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
