-
Cisco IOS IP Routing Protocols Command Reference
-
Introduction
-
BGP Commands: A through B
-
BGP Commands: C through I
-
BGP Commands: M through neighbor soo
-
BGP Commands: neighbor timers through show bgp nsap summary
-
BGP Commands: show ip bgp through T
-
EIGRP Commands: A through I
-
EIGRP Commands: M through V
-
Integrated IS-IS Commands: A through I
-
Integrated IS-IS Commands: L through V
-
On-Demand Routing Commands
-
OSPF Commands: A through ip ospf demand-circuit
-
OSPF Commands: ip ospf flood-reduction through R
-
OSPF Commands: show ip ospf through T
-
IP Routing Protocol-Independent Commands: A through R
-
IP Routing Protocol-Independent Commands: S through T
-
RIP Commands
-
Table Of Contents
default-information originate (IS-IS)
isis retransmit-throttle-interval
Integrated IS-IS Commands
advertise-passive-only
To configure Intermediate System-to-Intermediate System (IS-IS) to advertise only prefixes that belong to passive interfaces, use the advertise-passive-only command in router configuration mode. To remove the restriction, use the no form of this command.
advertise-passive-only
no advertise-passive-only
Syntax Description
This command has no arguments or keywords.
Defaults
This command has no default behavior.
Command Modes
Router configuration
Command History
Usage Guidelines
This command is an IS-IS mechanism to exclude IP prefixes of connected networks from link-state packet (LSP) advertisements, thereby reducing IS-IS convergence time.
Configuring this command per IS-IS instance is a scalable solution to reduce IS-IS convergence time because fewer prefixes will be advertised in the router nonpseudonode LSP.
This command relies on the fact that when enabling IS-IS on a loopback interface, you usually configure the loopback as passive (to prevent sending unnecessary hello packets out through it because there is no chance of finding a neighbor behind it). Thus, if you want to advertise only the loopback and if it has already been configured as passive, configuring the advertise-passive-only command per IS-IS instance would prevent the overpopulation of the routing tables.
An alternative to this command is the no isis advertise-prefix command. The no isis advertise-prefix command is a small-scale solution because it is configured per interface.
Examples
The following example uses the advertise-passive-only command, which affects the IS-IS instance, and thereby prevents advertising the IP network of Ethernet interface 0. Only the IP address of loopback interface 0 is advertised.
!interface loopback 0ip address 192.168.10.1 255.255.255.255no ip directed-broadcast!!interface Ethernet0ip address 192.168.20.1 255.255.255.0no ip directed-broadcastip router isis!.!.!.!router isispassive-interface Loopback0net 47.0004.004d.0001.0001.0c11.1111.00advertise-passive-onlylog-adjacency-changes!Related Commands
area-password
To configure the Intermediate System-to-Intermediate System (IS-IS) area authentication password, use the area-password command in router configuration mode. To disable the password, use the no form of this command.
area-password password [authenticate snp {validate | send-only}]
no area-password [password]
Syntax Description
Defaults
No area password is defined, and area password authentication is disabled.
Command Modes
Router configuration
Command History
Usage Guidelines
Using the area-password command on all routers in an area will prevent unauthorized routers from injecting false routing information into the link-state database.
This password is exchanged as plain text and thus this feature provides only limited security.
This password is inserted in Level 1 (station router level) PDU link-state packets (LSPs), complete sequence number PDUs (CSNPs), and partial sequence number PDUs (PSNP).
If you do not specify the authenticate snp keyword along with either the validate or send-only keyword, then the IS-IS routing protocol does not insert the password into SNPs.
Examples
The following example assigns an area authentication password and specifies that the password be inserted in SNPs and checked in SNPs that the system receives:
router isisarea-password track authenticate snp validateRelated Commands
domain-password
Configures the IS-IS routing domain authentication password.
isis password
Configures the authentication password for an interface.
authentication key-chain
To enable authentication for Intermediate System-to-Intermediate System (IS-IS), use the authentication key-chain command in router configuration mode. To disable such authentication, use the no form of this command.
authentication key-chain name-of-chain [level-1 | level-2]
no authentication key-chain name-of-chain [level-1 | level-2]
Syntax Description
Defaults
No key chain authentication is provided for IS-IS packets at the router level.
Command Modes
Router configuration
Command History
Usage Guidelines
If no key chain is configured with the key chain command, no key chain authentication is performed.
Key chain authentication could apply to clear text authentication or MD5 authentication. The mode is determined by the authentication mode command.
Only one authentication key chain is applied to IS-IS at one time. That is, if you configure a second authentication key-chain command, the first is overridden.
If neither the level-1 nor level-2 keyword is configured, the chain applies to both levels.
You can specify authentication for an individual IS-IS interface by using the isis authentication key-chain command.
Examples
The following example configures IS-IS to accept and send any key belonging to the key chain named site1:
router isis real_secure_networknet 49.0000.0101.0101.0101.00is-type level-1authentication mode md5 level-1authentication key-chain site1 level-1Related Commands
authentication mode
To specify the type of authentication used in Intermediate System-to-Intermediate System (IS-IS) packets for the IS-IS instance, use the authentication mode command in router configuration mode. To restore clear text authentication, use the no form of this command.
authentication mode {md5 | text} [level-1 | level-2]
no authentication mode
Syntax Description
Defaults
No authentication is provided for IS-IS packets at the router level by use of this command, although clear text (plain text) authentication could be configured by other means, such as the area-password command or the domain-password command.
Command Modes
Router configuration
Command History
Usage Guidelines
If neither the level-1 nor level-2 keyword is configured, the mode applies to both levels.
You can specify the type of authentication and the level to which it applies for a single IS-IS interface, rather than per IS-IS instance, by using the isis authentication mode command.
If you had clear text authentication configured by using the area-password or domain-password command, the authentication mode command overrides both of those commands.
If you configure the authentication mode command and subsequently try to configure the area-password or domain-password command, you will not be allowed to do so. If you truly want to configure clear text authentication using the area-password or domain-password command, you must use the no authentication mode command first.
Examples
The following example configures for the IS-IS instance that Message Digest 5 (MD5) authentication is performed on Level 1 packets:
router isis real_secure_networknet 49.0000.0101.0101.0101.00is-type level-1authentication mode md5 level-1authentication key-chain site1 level-1Related Commands
authentication send-only
To specify for the Intermediate System-to-Intermediate System (IS-IS) instance that authentication is performed only on IS-IS packets being sent (not received), use the authentication send-only command in router configuration mode. To configure for the IS-IS instance that if authentication is configured at the router level, such authentication be performed on packets being sent and received, use the no form of this command.
authentication send-only [level-1 | level-2]
no authentication send-only
Syntax Description
Defaults
If authentication is configured at the router level, it applies to IS-IS packets being sent and received.
Command Modes
Router configuration
Command History
Usage Guidelines
Use this command before configuring the authentication mode and authentication key chain so that the implementation of authentication goes smoothly. That is, the routers will have more time for the keys to be configured on each router if authentication is inserted only on the packets being sent, not checked on packets being received. After all of the routers that must communicate are configured with this command, enable the authentication mode and key chain on each router. Then specify the no authentication send-only command to disable the send-only feature.
If neither the level-1 nor level-2 keyword is configured, the send-only feature applies to both levels.
This command could apply to clear text authentication or Message Digest 5 (MD5) authentication. The mode is determined by the authentication mode command.
Examples
The following example configures IS-IS Level 1 packets to use clear text authentication on packets being sent (not received):
router isis real_secure_networknet 49.0000.0101.0101.0101.00is-type level-1authentication send-only level-1authentication mode text level-1authentication key-chain site1 level-1Related Commands
clear isis lsp-full
To clear the LSPFULL state, use the clear isis lsp-full command in privileged EXEC mode.
clear isis lsp-full
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
If the link-state PDU (LSP) becomes full because too many routes are redistributed, use the clear isis lsp-full command to clear the state after the problem has been resolved.
Examples
This example clears the LSPFULL state:
Router# clear isis lsp-fullRelated Commands
lsp-full suppress
Controls which routes are suppressed when the link-state PDU becomes full.
clear isis rib redistribution
To clear some or all prefixes in the Intermediate System-to-Intermediate System (IS-IS) redistribution cache, use the clear isis rib redistribution command in privileged EXEC mode.
clear isis rib redistribution [level-1 | level-2] [network-prefix] [network-mask]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
We recommend that you use this command in a troubleshooting situation only when a Cisco Technical Assistance Center representative requests you to do so following a software error.
Examples
The following example clears the network prefix 10.1.0.0 from the IP local redistribution cache:
Router# clear isis rib redistribution 10.1.0.0 255.255.0.0Related Commands
debug isis rib redistribution
Debugs the local redistribution cache event.
show isis rib redistribution
Displays the prefixes in the IS-IS redistribution cache.
default-information originate (IS-IS)
To generate a default route into an Intermediate System-to-Intermediate System (IS-IS) routing domain, use the default-information originate command in router configuration mode. 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.
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
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 link-state packets (LSPs).
Without a route map, the default is advertised only in Level 2 LSPs. For Level 1 routing, there is another mechanism to find the default route, which is to look for the closest Level 1 or Level 2 router. The closest Level 1 or Level 2 router can be found by looking at the attached-bit (ATT) in Level 1 LSPs.
A route map can be used for two purposes:
•
Make the router generate default in its Level 1 LSPs.
•
With a match ip address standard-access-list command, you can specify one or more IP routes that must exist before the router will advertise 0/0.
Examples
The following example forces the software 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 10.105.0.0access-list 2 permit 10.105.0.0 0.0.255.255Related Commands
domain-password
To configure the Intermediate System-to-Intermediate System (IS-IS) routing domain authentication password, use the domain-password command in router configuration mode. To disable a password, use the no form of this command.
domain-password password [authenticate snp {validate | send-only}]
no domain-password [password]
Syntax Description
Defaults
No domain password is specified and no authentication is enabled for exchange of Level 2 routing information.
Command Modes
Router configuration
Command History
Usage Guidelines
This password is exchanged as plain text and thus this feature provides only limited security.
This password is inserted in Level 2 (area router level) PDU link-state packets (LSPs), complete sequence number PDUs (CSNPs), and partial sequence number PDUs (PSNPs).
If you do not specify the authenticate snp keyword along with either the validate or send-only keyword, then the IS-IS routing protocol does not insert the password into SNPs.
Examples
The following example assigns an authentication password to the routing domain and specifies that the password be inserted in SNPs and checked in SNPs that the system receives:
router isisdomain-password users2j45 authenticate snp validateRelated Commands
area-password
Configures the IS-IS area authentication password.
isis password
Configures the authentication password for an interface.
fast-flood
To fast-flood Intermediate System-to-Intermediate System (IS-IS) link-state packets (LSPs), use the fast-flood command in router configuration mode. To disable the fast-flooding, use the no version of this command.
fast-flood lsp-number
no fast-flood lsp-number
Syntax Description
lsp-number
(Optional) The number of LSPs from 1 to 15 to be flooded before shortest path first (SPF) is started. The default is 5 LSPs.
Defaults
Fast-flooding is disabled. Five LSPs are flooded before SPF is started.
Command Modes
Router configuration
Command History
12.0(27)S
This command was introduced.
12.3(7)T
This command was integrated into Cisco IOS Release 12.3(7)T. This command replaces the ip fast-convergence command.
Usage Guidelines
The fast-flood command tells the router to flood a certain number of LSPs, as configured by the lsp-number argument (if no lsp-number value has been specified, the default value of 5 is used), that invoke SPF before running SPF. When you speed up the LSP flooding process, you improve overall network convergence time.
If you are running SPF and if you have configured very short values (less than 40 milliseconds) for the initial delay that is set by the seconds argument of the incremental-spf command, the SPF computation might start before the LSP that triggered SPF is flooded to neighbors. The router should always flood (at least) the LSP that triggered SPF before the router runs the SPF computation.
We recommend that you enable the fast-flooding of LSPs before the router runs the SPF computation, in order to achieve a faster convergence time.
Note
Examples
In the following example, the fast-flood command is entered to configure the router to flood the first seven LSPs that invoke SPF, before the SPF computation is started. When the show running-configuration command is entered, the output confirms that fast-flooding has been enabled on the router.
Router# clear isis rib redistribution 10.1.0.0 255.255.0.0Router> enableRouter# configure terminalRouter(config)# router isis firstRouter(config-router)# fast-flood 7Router(config-router)# endRouter# show running-configfast-flood 7Related Commands
hello padding
To reenable IS-IS hello padding at the router level, enter the hello padding command in router configuration mode. To disable IS-IS hello padding, use the no form of this command.
hello padding
no hello padding
Syntax Description
This command has no arguments or keywords.
Defaults
IS-IS hello padding is enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
Intermediate System-to-Intermediate System (IS-IS) hellos are padded to the full maximum transmission unit (MTU) size. The benefit of padding IS-IS hellos to the full MTU is that it allows for early detection of errors that result from transmission problems with large frames or errors that result from mismatched MTUs on adjacent interfaces.
You can disable hello padding in order to avoid wasting network bandwidth in case the MTU of both interfaces is the same or, in case of translational bridging. While hello padding is disabled, Cisco routers still send the first five IS-IS hellos padded to the full MTU size, in order to maintain the benefits of discovering MTU mismatches.
To disable hello padding for all interfaces on a router for the IS-IS routing process, enter the no hello padding command in router configuration mode. To selectively disable hello padding for a specific interface, enter the no isis hello padding command in interface configuration mode.
Examples
In the following example the no hello padding command is used to turn off hello padding at the router level:
Router(config)# router isisRouter(config-router)# no hello paddingRouter(config-router)# endThe show clns interfaces command is entered to show that hello padding has been turned off at router level:
Router# show clns interface e0/0Ethernet0/0 is up, line protocol is upChecksums enabled, MTU 1497, Encapsulation SAPERPDUs enabled, min. interval 10 msec.CLNS fast switching enabledCLNS SSE switching disabledDEC compatibility mode OFF for this interfaceNext ESH/ISH in 4 secondsRouting Protocol: IS-ISCircuit Type: level-1-2Interface number 0x0, local circuit ID 0x1Level-1 Metric: 10, Priority: 64, Circuit ID: Router_B.01Level-1 IPv6 Metric: 10Number of active level-1 adjacencies: 1Level-2 Metric: 10, Priority: 64, Circuit ID: Router_B.01Level-2 IPv6 Metric: 10Number of active level-2 adjacencies: 1Next IS-IS LAN Level-1 Hello in 6 seconds! No hello paddingNext IS-IS LAN Level-2 Hello in 2 seconds! No hello paddingWhen the debug isis adj packets command is entered, the output will show the IS-IS hello protocol data unit (PDU) length when a hello packet has been sent to or received from an IS-IS adjacency. In the following example the IS-IS hello PDU length is 1497:
Router# debug isis adj packets e0/0IS-IS Adjacency related packets debugging is onRouter_A#*Oct 11 18:04:17.455: ISIS-Adj: Sending L1 LAN IIH on Ethernet0/0, length 55*Oct 11 18:04:19.075: ISIS-Adj: Rec L2 IIH from aabb.cc00.6600 (Ethernet0/0), cir type L1L2, cir id 0000.0000.000B.01, length 1497Related Commands
hostname dynamic
To enable IS-IS dynamic hostname capability on the router, use the hostname dynamic command in router configuration mode. To disable the dynamic hostname feature, use the no form of this command.
hostname dynamic
no hostname dynamic
Syntax Description
This command has no arguments or keywords.
Command Default
The dynamic hostname feature is enabled by default.
Command Modes
Router configuration
Command History
12.0
This command was introduced.
12.0S
This command was integrated into Cisco IOS Release 12.0(S).
Usage Guidelines
In the IS-IS routing domain, the system ID is used to represent each router. The system ID is part of the network entity title (NET) that is configured for each IS-IS router. For example, a router with a configured NET of 49.0001.0023.0003.000a.00 has a system ID of 0023.0003.000a. Router-name-to-system-ID mapping is difficult for network administrators to remember during maintenance and troubleshooting on the routers. Entering the show isis hostname command displays the entries in the system-ID-to-router-name mapping table.
The dynamic hostname mechanism uses link-state protocol (LSP) flooding to distribute the router-name-to-system-ID mapping information across the entire network. Every router on the network will try to install the system ID-to-router name mapping information in its routing table.
If a router that has been advertising the dynamic name type, length, value (TLV) on the network suddenly stops the advertisement, the mapping information last received will remain in the dynamic host mapping table for up to one hour, allowing the network administrator to display the entries in the mapping entry during a time when the network experiences problems. Entering the show isis hostname command displays the entries in the mapping table.
Note
Examples
The following example changes the hostname from Router to RouterA and assigns the NET 49.0001.0000.0000.000b.00 to RouterA. The dynamic hostname feature is disabled by entering the no dynamic hostname command. The dynamic hostname feature is then reeanabled by entering the dynamic hostname command.
Router> enableRouter# configure terminalRouter(config)# hostname RouterARouterA(config)# router isis CompanyARouterA(config-router)# net 49.0001.0000.0000.000b.00RouterA(config-router)# hostname dynamicRouterA(config-router)# endEntering the show isis hostname command displays the dynamic host mapping table. The * symbol signifies that this is the hostname for the local router. The dynamic host mapping table confirms that system ID 0000.0000.000B belongs to a router with the dynamic hostname RouterA. This router is running the IS-IS process named CompanyA.
Router# show isis hostnameLevel System ID Dynamic Hostname (CompanyA)* 0000.0000.000B RouterARelated Commands
ip fast-convergence
To reduce packet loss when the metric of a path is changed, or to fast-flood Intermediate System-to-Intermediate System (IS-IS) link-state packets (LSPs), use the ip fast-convergence command in router configuration mode. To disable packet loss reduction or fast-flooding, use the no version of this command.
ip fast-convergence
no ip fast-convergence
Note
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
To reduce packet loss when the metric of a path is changed, use the ip fast-convergence command. Entering the ip fast-convergence command is especially helpful when Multiprotocol Label Switching (MPLS) traffic engineering with Fast Reroute (FRR) is deployed.
If you are running Cisco IOS Release 12.2(11)T or a later release, you can enter the ip fast-convergence command to configure the router to flood the first five LSPs that invoke shortest path first (SPF) before running SPF. When you speed up the LSP flooding process, you improve overall network convergence time. We recommend that you enable the fast-flooding of LSPs before the router runs the SPF computation, in order to achieve a faster convergence time.
Examples
In the following example, the ip fast-convergence command is entered to configure the router to flood the first five LSPs that invoke SPF, before the SPF computation is started. When the show running-configuration command is entered, the output confirms that fast-flooding has been enabled on the router.
Router> enableRouter# configure terminalRouter(config)# router isisRouter(config-router)# ip fast-convergenceRouter(config-router)# endRouter# show running-configfast-floodRelated Commands
ip route priority high
To assign a high priority to an Integrated Intermediate System-to-Intermediate System (IS-IS) IP prefix, use the ip route priority high command in router configuration mode. To remove the IP prefix priority, use the no form of this command.
ip route priority high tag tag-value
no ip route priority high tag tag-value
Syntax Description
tag tag-value
Assigns a high priority to IS-IS IP prefixes with a specific route tag in a range from 1 to 4294967295.
Defaults
No IP prefix priority is set.
Command Modes
Router configuration
Command History
Usage Guidelines
When you use the ip route priority high command to tag higher priority IS-IS IP prefixes for faster processing and installation in the global routing table, you can achieve faster convergence. For example, you can help Voice over IP (VoIP) gateway addresses get processed first to help VoIP traffic get updated faster than other types of packets.
Examples
The following example uses the ip route priority high command to assign a tag value of 100 to the IS-IS IP prefix:
Router> enableRouter# configure terminalRouter(config)# interface Ethernet 0Router(config-if)# ip router isisRouter(config-if)# isis tag 100!Router(config)# router isisRouter(config-router)# ip route priority high tag 100!Related Commands
ip router isis
To configure an Intermediate System-to-Intermediate System (IS-IS) routing process for IP on an interface and to attach an area designator to the routing process, use the ip router isis command in interface configuration mode. To disable IS-IS for IP, use the no form of the command.
ip router isis area-tag
no ip router isis area-tag
Syntax Description
Defaults
No routing processes are specified.
Command Modes
Interface configuration
Command History
Usage Guidelines
Before the IS-IS routing process is useful, a network entity title (NET) must be assigned with the net command and some interfaces must have IS-IS enabled.
If you have IS-IS running and at least one International Organization for Standardization Interior Gateway Routing Protocol (ISO-IGRP) process, the IS-IS process and the ISO-IGRP process cannot both be configured without an area tag. The null tag can be used by only one process. If you run ISO-IGRP and IS-IS, a null tag can be used for IS-IS, but not for ISO-IGRP at the same time. However, each area in an IS-IS multiarea configuration should have a nonnull area tag to facilitate identification of the area.
You can configure only one process to perform Level 2 (interarea) routing. If Level 2 routing is configured on any process, all additional processes are automatically configured as Level 1. You can configure this process to perform intra-area (Level 1) routing at the same time. You can configure up to 29 additional processes as Level 1-only processes. Use the is-type command to remove Level 2 routing from a router instance. You can then use the is-type command to enable Level 2 routing on some other IS-IS router instance.
An interface cannot be part of more than one area, except in the case where the associated routing process is performing both Level 1 and Level 2 routing. On media such as WAN media where subinterfaces are supported, different subinterfaces could be configured for different areas.
Examples
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 Ethernet interface 0 and serial interface 0:
router isis Financenet 49.0001.aaaa.aaaa.aaaa.00interface Ethernet 0ip router isis Financeinterface serial 0ip router isis FinanceThe following example shows an IS-IS configuration with two Level 1 areas and one Level 1-2 area:
ip routing...interface Tunnel529ip address 10.0.0.5 255.255.255.0ip router isis BBinterface Ethernet1ip address 10.1.1.5 255.255.255.0ip router isis A3253-01!interface Ethernet2ip address 10.2.2.5 255.255.255.0ip router isis A3253-02...
