headers that the router receives, use the ip multicast cache-headers global configuration command. To disable the feature, use the no form of this command.
ip multicast cache-headers
no ip multicast cache-headersSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
You can store IP multicast packet headers in a cache and then display them to find out:
•
•
•
•
•
•
•
Note
Use the show ip mpacket command to display the buffer.
Example
The following example allocates a buffer to store IP multicast packet headers:
ip multicast cache-headers
Related Command
show ip mpacket
ip multicast helper-map
To allow IP multicast routing in a multicast-capable internetwork between two broadcast-only internetworks, use the ip multicast helper-map interface configuration command. To prevent this feature, use the no form of this command.
ip multicast helper-map {group-address | broadcast} {broadcast-address |
multicast-address} extended-access-list-number
no multicast helper-map {group-address | broadcast} {broadcast-address |
multicast-address} extended-access-list-numberSyntax Description
Default
No conversion between broadcast and multicast occurs.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
When a multicast-capable internetwork is between two broadcast-only internetworks, you can convert broadcast traffic to multicast at the first hop router, and convert it back to broadcast at the last hop router before delivering the packets to the broadcast clients. Thus, you can take advantage of the multicast capability of the intermediate multicast internetwork. This feature prevents unnecessary replication at the intermediate routers and allows multicast fast switching in the multicast internetwork.
Example
The following example illustrates how a helper address on two routers converts from broadcast to multicast and back to broadcast.
The configuration on the first hop router converts a broadcast stream arriving at incoming interface Ethernet 0 destined to UDP port 4000 to a multicast stream. The access list denies other traffic from being forwarded into the multicast cloud. The traffic is sent to group address 224.5.5.5. Because fast switching does not perform such a conversion, the ip forward-protocol command causes the proper process level to perform the conversion.
The configuration on the last hop router converts the multicast stream at incoming interface Ethernet 1 back to broadcast. Again, all multicast traffic emerging from the multicast cloud is not supposed to be converted to broadcast, only the traffic destined for UDP port 4000.
First Hop Router
interface ethernet 0ip multicast helper-map broadcast 224.5.5.5 120ip pim dense-mode!access-list 120 permit any any udp 4000access-list 120 deny any any udpip forward-protocol udp 4000Last Hop Router
interface ethernet 1ip multicast helper-map 224.5.5.5 178.21.34.255 135ip pim dense-mode!access-list 135 permit any any udp 4000access-list 135 deny any any udpip forward-protocol udp 4000Related Command
ip forward-protocol
ip multicast rate-limit
To control the rate a sender from the source-list can send to a multicast group in the group-list, use the ip multicast rate-limit interface configuration command. To remove the control, use the no form of this command.
ip multicast rate-limit {in | out} [video | whiteboard] [group-list access-list] [source-list
access-list] kbps
no multicast rate-limit {in | out} [video | whiteboard] [group-list access-list] [source-list
access-list] kbpsSyntax Description
Default
If this command is not configured, there is no rate limit.
If this command is configured, kbps defaults to 0, meaning that no traffic is permitted.Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
If a router receives a packet and in the last second the user has sent over the limit, the packet is dropped; otherwise, it is forwarded.
For video or whiteboard to work, the ip sdr listen command must be enabled so the port number can be obtained from the sdr cache. If ip sdr listen is not enabled, or the group address is not in the sdr cache, no rate-limiting is done for the group.
Example
In the following example, packets to any group from sources in network 171.69.0.0 will have their packets rate-limited to 64 kbps:
interface serial 0ip multicast rate-limit out group-list 1 source-list 2 64access-list 1 permit 0.0.0.0 255.255.255.255access-list 2 permit 171.69.0.0 0.0.255.255Related Command
ip sdr listen
ip multicast-routing
To enable IP multicast routing, use the ip multicast-routing global configuration command. To disable IP multicast routing, use the no form of this command.
ip multicast-routing
no ip multicast-routingSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
When IP multicast routing is disabled, the Cisco IOS software does not forward any multicast packets.
Example
The following example enables IP multicast routing:
ip multicast-routingRelated Command
ip multicast ttl-threshold
To configure the time-to-live (TTL) threshold of packets being forwarded out an interface, use the ip multicast ttl-threshold interface configuration command. To return to the default TTL threshold, use the no form of this command.
ip multicast ttl-threshold ttl-value
no ip multicast ttl-threshold [ttl-value]Syntax Description
ttl-value
Time-to-live value, in hops. It can be a value from 0 to 255. The default value is 0, which means that all multicast packets are forwarded out the interface.
Default
0, which means that all multicast packets are forwarded out the interface.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Only multicast packets with a TTL value greater than the threshold are forwarded out the interface.
You should configure the TTL threshold only on border routers. Conversely, routers on which you configure a TTL threshold value automatically become border routers.
This command replaces the ip multicast-threshold command, which is obsolete.
Example
In the following example, you set the TTL threshold on a border router to 200, which is a very high value. This means that multicast packets must have a TTL greater than 200 in order to be forwarded out this interface. Multicast applications generally set this value well below 200. Therefore, setting a value of 200 means that no packets will be forwarded out the interface.
interface tunnel 0ip multicast ttl-threshold 200ip ospf authentication-key
To assign a password to be used by neighboring routers that are using OSPF's simple password authentication, use the ip ospf authentication-key interface configuration command. To remove a previously assigned OSPF password, use the no form of this command.
ip ospf authentication-key password
no ip ospf authentication-keySyntax Description
password
Any continuous string of characters that can be entered from the keyboard up to 8 bytes in length.
Default
No password is specified.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The password created by this command is used as a "key" that is inserted directly into the OSPF header when the Cisco IOS software originates routing protocol packets. A separate password can be assigned to each network on a per-interface basis. All neighboring routers on the same network must have the same password to be able to exchange OSPF information.
Note
Example
In the following example, the authentication key is enabled with the string yourpass:
ip ospf authentication-key yourpassRelated Command
ip ospf cost
To explicitly specify the cost of sending a packet on an interface, use the ip ospf cost interface configuration command. To reset the path cost to the default value, use the no form of this command.
ip ospf cost cost
no ip ospf costSyntax Description
cost
Unsigned integer value expressed as the link state metric. It can be a value in the range 1 to 65535.
Default
No default cost is predefined.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can set the metric manually using this command, if you need to change the default. Using the bandwidth command changes the link cost as long as this command is not used.
The link state metric is advertised as the link cost in the router link advertisement. We do not support type of service (TOS), so you can assign only one cost per interface.
In general, the path cost is calculated using the following formula:
108 ÷ Bandwidth
Using this formula, the default path costs were calculated as noted in the following list. If these values do not suit your network, you can use your own method of calculating path costs.
•
•
•
•
•
•
•
•
Example
The following example sets the interface cost value to 65:
ip ospf cost 65ip ospf dead-interval
To set how long hello packets must not have been seen before its neighbors declare the router down, use the ip ospf dead-interval interface configuration command. To return to the default time, use the no form of this command.
ip ospf dead-interval seconds
no ip ospf dead-intervalSyntax Description
seconds
Unsigned integer that specifies the interval in seconds; the value must be the same for all nodes on the network.
Default
Four times the interval set by the ip ospf hello-interval command
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The interval is advertised in the router's hello packets. This value must be the same for all routers and access servers on a specific network.
Example
The following example sets the OSPF dead interval to 60 seconds:
interface ethernet 1 ip ospf dead-interval 60Related Command
ip ospf demand-circuit
To configure OSPF to treat the interface as an OSPF demand circuit, use the ip ospf demand-circuit interface configuration command. To remove the demand circuit designation from the interface, use the no form of this command.
ip ospf demand-circuit
no ip ospf demand-circuitSyntax Description
This command has no arguments or keywords.
Default
The circuit is not a demand circuit.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
On point-to-point interfaces, only one end of the demand circuit must be configured with this command. Periodic hellos are suppressed and periodic refreshes of LSAs do not flood the demand circuit. It allows the underlying datalink layer to be closed when the topology is stable. In point-to-multipoint topology, only the multipoint end must configured with this command.
Example
The following example sets the configures an ISDN on demand circuit:
router ospf1network 18.0.3.0.0.0.0.25 area 0interface BRIOip ospf demand-circuitip ospf hello-interval
To specify the interval between hello packets that the Cisco IOS software sends on the interface, use the ip ospf hello-interval interface configuration command. To return to the default time, use the no form of this command.
ip ospf hello-interval seconds
no ip ospf hello-intervalSyntax Description
seconds
Unsigned integer that specifies the interval in seconds. The value must be the same for all nodes on a specific network.
Default
10 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This value is advertised in the hello packets. The smaller the hello interval, the faster topological changes will be detected, but more routing traffic will ensue. This value must be the same for all routers and access servers on a specific network.
Example
The following example sets the interval between hello packets to 15 seconds:
interface ethernet 1ip ospf hello-interval 15Related Command
ip ospf message-digest-key
To enable OSPF MD5 authentication, use the ip ospf message-digest-key interface configuration command. To remove an old MD5 key, use the no form of this command.
ip ospf message-digest-key keyid md5 key
no ip ospf message-digest-key keyidSyntax Description
Default
OSPF MD5 authentication is disabled.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Usually, one key per interface is used to generate authentication information when sending packets and to authenticate incoming packets. The same key identifier on the neighbor router must have the same key value.
The process of changing keys is as follows. Suppose the current configuration is as follows:
interface ethernet 1ip ospf message-digest-key 100 md5 OLDYou change the configuration to the following:
interface ethernet 1ip ospf message-digest-key 101 md5 NEWThe system assumes its neighbors do not have the new key yet, so it begins a rollover process. It sends multiple copies of the same packet, each authenticated by different keys. In this example, the system sends out two copies of the same packet—the first one authenticated by key 100 and the second one authenticated by key 101.
Rollover allows neighboring routers to continue communication while the network administrator is updating them with the new key. Rollover stops once the local system finds that all its neighbors know the new key. The system detects that a neighbor has the new key when it receives packets from the neighbor authenticated by the new key.
After all neighbors have been updated with the new key, the old key should be removed. In this example, you would enter the following:
interface ethernet 1no ip ospf message-digest-key 100Then, only key 101 is used for authentication on Ethernet interface 1.
We recommend that you not keep more than one key per interface. Every time you add a new key, you should remove the old key to prevent the local system from continuing to communicate with a hostile system that knows the old key. Removing the old key also reduces overhead during rollover.
Example
The following example sets a new key 19 with the password 8ry4222:
interface ethernet 1ip ospf message-digest-key 10 md5 xvv560qleip ospf message-digest-key 19 md5 8ry4222Related Command
area authentication
ip ospf name-lookup
To configure OSPF to look up Domain Name System (DNS) names for use in all OSPF show EXEC command displays, use the ip ospf name-lookup global configuration command. To disable this feature, use the no form of this command.
ip ospf name-lookup
no ip ospf name-lookupSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This feature makes it easier to identify a router because it is displayed by name rather than by its router ID or neighbor ID.
Example
The following example configures OSPF to look up DNS names for use in all OSPF show EXEC command displays:
ip ospf name-lookupSample Display
The following is sample output from the show ip ospf database EXEC command, for example, once you have enabled the DNS name lookup feature:
Router# show ip ospf databaseOSPF Router with id (160.89.41.1) (Autonomous system 109)Router Link States (Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum Link count160.89.41.1 router 381 0x80000003 0x93BB 4160.89.34.2 neon 380 0x80000003 0xD5C8 2Net Link States (Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum160.89.32.1 router 381 0x80000001 0xC117ip ospf network
To configure the OSPF network type to a type other than the default for a given media, use the ip ospf network interface configuration command. To return to the default value, use the no form of this command.
ip ospf network {broadcast | non-broadcast | point-to-multipoint}
no ip ospf networkSyntax Description
broadcast
Sets the network type to broadcast.
non-broadcast
Sets the network type to nonbroadcast.
point-to-multipoint
Sets the network type to point-to-multipoint.
Default
Depends on the network type.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The point-to-multipoint keyword first appeared in Cisco IOS Release 10.3.
Using this feature, you can configure broadcast networks as nonbroadcast multiaccess (NBMA) networks when, for example, you have routers in your network that do not support multicast addressing. You can also configure nonbroadcast multiaccess networks (such as X.25, Frame Relay, and SMDS) as broadcast networks. This feature saves you from having to configure neighbors.
Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every router or fully meshed network. This is not true for some cases, for example, because of cost constraints or when you have only a partially meshed network. In these cases, you can configure the OSPF network type as a point-to-multipoint network. Routing between two routers that are not directly connected will go through the router that has virtual circuits to both routers. Note that you do not need to configure neighbors when using this feature.
If this command is issued on an interface that does not allow it, it will be ignored.
Example
The following example sets your OSPF network as a broadcast network:
interface serial 0 ip address 160.89.77.17 255.255.255.0ip ospf network broadcastencapsulation frame-relayRelated Commands
A dagger (†) indicates that the command is documented outside this chapter.
frame-relay map †
neighbor (OSPF)
x25 map †ip ospf priority
To set the router priority, which helps determine the designated router for this network, use the ip ospf priority interface configuration command. To return to the default value, use the no form of this command.
ip ospf priority number
no ip ospf prioritySyntax Description
Default
Priority of 1
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
When two routers attached to a network both attempt to become the designated router, the one with the higher router priority takes precedence. If there is a tie, the router with the higher router ID takes precedence. A router with a router priority set to zero is ineligible to become the designated router or backup designated router. Router priority is only configured for interfaces to multiaccess networks (in other words, not point-to-point networks).
This priority value is used when you configure OSPF for nonbroadcast networks using the neighbor router configuration command for OSPF.
Example
The following example sets the router priority value to 4:
interface ethernet 0 ip ospf priority 4Related Commands
ip ospf network
neighbor (OSPF)ip ospf retransmit-interval
To specify the time between link state advertisement retransmissions for adjacencies belonging to the interface, use the ip ospf retransmit-interval interface configuration command. To return to the default value, use the no form of this command.
ip ospf retransmit-interval seconds
no ip ospf retransmit-intervalSyntax Description
Default
5 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
When a router sends a link state advertisement (LSA) to its neighbor, it keeps the LSA until it receives back the acknowledgment. If it receives no acknowledgment in seconds, it will retransmit the LSA.
The setting of this parameter should be conservative, or needless retransmission will result. The value should be larger for serial lines and virtual links.
Example
The following example sets the retransmit-interval value to 8 seconds:
interface ethernet 2 ip ospf retransmit-interval 8ip ospf transmit-delay
To set the estimated time it takes to transmit a link state update packet on the interface, use the ip ospf transmit-delay interface configuration command. To return to the default value, use the no form of this command.
ip ospf transmit-delay seconds
no ip ospf transmit-delaySyntax Description
seconds
Time in seconds that it takes to transmit a link state update. It can be an integer in the range is 1 to 65535 seconds. The default is 1 second.
Default
1 second
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Link state advertisements in the update packet must have their ages incremented by the amount specified in the seconds argument before transmission. The value assigned should take into account the transmission and propagation delays for the interface.
If the delay is not added before transmission over a link, the time in which the LSA propagates over the link is not considered. This setting has more significance on very low speed links.
Example
The following example sets the retransmit-delay value to 3 seconds:
interface ethernet 0 ip ospf transmit-delay 3ip pim
To enable PIM on an interface, use the ip pim interface configuration command. To disable PIM on the interface, use the no form of this command.
ip pim {dense-mode | sparse-mode | sparse-dense-mode}
no ip pimSyntax Description
dense-mode
Enables dense mode of operation.
sparse-mode
Enables sparse mode of operation.
sparse-dense-mode
The interface is treated in the mode in which the group operates.
Default
IP multicast routing is disabled on all interfaces.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The sparse-dense-mode keyword first appeared in Cisco IOS Release 11.1.
Enabling PIM on an interface also enables IGMP operation on that interface. An interface can be configured to be in dense mode, sparse mode, or sparse-dense mode. The mode describes how the Cisco IOS software populates its multicast routing table and how the software forwards multicast packets it receives from its directly connected LANs. In populating the multicast routing table, dense-mode interfaces are always added to the table. Sparse-mode interfaces are added to the table only when periodic join messages are received from downstream routers, or there is a directly connected member on the interface.
Dense Mode
Initially, a dense-mode interface forwards multicast packets until the router determines that there are group members or downstream routers, or until a prune message is received from a downstream router. Then, the dense-mode interface periodically forwards multicast packets out the interface until the same conditions occur. Dense mode assumes that there are multicast group members present. Dense-mode routers never send a join message. They do send prune messages as soon as they determine they have no members or downstream PIM routers. A dense-mode interface is subject to multicast flooding by default.
Sparse Mode
A sparse-mode interface is used for multicast forwarding only if a join message is received from a downstream router or if there are group members directly connected to the interface. Sparse mode assumes that there are no other multicast group members present. When sparse-mode routers want to join the shared path, they periodically send join messages toward the rendezvous point (RP). When sparse-mode routers want to join the source path, they periodically send join messages toward the source; they also send periodic prune messages toward to RP to prune the shared path.
Sparse-Dense Mode
An alternative to choosing just dense mode or just sparse mode is to run PIM in a single region in sparse mode for some groups and dense mode for other groups.
In sparse-dense mode, if the group is in dense mode, the interface will be treated as dense mode. If the group is in sparse mode, the interface will be treated in sparse mode. The group is "sparse" if the router knows about an RP for that group.
When an interface is treated in dense mode, it is populated in a multicast routing table's outgoing integrated list when either
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•
When an interface is treated in sparse mode, it is populated in a multicast routing table's outgoing interface when either
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Examples
The following commands enables sparse-mode PIM on tunnel interface 0 and sets the address of the RP router to 226.0.0.8:
ip pim rp-address 226.0.0.8interface tunnel 0ip pim sparse-modeThe following commands enable dense-mode PIM on Ethernet interface 1:
interface ethernet 1ip pim dense-modeRelated Commands
ip multicast-routing
ip pim rp-address
show ip pim interfaceip pim accept-rp
To configure a router to accept Joins or Prunes destined for a specified RP and for a specific list of groups, use the ip pim accept-rp global configuration command. To remove that check, use the no form of this command.
ip pim accept-rp {address | auto-rp} [group-access-list-number]
no ip pim accept-rp {ip-address | auto-rp} [group-access-list-number]Syntax Description
Default
Disabled, so all Join messages and Prune messages are processed.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2.
This command causes the router to accept only (*,G) Join messages destined for the specified RP address. Additionally, the group address must be in the range specified by the access list.
When address is one of the system's addresses, the system will be the RP only for the specified group range specified by the access list. When the group address is not in the group range, the RP will not accept Join or Register messages and will respond immediately to Registers with Register-Stop messages.
Example
The following example states that the router will accept Join or Prune messages destined for the RP at address 100.1.1.1 for the multicast group 224.2.2.2:
ip pim accept-rp 100.1.1.1 3access-list 3 permit 224.2.2.2Related Command
access-list (standard)
ip pim message-interval
To configure the frequency at which a sparse-mode PIM router sends periodic sparse-mode join/prune PIM messages, use the ip pim message-interval global configuration command. To return to the default interval, use the no form of this command.
ip pim message-interval seconds
no ip pim message-interval [seconds]Syntax Description
seconds
Interval, in seconds, at which periodic sparse-mode join and prune PIM messages are sent. It can be a number from 1 to 65535. The default is 60 seconds.
Default
60 seconds
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
The join-and-prune message interval should be the same for all routers in the internetwork.
A router is pruned from a group if a join message is not heard from it in three times the message interval specified by the seconds argument. By default, this is 3 minutes.
Note
Example
The following example changes the PIM message interval to 90 seconds:
ip pim message-interval 90Related Commands
ip igmp query-interval
ip pim query-intervalip pim nbma-mode
To configure a multiaccess WAN interface to be in nonbroadcast, multiaccess mode, use the ip pim nbma-mode interface configuration command. To disable this feature, use the no form of this command.
ip pim nbma-mode
no ip pim nbma-modeSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Use this command on Frame Relay, SMDS, or ATM only, especially when these media do not have native multicast available. Do not use this command on multicast-capable LANs such as Ethernet or FDDI.
When this command is configured, each PIM Join message is kept track of in the outgoing interface list of a multicast routing table entry. Therefore, only PIM WAN neighbors that have joined for the group will get packets sent as data link unicasts. This command should only be used when ip pim sparse-mode is configured on the interface. This command is not recommended for LANs that have natural multicast capabilities.
Example
The following example configures an interface to be in nonbroadcast, multiaccess mode:
ip pim nbma-modeRelated Command
ip pim sparse-mode
ip pim query-interval
To configure the frequency of PIM router-query messages, use the ip pim query-interval interface configuration command. To return to the default interval, use the no form of this command.
ip pim query-interval seconds
no ip pim query-interval [seconds]Syntax Description
seconds
Interval, in seconds, at which periodic PIM router-query messages are sent. It can be a number from 1 to 65535. The default is 30 seconds.
Default
30 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Routers configured for IP multicast send PIM router-query messages to determine which router will be the designated router for each LAN segment (subnet). The designated router is responsible for sending IGMP host-query messages to all hosts on the directly connected LAN. When operating in sparse mode, the designated router is responsible for sending source registration messages to the RP. The designated router is the router with the largest IP address.
Example
The following example changes the PIM router-query message interval to 45 seconds:
interface tunnel 0ip pim query-interval 45Related Command
ip pim rp-address
To configure the address of a PIM rendezvous point (RP) for a particular group, use the ip pim rp-address global configuration command. To remove an RP address, use the no form of this command.
ip pim rp-address ip-address [group-access-list-number] [override]
no ip pim rp-address ip-address [access-list-number]Syntax Description
Default
No PIM RPs are preconfigured.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2.
You must configure the IP address of RPs in leaf designated routers (DRs) only. Leaf routers are those routers that are directly connected either to a multicast group member or to a sender of multicast messages. Leaf DRs are the only ones that need to know about RPs. Even potential DRs (that might be elected if the primary DR fails) need to be configured to know about RPs.
First-hop routers send register packets to the RP address on behalf of source multicast hosts. Routers also use this address on behalf of multicast hosts that want to become members of a group. These routers send Join and Prune messages towards the RP. The RP must be a PIM router; however, it does not require any special configuration to recognize that it is the RP. Also, RPs are not members of the multicast group; rather, they serve as a "meeting place" for multicast sources and group members.
You can configure the Cisco IOS software to use a single RP for more than one group. The conditions specified by the access list determine which groups the RP can be used for. If no access list is configured, the RP is used for all groups.
A PIM router can use multiple RPs, but only one per group.
If there is no RP configured for a group, the router will treat the group as dense using the dense-mode PIM techniques.
If the RP for a group is learned through a dynamic mechanism, such as Auto-RP, then this command might not be required. If there is a conflict between the RP configured with this command and one learned by Auto-RP, the Auto-RP information is used, unless the override keyword is specified.
Examples
The following example sets the PIM RP address to 198.92.37.33 for all multicast groups:
ip pim rp-address 198.92.37.33The following example sets the PIM RP address to 147.106.6.22 for the multicast group 225.2.2.2 only:
access list 1 225.2.2.2 0.0.0.0ip pim rp-address 147.106.6.22 1Related Command
access-list (standard)
ip pim rp-announce-filter
To filter incoming Auto-RP announcement messages coming from the RP, use the ip pim rp-announce-filter global configuration command. To remove the filter, use the no form of this command.
ip pim rp-announce-filter rp-list access-list-number group-list access-list-number
no ip rp-announce-filter rp-list access-list-number group-list access-list-numberSyntax Description
Default
All RP announcements are accepted.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Configure this command on the PIM RP-mapping agent. If you are going to use more than one RP-mapping agent, make the filters among them consistent so that there are no conflicts in mapping state when the announcing agent goes down.
Example
The following example configures the router to accept RP announcements from RPs in access list 1 for group ranges described in access-list 2:
ip pim rp-announce-filter rp-list 1 group-list 2exitaccess-list 1 permit 10.0.0.1access-list 1 permit 10.0.0.2access-list 2 permit 224.0.0.0 15.255.255.255Related Command
access-list (standard)
ip pim send-rp-announce
To use Auto-RP to configure which groups the router is willing to act as RP for, use the ip pim send-rp-announce global configuration command. To deconfigure this router to be the RP, use the no form of this command.
ip pim send-rp-announce type number scope ttl group-list access-list-number
no ip pim send-rp-announceSyntax Description
Default
Auto-RP is disabled.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Use this command in the router you want to be an RP. This command causes the router to send an Auto-RP announcement message to the well-known group CISCO-RP-ANNOUNCE (224.0.1.39). This message announces the router as a candidate RP for the groups in the range described by the access list.
Example
The following example sends RP announcements out all PIM-enabled interfaces for a maximum of 31 hops. The IP address the router wants to be identified by as RP is the IP address associated with Ethernet interface 0. Access-list 5 describes for which groups this router serves as RP.
ip pim send-rp-announce ethernet0 scope 31 group-list 5access-list 5 permit 224.0.0.0 15.255.255.255Related Command
access-list (standard)
ip pim send-rp-discovery
To configure the router to be an RP-mapping agent, use the ip pim send-rp-discovery global configuration command. To restore the default value, use the no form of this command.
ip pim send-rp-discovery scope ttl
no ip pim send-rp-discoverySyntax Description
scope ttl
Time-to-live value in the IP header that keeps the discovery messages within this number of hops.
Default
The router is not an RP mapping agent.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Configure this command on the router designated as an RP-mapping agent. Specify a TTL large enough to cover your PIM domain.
When Auto-RP is used, the following steps occur:
1
2
3
Example
The following example limits Auto-RP RP Discovery messages to 20 hops:
ip pim send-rp-discovery scope 20ip pim spt-threshold
To configure when a PIM leaf router should join the shortest path source-tree for the specified group, use the ip pim spt-threshold global configuration command. To restore the default value, use the no form of this command.
ip pim spt-threshold {kbps | infinity} [group-list access-list-number]
no ip pim spt-thresholdSyntax Description
Default
When this command is not used, the PIM leaf router joins the shortest path tree immediately after the first packet arrives from a new source.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
If a source sends at a rate greater than or equal to kbps, a PIM Join message is triggered toward the source to construct a source-tree.
If infinity is specified, all sources for the specified group will use the shared-tree. Specifying a group-list access list indicates what groups the threshold applies to.
If the traffic rate from the source drops below the threshold kbps, the leaf router will, after some amount of time, switch back to the shared tree and send a Prune toward the source.
Example
The following example sets a threshold of 4 kbps, above which traffic to a group from a source will cause the router to switch to the shortest path tree to that source:
ip pim spt-threshold 4ip policy route-map
To identify a route map to use for policy routing on an interface, use the ip policy route-map interface configuration command. To disable policy routing on the interface, use the no form of this command.
ip policy route-map map-tag
no ip policy route-map map-tagSyntax Description
map-tag
Name of the route map to use for policy routing. Must match a map-tag specified by a route-map command.
Default
No policy routing occurs on the interface.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
You might enable policy routing if you want your packets to take a route other than the obvious shortest path.
The ip policy route-map command identifies a route map to use for policy routing. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which policy routing is allowed for the interface. The set commands specify the set actions—the particular policy routing actions to perform if the criteria enforced by the match commands are met. The no ip policy route-map command deletes the pointer to the route map.
Example
In the following example, packets with the destination IP address of 174.95.16.18 are sent to a router at IP address 174.21.3.20:
interface serial 0ip policy route-map wethersfield!route-map wethersfieldmatch ip address 174.95.16.18set ip next-hop 174.21.3.20Related Commands
match ip address
match length
route-map
set default interface
set interface
set ip default next-hop
set ip next-hopip rip authentication key-chain
To enable authentication for RIP Version 2 packets and to specify the set of keys that can be used on an interface, use the ip rip authentication key-chain interface configuration command. Use the no form of this command to prevent authentication.
ip rip authentication key-chain name-of-chain
no ip rip authentication key-chain [name-of-chain ]Syntax Description
Default
No authentication is provided for RIP packets.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
If no key chain is configured with the key-chain command, no authentication is performed on the interface (not even the default authentication).
Example
The following example configures the interface to accept and send any key belonging to the key chain named trees:
ip rip authentication key-chain treesRelated Command
ip rip authentication mode
To specify the type of authentication used in RIP Version 2 packets, use the ip rip authentication mode interface configuration command. Use the no form of this command to restore clear text authentication.
ip rip authentication mode {text | md5}
no ip rip authentication modeSyntax Description
Default
Clear text authentication is provided for RIP packets.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
RIP Version 1 does not support authentication.
Example
The following example configures the interface to use MD5 authentication:
ip rip authentication mode md5Related Commands
ip rip authentication key-chain
key chainip rip receive version
To specify a RIP version to receive on an interface basis, use the ip rip receive version interface configuration command. Use the no form of this command to follow the global version rules.
ip rip receive version [1] [2]
no ip rip receive versionSyntax Description
1
(Optional) Accepts only RIP Version 1 packets on the interface.
2
(Optional) Accepts only RIP Version 2 packets on the interface.
Default
The software behaves according to the version command.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Use this command to override the default behavior of RIP as specified by the version command. This command applies only to the interface being configured. You can configure the interface to accept both RIP versions.
Examples
The following example configures the interface to receive both RIP Version 1 and Version 2 packets:
ip rip receive version 1 2The following example configures the interface to receive only RIP Version 1 packets:
ip rip receive version 1Related Commands
ip rip send version
To specify a RIP version to send on an interface basis, use the ip rip send version interface configuration command. Use the no form of this command to follow the global version rules.
ip rip send version [1] [2]
no ip rip send versionSyntax Description
1
(Optional) Sends only RIP Version 1 packets out the interface.
2
(Optional) Sends only RIP Version 2 packets out the interface.
Default
The software behaves according to the router version command.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Use this command to override the default behavior of RIP as specified by the router version command. This command applies only to the interface being configured.
Examples
The following example configures the interface to send both RIP Version 1 and Version 2 packets out the interface:
ip rip send version 1 2The following example configures the interface to send only RIP Version 2 packets out the interface:
ip rip send version 2Related Commands
ip route
To establish static routes, use the ip route global configuration command. To remove static routes, use the no form of this command.
ip route prefix mask {address | interface} [distance] [tag tag] [permanent]
no ip route prefix maskSyntax Description
Default
No static routes are established.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
A static route is appropriate when the Cisco IOS software cannot dynamically build a route to the destination.
If you specify an administrative distance, you are flagging a static route that can be overridden by dynamic information. For example, IGRP-derived routes have a default administrative distance of 100. To have a static route that would be overridden by an IGRP dynamic route, specify an administrative distance greater than 100. Static routes have a default administrative distance of 1.
Static routes that point to an interface will be advertised via RIP, IGRP, and other dynamic routing protocols, regardless of whether redistribute static commands were specified for those routing protocols. This is because static routes that point to an interface are considered in the routing table to be connected and hence lose their static nature. However, if you define a static route to an interface that is not one of the networks defined in a network command, no dynamic routing protocols will advertise the route unless a redistribute static command is specified for these protocols.
Examples
In the following example, an administrative distance of 110 was chosen. In this case, packets for network 10.0.0.0 will be routed through to a router at 131.108.3.4 if dynamic information with administrative distance less than 110 is not available.
ip route 10.0.0.0 255.0.0.0 131.108.3.4 110In the following example, packets for network 131.108.0.0 will be routed to a router at 131.108.6.6:
ip route 131.108.0.0 255.255.0.0 131.108.6.6ip router isis
To configure an IS-IS routing process for IP on an interface, use the ip router isis interface configuration command. To disable IS-IS for IP, use the no form of this command.
ip router isis [tag]
no ip router isis [tag]Syntax Description
Default
No routing processes are specified.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
The following example specifies IS-IS as an IP routing protocol for a process named Finance, and specifies that the Finance process will be routed on interfaces Ethernet 0 and serial 0:
router isis Financeinterface Ethernet 0ip router isis Financeinterface serial 0ip router isis FinanceRelated Command
ip rsvp bandwidth
To enable the use of the Resource Reservation Protocol (RSVP) protocol for IP on an interface, use the ip rsvp bandwidth interface configuration command. To disable this feature, use the no form of the command.
ip rsvp bandwidth [interface-kbps] [single-flow-kbps]
no ip rsvp bandwidth [interface-kbps] [single-flow-kbps]Syntax Description
interface-kbps
(Optional) Amount of bandwidth on interface to be reserved.
single-flow-kbps
(Optional) Amount of bandwidth allocated to single flow.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Use this command to enable the use of the RSVP for IP on an interface. The default is for RSVP to be disabled to allow backward compatibility with systems that do not implement RSVP.
Example
The following example shows a T1 (1536 kbps) link configured to permit RSVP reservation of up to 1158 kbps, but no more than 100 kbps for any given flow on interfaces Ethernet 0 and serial 0. Fair queuing is configured with 15 reservable queues to support those reserved flows should they be required.
interface Ethernet 0ip rsvp bandwidth 1158 100interface serial 0fair-queue 64 256 15Related Commands
ip rsvp neighbors
ip rsvp reservation
ip rsvp sender
ip rsvp udp-multicastip rsvp neighbors
To enable neighbors to offer a reservation, use the ip rsvp neighbors interface configuration command. To disable this feature, use the no form of the command.
ip rsvp neighbors access-list-number
no ip rsvp neighbors access-list-numberSyntax Description
access-list-number
Number of a standard or extended access list. It can be an integer from 1 to 199.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in IOS Release 11.2.
Use this command to allow RSVP neighbors to make a reservation. If no limits are specified, any neighbor can offer a reservation. If an access list is specified, only neighbors meeting the specified access list requirements can make a reservation.
Related Commands
ip rsvp bandwidth
ip rsvp udp-multicast
ip rsvp sender
ip rsvp reservationip rsvp reservation
To enable a router to simulate Resource Reservation Protocol RSVP) RESV message reception from the sender, use the ip rsvp reservation interface configuration command. To disable this feature, use the no form of the command.
ip rsvp reservation session-ip-address sender-ip-address [tcp | udp | ip-protocol]
session-dport sender-sport next-hop-ip address nexthop-interface {ff | se | wf} {rate | load}
[bandwidth] [burst-size]no ip rsvp reservation session-ip-address sender-ip-address [tcp | udp | ip-protocol]
session-dport sender-sport next-hop-ip address nexthop-interface {ff | se | wf} {rate | load}
[bandwidth] [burst-size]Syntax Description
Default
The router cannot simulate receiving an RSVP RESV Message.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Use this command to force the router to act like it is receiving RSVP RESV messages from the sender.
Examples
The following example specifies the use of a Shared Explicit Filter style of reservation and the Controlled Load Service, and with token buckets of 100 or 150 kbps and 60 or 65K maximum queue depth:
ip rsvp reservation 224.250.0.2 132.240.1.1 UDP 20 30 132.240.4.1 Et1 se load 100 60ip rsvp reservation 224.250.0.2 132.240.2.1 TCP 20 30 132.240.4.1 Et1 se load 150 65The following example specifies the use of a Wild Card Filter style of reservation and the Guaranteed Bit Rate Service, and with token buckets of 300 or 350 kbps and 60 or 65K maximum queue depth:
ip rsvp reservation 224.250.0.3 0.0.0.0 UDP 20 0 132.240.4.1 Et1 wf rate 300 60ip rsvp reservation 224.250.0.3 0.0.0.0 UDP 20 0 132.240.4.1 Et1 wf rate 350 65Note that the Wild Card Filter does not admit the specification of the sender; it accepts all senders. This is denoted by setting the source address and port to zero. If, in any filter style, the destination port is specified to be zero, RSVP does not permit the source port to be anything else; it understands that such protocols do not use ports or that the specification applies to all ports.
Related Commands
ip rsvp bandwidth
ip rsvp neighbors
ip rsvp sender
ip rsvp udp-multicastip rsvp sender
To enable a router to simulate Resource Reservation Protocol RSVP) PATH message reception from the sender, use the ip rsvp sender interface configuration command. To disable this feature, use the no form of the command.
ip rsvp sender session-ip-address sender-ip-address [tcp | udp | ip-protocol] session-dport
sender-sport previous-hop-ip-address previous-hop-interface [bandwidth] [burst-size]no ip rsvp sender session-ip-address sender-ip-address [tcp | udp | ip-protocol] session-dport
sender-sport previous-hop-ip-address previous-hop-interface [bandwidth] [burst-size]Syntax Description
Default
The router cannot simulate RSVP Path message reception.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Use this command to force the router to act like it is receiving RSVP PATH messages from the sender.
Example
The following example sets up the router to act like it receiving RSVP messages using UDP over the Eth1 serial interface.
ip rsvp sender 224.250.0.1 132.240.2.1 UDP 20 30 132.240.2.1 Lo1 50 5ip rsvp sender 224.250.0.2 132.240.2.1 UDP 20 30 132.240.2.1 Lo1 50 5ip rsvp sender 224.250.0.2 132.240.2.28 UDP 20 30 132.240.2.28 Lo1 50 5Related Commands
ip rsvp bandwidth
ip rsvp neighbors
ip rsvp reservation
ip rsvp udp-multicastip rsvp udp-multicast
To instruct the router to generate UDP-encapsulated Resource Reservation Protocol (RSVP) multicasts whenever it generates an IP multicast, use the ip rsvp udp-multicast interface configuration command. To disable this feature, use the no form of the command.
ip rsvp udp-multicast [multicast-address]
no ip rsvp udp-multicast [multicast-address]Syntax Description
Default
The generation of UDP multicasts is not enabled. If a system sends a UDP-encapsulated RSVP message to the router, the router starts using UDP for contact with the neighboring system. The router uses multicast address 224.0.0.14 and starts sending to UDP port 1699. If the command is entered without specifying a multicast address, the router uses the same multicast address.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Use this command to instruct a router to generate UDP-encapsulated RSVP multicasts whenever it generates an IP-encapsulated multicast packet. Some hosts require this trigger from the router.
Example
The following example reserves up to 7500 kbps on the Ethernet 2, with up to 1 Mbps per flow. The router is configured to use UDP encapsulation with the multicast address 224.0.0.14.
interface Ethernet 2ip rsvp bandwidth 7500 1000ip rsvp udp-multicast 224.0.0.14Related Commands
ip rsvp bandwidth
ip rsvp neighbors
ip rsvp sender
ip rsvp reservationip sdr cache-timeout
To limit how long an sdr cache entry stays active in the cache, use the ip sdr cache-timeout global configuration command. To restore the default value, use the no form of this command.
ip sdr cache-timeout minutes
no ip sdr cache-timeoutSyntax Description
Default
Disabled, which means entries are never deleted from the cache.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Example
The following example causes sdr cache entries to remain in the cache for only 30 minutes:
ip sdr cache-timeout 30Related Commands
ip sdr listen
To enable the Cisco IOS software to listen to session directory advertisements, use the ip sdr listen interface configuration command. To disable the feature, use the no form of this command.
ip sdr listen
no ip sdr listenSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1. This command replaces the ip sd listen command, which is obsolete.
Session Directory Protocol (sdr) is a multicast application for setting up desktop conferencing sessions. It allocates group addresses and allows the user to specify the scope of the group and whether audio, video, or whiteboard applications will be invoked when users open the session.
Use this command to store session advertisements sent to the group. The ip sdr listen command merely enables the software to listen to session directory advertisements. The router joins the default session directory group (group 224.2.127.254) on the interface. Use this command to get contact information.
Example
The following example enables a router to listen to session directory advertisements:
ip sdr listenRelated Commands
ip split-horizon
To enable the split horizon mechanism, use the ip split-horizon interface configuration command. To disable the split horizon mechanism, use the no form of this command.
ip split-horizon
no ip split-horizonSyntax Description
This command has no arguments or keywords.
Default
Varies with media
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
For all interfaces except those for which either Frame Relay or SMDS encapsulation is enabled, the default condition for this command is ip split-horizon; in other words, the split horizon feature is active. If the interface configuration includes either the encapsulation frame-relay or encapsulation smds commands, then the default is for split horizon to be disabled. Split horizon is not disabled by default for interfaces using any of the X.25 encapsulations.
Note
If split horizon has been disabled on an interface and you wish to enable it, use the ip split-horizon command to restore the split horizon mechanism.
Note
Example
The following simple example disables split horizon on a serial link. The serial link is connected to an X.25 network:
interface serial 0encapsulation x25no ip split-horizonRelated Commands
ip split-horizon eigrp
neighborip split-horizon eigrp
To enable Enhanced IGRP split horizon, use the ip split-horizon eigrp interface configuration command. To disable split horizon, use the no form of this command.
ip split-horizon eigrp autonomous-system-number
no ip split-horizon eigrp autonomous-system-numberSyntax Description
Default
Enabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
For networks that include links over X.25 PSNs, you can use the neighbor router configuration command to defeat the split horizon feature. As an alternative, you can explicitly specify the no ip split-horizon eigrp command in your configuration. However, if you do so, you must similarly disable split horizon for all routers and access servers in any relevant multicast groups on that network.
In general, it is recommended that you not change the default state of split horizon unless you are certain that your application requires the change in order to properly advertise routes. Remember that if split horizon is disabled on a serial interface and that interface is attached to a packet-switched network, you must disable split horizon for all routers and access servers in any relevant multicast groups on that network.
Example
The following example disables split horizon on a serial link connected to an X.25 network:
interface serial 0encapsulation x25no ip split-horizon eigrpRelated Commands
ip split-horizon
neighbor (EGP, EIGRP, IGRP, RIP)ip summary-address eigrp
To configure a summary aggregate address for a specified interface, use the ip summary-address eigrp interface configuration command. To disable a configuration, use the no form of this command.
ip summary-address eigrp autonomous-system-number address mask
no ip summary-address eigrp autonomous-system-number address maskSyntax Description
autonomous-system-number
Autonomous system number.
address
IP summary aggregate address to apply to an interface.
mask
Subnet mask.
Default
No summary aggregate addresses are predefined.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Enhanced IGRP summary routes are given an administrative distance value of 5. You cannot configure this value.
Example
The following example sets the IP summary aggregate address for Ethernet interface 0:
interface ethernet 0ip summary-address eigrp 109 192.1.0.0 255.255.0.0Related Command
isis circuit-type
To configure the type of adjacency, use the isis circuit-type interface configuration command. To reset the circuit type to Level l and Level 2, use the no form of this command.
isis circuit-type {level-1 | level-1-2 | level-2-only}
no isis circuit-typeSyntax Description
Default
A Level 1 and Level 2 adjacency is established.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
In the following example, a router is configured to require Level 1 adjacency if there is at least one area address in common between this system and its neighbors:
ip router isisinterface serial 0isis circuit-type level-1isis csnp-interval
To configure the IS-IS complete sequence number PDUs (CSNP) interval, use the isis csnp-interval interface configuration command. To restore the default value, use the no form of this command.
isis csnp-interval seconds {level-1 | level-2}
no isis csnp-interval {level-1 | level-2}Syntax Description
Default
10 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This command only applies for the designated router (DR) for a specified interface. Only DRs send CSNP packets in order to maintain database synchronization. The CSNP interval can be configured independently for Level 1 and Level 2. This feature does not apply to serial point-to-point interfaces. It does apply to WAN connections if the WAN is viewed as a multiaccess meshed network.
Example
In the following example, serial interface 0 is configured for transmitting CSN PDUs every 5 seconds. The router is configured to act as a station router.
interface serial 0isis csnp-interval 5 level-1isis hello-interval
To specify the length of time between hello packets that the Cisco IOS software sends, use the isis hello-interval interface configuration command. To restore the default value, use the no form of this command.
isis hello-interval seconds {level-1 | level-2}
no isis hello-interval {level-1 | level-2}Syntax Description
Default
10 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The hello interval can be configured independently for Level 1 and Level 2, except on serial point-to-point interfaces. (Because there is only a single type of hello packet sent on serial links, it is independent of Level 1 or Level 2.) The level-1 and level-2 keywords are used on X.25, SMDS, and Frame Relay multiaccess networks.
Example
In the following example, serial interface 0 is configured to advertise hello packets every 5 seconds. The router is configured to act as a station router. This will cause more traffic than configuring a longer interval, but topological changes will be detected faster.
interface serial 0isis hello-interval 5 level-1isis metric
To configure the metric for an interface, use the isis metric interface configuration command. To restore the default metric value, use the no form of this command.
isis metric default-metric [delay-metric [expense-metric [error-metric]]] {level-1 | level-2}
no isis metric {level-1 | level-2}Syntax Description
Default
default-metric = 10
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Specifying the level-1 or level-2 keywords resets the metric only for Level 1 or Level 2 routing, respectively.
Example
In the following example, serial interface 0 is configured for a default link-state metric cost of 15 for Level 1:
interface serial 0isis metric 15 level-1Related Commands
default-information
redistributeisis password
To configure the authentication password for an interface, use the isis password interface configuration command. To disable authentication for IS-IS, use the no form of this command.
isis password password {level-1 | level-2}
no isis password {level-1 | level-2}Syntax Description
Default
Disabled
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Different passwords can be assigned for different routing levels using the level-1 and level-2 keyword arguments.
Specifying the level-1 or level-2 keywords disables the password only for Level 1 or Level 2 routing, respectively. If no keyword is specified, the default is level-1.
Example
The following example configures a password for serial interface 0 at Level 1:
interface serial 0isis password frank level-1isis priority
To configure the priority of designated routers, use the isis priority interface configuration command. To reset the default priority, use the no form of this command.
isis priority value {level-1 | level-2}
no isis priority {level-1 | level-2}Syntax Description
value
Sets the priority of a router and is a number from 0 to 127. The default value is 64.
level-1
Sets the priority for Level 1 independently.
level-2
Sets the priority for Level 2 independently.
Default
Priority of 64
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Priorities can be configured for Level 1 and Level 2 independently. Specifying the level-1 or
level-2 keywords resets priority only for Level 1 or Level 2 routing, respectively.Example
The following example shows Level 1 routing given priority by setting the priority level to 50:
interface serial 0isis priority 50 level-1isis retransmit-interval
To configure the time between retransmission of IS-IS link-state PDU (LSP) retransmission for point-to-point links, use the isis retransmit-interval interface configuration command. To restore the default value, use the no form of this command.
isis retransmit-interval seconds
no isis retransmit-interval secondsSyntax Description
Default
5 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The setting of the seconds argument should be conservative, or needless retransmission will result. The value should be larger for serial lines and virtual links.
Example
The following example configures serial interface 0 for retransmission of IS-IS LSP every 10 seconds for a large serial line:
interface serial 0isis retransmit-interval 10Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
encapsulation ppp †
frame-relay keepalive †
smds dxi †is-type
To configure the IS-IS level at which the Cisco IOS software operates, use the is-type router configuration command. To reset the default value, use the no form of this command.
is-type {level-1 | level-1-2 | level-2-only}
no is-type {level-1 | level-1-2 | level-2-only}Syntax Description
level-1
Router acts as a station router.
level-1-2
Router acts as both a station router and an area router.
level-2-only
Router acts as an area router only.
Default
Router acts as both a station router and an area router.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in IOS Release 10.3.
Example
The following example specifies an area router:
router isisis-type level-2-onlykey
To identify an authentication key on a key chain, use the key key chain configuration command. To remove the key from the key chain, use the no form of this command.
key number
no key numberSyntax Description
number
Identification number of an authentication key on a key chain. The range of keys is 0 to 2147483647. The key identification numbers need not be consecutive.
Default
No key exists on the key chain.
Command Mode
Key chain configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Currently, only RIP Version 2 uses authentication keys. It is useful to have multiple keys on a key chain so that the software can sequence through the keys as they become invalid after time, based on the accept-lifetime and send-lifetime settings.
Each key has its own key identifier, which is stored locally. The combination of the key identifier and the interface associated with the message uniquely identifies the authentication algorithm and MD5 authentication key in use. Only one authentication packet is sent, regardless of the number of valid keys. The software starts looking at the lowest key identifier number and uses the first valid key.
If the last key expires, authentication will continue and an error message will be generated. To disable authentication, you must manually delete the last valid key.
To remove all keys, remove the key chain by using the no key chain command.
Example
The following example configures a key chain called trees. The key chestnut will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key birch will be accepted from 2:30 p.m. to 4:40 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the router's set time. There is a half hour leeway on each side to handle time-of-day differences.
interface ethernet 0ip rip authentication key-chain treesip rip authentication mode md5!router ripnetwork 172.19.0.0version 2!key chain treeskey 1key-string chestnutaccept-lifetime 13:30:00 Jan 25 1996 duration 7200send-lifetime 14:00:00 Jan 25 1996 duration 3600key 2key-string birchaccept-lifetime 14:30:00 Jan 25 1996 duration 7200send-lifetime 15:00:00 Jan 25 1996 duration 3600Related Commands
accept-lifetime
key chain
key-string
send-lifetime
show key chainkey chain
To enable authentication for routing protocols, identify a group of authentication keys by using the key chain global configuration command. To remove the key chain, use the no form of this command.
key chain name-of-chain
no key chain name-of-chainSyntax Description
name-of-chain
Name of a key chain. A key chain must have at least one key, and can have up to 2147483647 keys.
Default
No key chain exists.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Currently only RIP Version 2 uses authentication keys. You must configure a key chain with keys to enable authentication on RIP packets.
You can identify multiple key chains, but it makes sense to use one key chain per interface per routing protocol. Upon specifying the key chain command, you enter key chain mode.
Example
The following example configures a key chain called trees. The key chestnut will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key birch will be accepted from 2:30 p.m. to 4:40 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the router's set time. There is a half hour leeway on each side to handle time-of-day differences.
interface ethernet 0ip rip authentication key-chain treesip rip authentication mode md5!router ripnetwork 172.19.0.0version 2!key chain treeskey 1key-string chestnutaccept-lifetime 13:30:00 Jan 25 1996 duration 7200send-lifetime 14:00:00 Jan 25 1996 duration 3600key 2key-string birchaccept-lifetime 14:30:00 Jan 25 1996 duration 7200send-lifetime 15:00:00 Jan 25 1996 duration 3600Related Commands
accept-lifetime
ip rip authentication key-chain
key
key-string
send-lifetime
show key chainkey-string
To specify the authentication string for a key, use the key-string key chain key configuration command. To remove the authentication string, use the no form of this command.
key-string text
no key-string [text]Syntax Description
Default
No key exists.
Command Mode
Key chain key configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
Currently only RIP Version 2 uses authentication keys. Each key can have only one key string.
If password encryption is configured (with the service password-encryption command), the software saves the key string as encrypted text. When you write to the terminal with the show running-config command, the software displays key-string 7 encrypted text.
Example
The following example configures a key chain called trees. The key chestnut will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key birch will be accepted from 2:30 p.m. to 4:40 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the router's set time. There is a half hour leeway on each side to handle time-of-day differences.
interface ethernet 0ip rip authentication key-chain treesip rip authentication mode md5!router ripnetwork 172.19.0.0version 2!key chain treeskey 1key-string chestnutaccept-lifetime 13:30:00 Jan 25 1996 duration 7200send-lifetime 14:00:00 Jan 25 1996 duration 3600key 2key-string birchaccept-lifetime 14:30:00 Jan 25 1996 duration 7200send-lifetime 15:00:00 Jan 25 1996 duration 3600Related Commands
A dagger (†) indicates that the command is documented outside this chapter.
accept-lifetime
key
key chain
send-lifetime
service password-encryption †
show key chainmatch as-path
To match a BGP autonomous system path access list, use the match as-path route-map configuration command. To remove a path list entry, the no form of this command.
match as-path path-list-number
no match as-path path-list-numberSyntax Description
