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Cisco IOS XR Routing Command Reference, Release 3.4
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Preface
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BGP Commands on Cisco IOS XR Software
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EIGRP Commands on Cisco IOS XR Software
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IS-IS Commands on Cisco IOS XR Software
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OSPF Commands on Cisco IOS XR Software
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OSPFv3 Commands on Cisco IOS XR Software
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RIB Commands on Cisco IOS XR Software
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RIP Commands on Cisco IOS XR Software
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Routing Policy Language Commands on Cisco IOS XR Software
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Static Routing Commands on Cisco IOS XR Software
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Index
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Table Of Contents
BGP Commands on Cisco IOS XR Software
bgp auto-policy-soft-reset disable
bgp bestpath cost-community ignore
bgp bestpath med missing-as-worst
bgp client-to-client reflection disable
bgp fast-external-fallover disable
bgp graceful-restart graceful-reset
bgp graceful-restart purge-time
bgp graceful-restart restart-time
bgp graceful-restart stalepath-time
bgp log neighbor changes disable
clear bgp nexthop performance-statistics
clear bgp nexthop registration
clear bgp performance-statistics
default-information originate (BGP)
show bgp truncated-communities
BGP Commands on Cisco IOS XR Software
This chapter describes the commands used to configure and monitor Border Gateway Protocol (BGP) for IP Version 4 (IPv4), IP Version 6 (IPv6), and Virtual Private Network Version 4 (VPNv4) routing sessions.
For detailed information about BGP concepts, configuration tasks, and examples, see Implementing BGP on Cisco IOS XR Software.
address-family (BGP)
To enter various address family configuration modes while configuring Border Gateway Protocol (BGP), use the address-family command in an appropriate configuration mode. To disable support for an address family, use the no form of this command.
address-family {ipv4 unicast | ipv4 multicast | ipv4 labeled-unicast | ipv6 unicast | ipv6 multicast | vpnv4 unicast}
no address-family {ipv4 unicast | ipv4 multicast | ipv4 labeled-unicast | ipv6 unicast | ipv6 multicast | vpnv4 unicast}
Syntax Description
Defaults
An address family must be explicitly configured in the router configuration mode for the address family to be active in BGP. Similarly, an address family must be configured under the neighbor for the BGP session to be established for that address family. An address family must be configured in router configuration mode before it can be configured under a neighbor.
Command Modes
Router configuration
Neighbor configuration
Neighbor group configuration
VRF configuration
VRF neighbor configuration (IPv4 address families)Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the address-family command to enter various address family configuration modes while configuring BGP routing sessions. When you enter the address-family command from router configuration mode, you enable the address family and enter global address family configuration mode.
When you enter the address-family command from neighbor configuration mode, you activate the address family on the neighbor and enter neighbor address family configuration mode.
IPv4 neighbor sessions support IPv4 unicast, multicast, labeled-unicast, and VPNv4 unicast address families. IPv6 neighbor sessions support IPv6 unicast and multicast address families.
Note
It is not necessary to have an address family configured in router configuration mode for either an IPv4 or IPv6 neighbor to be configured. However, to be able to configure an address family under a neighbor, the same address family must be configured in router configuration mode. It is not possible to bring up a session for a neighbor under a specific address family unless the address family is configured for the neighbor.
Task ID
Examples
The following example shows how to place the router in global address family configuration mode for the IPv4 address family:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)#The following example shows how to activate IPv4 multicast for neighbor 10.0.0.1 and place the router in neighbor address family configuration mode for the IPv4 multicast address family:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-af)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)#advertisement-interval
To set the minimum interval between the sending of Border Gateway Protocol (BGP) routing updates, use the advertisement-interval command in an appropriate configuration mode. To remove the advertisement-interval command from the configuration file and restore the system to its default interval values, use the no form of this command.
advertisement-interval seconds
no advertisement-interval [seconds]
Syntax Description
Defaults
Default minimum interval:
For internal BGP (iBGP) peers is 0 seconds
For external BGP (eBGP) peers is 30 seconds
For customer edge (CE) peers is 0 secondsCommand Modes
Neighbor configuration
Neighbor group configuration
Session group configuration
VRF neighbor configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If this command configures a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Task ID
Examples
The following example shows how to set the minimum time between sending BGP routing updates to 10 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 5RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.1.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 100RP/0/RP0/CPU0:router(config-bgp-nbr)# advertisement-interval 10Related Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
af-group
To create an address family group for Border Gateway Protocol (BGP) neighbors and enter address family group configuration mode, use the af-group command in router configuration mode. To remove an address family group, use the no form of this command.
af-group af-group-name address-family {ipv4 unicast | ipv4 multicast | ipv4 labeled-unicast | ipv6 unicast | ipv6 multicast | vpnv4 unicast}
no af-group af-group-name address-family {ipv4 unicast | ipv4 multicast | ipv4 labeled-unicast | ipv6 unicast | ipv6 multicast | vpnv4 unicast}
Syntax Description
Defaults
No BGP address family group is configured.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the af-group command to group address family-specific neighbor commands within an IPv4 or IPv6 address family. Neighbors that have address family configuration are able to use the address family group. Further, neighbors inherit the configuration parameters of the entire address family group.
You cannot define two address family groups with the same name in different address families.
Task ID
Examples
The following example shows how to create address family group group1 and enter address family group configuration mode for IPv4 unicast. Group1 contains the next-hop-self feature, which is inherited by neighbors that use address family group1.
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# next-hop-selfRelated Commands
aggregate-address
To create an aggregate entry in a Border Gateway Protocol (BGP) routing table, use the aggregate-address command in an appropriate configuration mode. To remove the aggregate-address command from the configuration file and restore the system to its default condition, use the no form of this command.
aggregate-address address/mask-length [as-set] [as-confed-set] [summary-only] [route-policy route-policy-name]
no aggregate-address address/mask-length [as-set] [as-confed-set] [summary-only] [route-policy route-policy-name]
Syntax Description
Defaults
When you do not specify this command, no aggregate entry is created in the BGP routing table.
Command Modes
IPv4 address family configuration
IPv6 address family configuration
VRF IPv4 address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
You can implement aggregate routing in BGP either by redistributing an aggregate route into BGP using the network command or the aggregate-address command.
Use the aggregate-address command without optional arguments to create an aggregate entry in the BGP routing table if any more-specific BGP routes are available that fall in the specified range. The aggregate route is 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.)
Use of the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword. However, the advertised path for this route is an AS_SET, a set of all autonomous systems contained in all paths that are being summarized.
Do not use this form of the aggregate-address command when aggregating many paths because this route must be continually withdrawn and updated as autonomous system path reachability information for the summarized routes changes.
Use the as-confed-set keyword to create an AS_CONFED_SET in the autonomous system path of the aggregate from any confederation segments in the paths being summarized. This keyword takes effect only if the as-set keyword is also specified.
Use of the summary-only keyword creates an aggregate entry (for example, 10.0.0.0/8) but suppresses advertisements of more-specific routes to all neighbors. If you want to suppress only advertisements to certain neighbors, use the route-policy (BGP) command in neighbor address family configuration mode with caution. If a more-specific route leaks out, all BGP speakers (the local router) prefer that route over the less-specific aggregate you generate (using longest-match routing).
Use the route-policy keyword to specify a routing policy for the aggregate entry. The route-policy keyword is used to select which more-specific information to base the aggregate entry on and which more-specific information to suppress. You can also use the keyword to modify the attributes of the aggregate entry.
Task ID
Examples
The following example shows how to create an aggregate address. The path advertised for this route is an autonomous system set consisting of all elements contained in all paths that are being summarized.
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# aggregate-address 10.0.0.0/8 as-setRelated Commands
allocate-label
To allocate Multiprotocol Label Switching (MPLS) labels for specific IPv4 unicast or VPN routing and forwarding (VRF) IPv4 unicast routes so that the BGP router can send labels with BGP routes to a neighboring router configured for labeled-unicast sessions, use the allocate-label command in the appropriate configuration mode. To restore the system to its default condition, use the no form of this command.
allocate-label {route-policy route-policy-name | all}
no allocate-label {route-policy route-policy-name | all}
Syntax Description
Defaults
No default behavior or values
Command Modes
IPv4 address family configuration
VRF IPv4 address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the allocate-label command with a route policy to trigger BGP to allocate labels for all or a filtered set of global IPv4 routes (as dictated by the route policy). The command enables autonomous system border routers (ASBRs) that have labeled IPv4 unicast sessions to exchange Multiprotocol Label Switching (MPLS) labels with the IPv4 routes to the other autonomous system (AS) in Layer 3 Virtual Private Network (L3VPN) inter-AS deployments.
Note
See Cisco IOS XR Multiprotocol Label Switching Configuration Guide for information on using the allocate-label command for L3VPN inter-AS deployments and carrier-supporting-carrier IPv4 BGP label distribution.
Task ID
Examples
The following example shows how to enable allocating labels for IPv4 routes:
RP/0/0/CPU0:router(config)# router bgp 6RP/0/0/CPU0:router(config-bgp)# address family ipv4 unicastRP/0/0/CPU0:router(config-bgp-af)# allocate-label route-policy policy_Aallowas-in
To allow an AS path with the provider edge (PE) autonomous system number (ASN) a specified number of times, use the allowas-in command in an appropriate configuration mode. To restore the system to its default condition, use the no form of this command.
allowas-in [as-occurrence-number]
no allowas-in [as-occurrence-number]
Syntax Description
Defaults
No default behavior or values
Command Modes
Address family group configuration
Neighbor address family configurationCommand History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Hub and spoke VPN networks require looping back of routing information to the hub PE through the hub customer edge (CE). See Cisco IOS XR Multiprotocol Label Switching Configuration Guide for information on hub and spoke VPN networks. This looping back, in addition to the presence of the PE ASN, causes the looped-back information to be dropped by the hub PE.
The allowas-in command prevents the looped-back information from being dropped by replacing the neighbor autonomous system number (ASN) with the PE ASN in the AS path. This allows the VPN customer to see a specified number of occurrences of the PE ASN in the AS path.
Task ID
Examples
The following example shows how to allow five occurrences of the PE ASN:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# af-group group_1 address-family vpnv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# allowas-in 5as-override
To configure a provider edge (PE) router to override the autonomous system number (ASN) of a site with the ASN of a provider, use the as-override command in VRF neighbor address family configuration mode. To restore the system to its default condition, use the no form of this command.
as-override [disable]
no as-override [disable]
Syntax Description
Defaults
Automatic override of the ASN is disabled.
Command Modes
VRF neighbor address family configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the as-override command in conjunction with the site-of-origin (SoO) feature, identifying the site where a route originated, and preventing routing loops between routers within a VPN.
Task ID
Examples
The following example shows how to configure an ASN override:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# vrf vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)# neighbor 192.168.70.24RP/0/RP0/CPU0:router(config-bgp-vrf-nbr)# remote-as 10RP/0/RP0/CPU0:router(config-bgp-vrf-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-vrf-nbr-af)# as-overrideRelated Commands
bgp as-path-loopcheck
To enable an autonomous system path for loop checking internal Border Gateway Protocol (iBGP) peers, use the bgp as-path-loopcheck command in an appropriate configuration mode. To restore the system to its default condition, use the no form of this command.
bgp as-path-loopcheck
no bgp as-path-loopcheck
Syntax Description
This command has no arguments or keywords.
Defaults
When you do not specify this command, loop checking is performed only for external peers.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to configure an autonomous system path for loop checking iBGP peers:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# bgp as-path-loopcheckbgp attribute-download
To enable Border Gateway Protocol (BGP) attribute download, use the bgp attribute-download command in an appropriate configuration mode. To disable BGP attribute download, use the no form of this command.
bgp attribute-download
no bgp attribute-download
Syntax Description
This command has no arguments or keywords.
Defaults
BGP attribute download is not enabled.
Command Modes
IPv4 unicast address family configuration
Command History
Release 3.2
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.3.0
No modification.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
When BGP attribute download is enabled using the bgp attribute-download command, BGP reinstalls all routes whose attributes are not currently in the RIB. Likewise, if the user disables BGP attribute download using the no form of the command, BGP reinstalls previously installed routes with a null key, and removes the attributes from the RIB.
Use the bgp attribute-download command to enable the Netflow BGP data export function. When attribute download is enabled, BGP downloads the attribute information for prefixes (community, extended community, and as-path) to the Routing Information Base (RIB) and Forwarding Information Base (FIB). This enables FIB to associate the prefixes with attributes and send the Netflow statistics along with the associated attributes.
Task ID
Examples
The following example shows the BGP routes before and after BGP attribute download is enabled and shows how to enable BGP attribute download on BGP router 50:
RP/0/RP0/CPU0:router# show route bgpB 100.0.1.0/24 [200/0] via 10.0.101.1, 00:00:37B 100.0.2.0/24 [200/0] via 10.0.101.1, 00:00:37B 100.0.3.0/24 [200/0] via 10.0.101.1, 00:00:37B 100.0.4.0/24 [200/0] via 10.0.101.1, 00:00:37B 100.0.5.0/24 [200/0] via 10.0.101.1, 00:00:37RP/0/RP0/CPU0:router(config)# router bgp 50RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp attribute-download!!!RP/0/RP0/CPU0:router# show route bgpB 100.0.1.0/24 [200/0] via 10.0.101.1, 00:00:01Attribute ID 0x2B 100.0.2.0/24 [200/0] via 10.0.101.1, 00:00:01Attribute ID 0x2B 100.0.3.0/24 [200/0] via 10.0.101.1, 00:00:01Attribute ID 0x2B 100.0.4.0/24 [200/0] via 10.0.101.1, 00:00:01Attribute ID 0x2B 100.0.5.0/24 [200/0] via 10.0.101.1, 00:00:01Attribute ID 0x2bgp auto-policy-soft-reset disable
To disable an automatic reset of Border Gateway Protocol (BGP) peers when their configured route policy is modified, use the bgp auto-policy-soft-reset disable command in an appropriate configuration mode. To re-enable automatic soft reset of BGP peers, use the no form of this command.
bgp auto-policy-soft-reset disable
no bgp auto-policy-soft-reset disable
Syntax Description
This command has no arguments or keywords.
Defaults
Automatic soft reset of peers is enabled.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Note
Task ID
Examples
The following example shows how to disable an automatic soft reset of BGP peers when their configured route policy is modified:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# bgp auto-policy-soft-reset disablebgp bestpath as-path ignore
To ignore the autonomous system path length when calculating preferred paths, use the bgp bestpath as-path ignore command in an appropriate configuration mode. To return the software to the default state in which it considers the autonomous system path length when calculating preferred paths, use the no form of this command.
bgp bestpath as-path ignore
no bgp bestpath as-path ignore
Syntax Description
This command has no arguments or keywords.
Defaults
The autonomous system path length is used (not ignored) when a best path is selected.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp bestpath as-path ignore command to ignore the length of autonomous system paths when the software selects a preferred path. When the best path is selected, if this command is specified, all steps are performed as usual except comparison of the autonomous path length between candidate paths.
Task ID
Examples
The following example shows how to configure the software to ignore the autonomous system length when performing best-path selection:
RP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath as-path ignoreRelated Commands
bgp bestpath compare-routerid
To compare identical routes received from external BGP (eBGP) peers during the best-path selection process and select the route with the lowest router ID, use the bgp bestpath compare-routerid command in an appropriate configuration mode. To disable comparing identical routes received from eBGP peers during best-path selection, use the no form of this command.
bgp bestpath compare-routerid
no bgp bestpath compare-routerid
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not select a new best path if it is the same as the current best path (according to the BGP selection algorithm) except for the router ID.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp bestpath compare-routerid command to affect how the software selects the best path, in the case where there are two paths of equal cost according to the BGP selection algorithm. This command is used to force the software to select the path with the lower router ID as the best path. If this command is not used, the software continues to use whichever path is currently the best path, regardless of which has the lower router ID.
Task ID
Examples
The following example shows how to configure the BGP speaker in autonomous system 500 to compare the router IDs of similar paths:
RP/0/RP0/CPU0:router(config)# router bgp 500RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath compare-routeridRelated Commands
bgp bestpath cost-community ignore
To configure a router that is running the Border Gateway Protocol (BGP) to not evaluate the cost community attribute during the best-path selection process, use the bgp bestpath cost-community ignore command in an appropriate configuration mode. To restore the system to its default condition, use the no form of this command.
bgp bestpath cost-community ignore
no bgp bestpath cost-community ignore
Syntax Description
This command has no arguments or keywords.
Defaults
The behavior of this command is enabled by default until the cost community attribute is manually configured.
Command Modes
Router configuration
VRF configurationCommand History
Release 3.3.0
This command was first supported on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp bestpath cost-community ignore command to disable the evaluation of the cost community attribute to help isolate problems and troubleshoot issues that relate to BGP path selection. This command can also be used to delay the activation of cost community attribute evaluation so that cost community filtering can be deployed in a large network at the same time.
Task ID
Examples
The following example shows how to configure a router to not evaluate the cost community attribute during the best-path selection process:
RP/0/RP0/CPU0:router(config)# router bgp 500RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath cost-community ignoreRelated Commands
bgp bestpath med always
To allow the comparison of the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems, use the bgp bestpath med always command in an appropriate configuration mode. To disable considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med always
no bgp bestpath med always
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not compare MEDs for paths from neighbors in different autonomous systems.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The MED is one of the parameters that is considered by the software when selecting the best path among many alternative paths. The software chooses the path with the lowest MED.
By default, during the best-path selection process, the software makes a MED comparison only among paths from the same autonomous system. This command changes the default behavior of the software by allowing comparison of MEDs among paths regardless of the autonomous system from which the paths are received.
When the bgp bestpath med always command is not enabled and distributed BGP is configured, speakers calculate partial best paths only (executes the best-path steps up to the MED comparison) and send them to BGP Routing Information Base (bRIB). bRIB calculates the final best path (executes all the steps in the best-path calculation). When the bgp bestpath med always command is enabled and distributed BGP is configured, speakers can compare the MED across all ASs, allowing the speaker to calculate a single best path to send it to bRIB. bRIB is the ultimate process that calculates the final best path, but when the bgp bestpath med always command is enabled, the speakers send a single best path instead of potentially sending multiple, partial best paths
Task ID
Examples
The following example shows how to configure the Border Gateway Protocol (BGP) speaker in autonomous system 100 to compare MEDs among alternative paths, regardless of the autonomous system from which the paths are received:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med alwaysRelated Commands
bgp bestpath med confed
To enable Multi Exit Discriminator (MED) comparison among paths learned from confederation peers, use the bgp bestpath med confed command in an appropriate configuration mode. To disable the software from considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med confed
no bgp bestpath med confed
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not compare the MED of paths containing only confederation segments, or paths containing confederation segments followed by an AS_SET, with the MED of any other paths.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, the MED of the following paths is not compared with the MED of any other path:
•
•
•
•
Use the bgp bestpath med confed command to affect how the following types of paths are treated in the BGP best-path algorithm:
•
•
The MED for paths that start with an AS_SEQUENCE or that start with confederation segments followed by an AS_SEQUENCE only is compared with the MED of other paths that share the same first autonomous system number in the autonomous system sequence (the neighbor autonomous system number). This behavior is not affected by the bgp bestpath med confed command.
As an example, suppose that autonomous systems 65000, 65001, 65002, and 65004 are part of a confederation, but autonomous system 1 is not. Suppose that for a particular route, the following paths exist:
•
•
•
If the bgp bestpath med confed command is enabled, the software selects path 1 as the best path because it:
•
•
The MED is not compared with path 3 because it has an external autonomous system number (that is, an AS_SEQUENCE) in the path. If the bgp bestpath med confed command is not enabled, then MED is not compared between any of these paths. Consequently, the software selects path 2 as the best path because it has the lowest IGP metric.
Task ID
Examples
The following command shows how to enable Border Gateway Protocol (BGP) software to compare MED values for paths learned from confederation peers:
RP/0/RP0/CPU0:router(config)# router bgp 210RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med confedRelated Commands
bgp bestpath med missing-as-worst
To have the software consider a missing Multi Exit Discriminator (MED) attribute in a path as having a value of infinity, making the path without a MED value the least desirable path, use the bgp bestpath med missing-as-worst command in an appropriate configuration mode. To disable considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med missing-as-worst
no bgp bestpath med missing-as-worst
Syntax Description
This command has no arguments or keywords.
Defaults
The software assigns a value of 0 to the missing MED, causing the path with the missing MED attribute to be considered as the best possible MED.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to direct the Border Gateway Protocol (BGP) software to consider a missing MED attribute in a path as having a value of infinity, making this path the least desirable path:
RP/0/RP0/CPU0:router(config)# router bgp 210RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med missing-as-worstRelated Commands
bgp client-to-client reflection disable
To disable reflection of routes between route-reflection clients using a Border Gateway Protocol (BGP) route reflector, use the bgp client-to-client reflection disable command in address family configuration mode. To re-enable client-to-client reflection, use the no form of this command.
bgp client-to-client reflection disable
no bgp client-to-client reflection disable
Syntax Description
This command has no arguments or keywords.
Defaults
Client-to-client reflection is enabled.
Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
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.
Examples
In this example, the three neighbors are fully meshed, so client-to-client reflection is disabled:
RP/0/RP0/CPU0:router(config)# router bgp 65534RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp client-to-client reflection disableRP/0/RP0/CPU0:router(config-bgp-af)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group rrclientsRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 65534RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# route-reflector-clientRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exitRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.253.21 use neighbor-group rrclientsRP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.253.22 use neighbor-group rrclientsRelated Commands
bgp cluster-id
To configure the cluster ID if the Border Gateway Protocol (BGP) cluster has more than one route reflector, use the bgp cluster-id command in an appropriate configuration mode. To remove the cluster ID, use the no form of this command.
bgp cluster-id cluster-id
no bgp cluster-id [cluster-id]
Syntax Description
cluster-id
Cluster ID of this router acting as a route reflector; maximum of 4 bytes. Cluster ID can be entered either as an IP address or value. Range is 1 to 4294967295.
Defaults
A cluster ID is not configured.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Together, a route reflector and its clients form a cluster. A cluster of clients usually has a single route reflector. In such instances, the cluster is identified by the software as the router ID of the route reflector. To increase redundancy and avoid a single point of failure in the network, a cluster might have more than one route reflector. If it does, all route reflectors in the cluster must be configured with the same 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 the bgp cluster-id command to configure the cluster ID.
Task ID
Examples
The following example shows how to configure the local router as one of the route reflectors serving the cluster. It is configured with the cluster ID to identify the cluster.
RP/0/RP0/CPU0:router(config)# router bgp 65534RP/0/RP0/CPU0:router(config-bgp)# bgp cluster-id 192.168.70.1RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.70.24RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 65534RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-reflector-clientRelated Commands
bgp confederation identifier
To specify a Border Gateway Protocol (BGP) confederation identifier, use the bgp confederation identifier command in an appropriate configuration mode. To remove the confederation identifier, use the no form of this command.
bgp confederation identifier as-number
no bgp confederation identifier [as-number]
Syntax Description
as-number
Autonomous system (AS) number that internally includes multiple autonomous systems. Range for 2-byte numbers is 1 to 65535. Range for 4-byte numbers is 1.0 to 65535.65535.
Defaults
No confederation identifier is configured.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
One way to reduce the internal BGP (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. Although the peers in different autonomous systems have external BGP (eBGP) sessions, they exchange routing information as if they are iBGP peers. Specifically, the confederation maintains the next hop and local preference information, and that allows you to retain a single Interior Gateway Protocol (IGP) for all autonomous systems. To the outside world, the confederation looks like a single autonomous system.
Use the bgp confederation identifier command to specify the autonomous system number for the confederation. This autonomous system number is used when BGP sessions are established with external peers in autonomous systems that are not part of the confederation.
Task ID
Examples
The following example shows how to divide the autonomous system into autonomous systems 4001, 4002, 4003, 4004, 4005, 4006, and 4007 with the confederation identifier 5. Neighbor 10.2.3.4 is a router inside the confederation. Neighbor 172.20.16.6 is outside the routing domain confederation. To the outside world, there appears to be a single autonomous system with the number 5.
RP/0/RP0/CPU0:router(config)# router bgp 4001RP/0/RP0/CPU0:router(config-bgp)# bgp confederation identifier 5RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4002RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4003RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4004RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4005RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4006RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4007RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.2.3.4RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 4002RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# exitRP/0/RP0/CPU0:router(config-bgp-nbr)# neighbor 172.20.16.6RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 4009Related Commands
bgp confederation peers
To configure the autonomous systems that belong to the confederation, use the bgp confederation peers command in an appropriate configuration mode. To remove the autonomous system from the confederation, use the no form of this command.
bgp confederation peers [as-number]
no bgp confederation peers [as-number]
Syntax Description
Defaults
No BGP peers are identified as belonging to the confederation.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
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.
To specify multiple autonomous systems, enter BGP confederation peer configuration mode then enter one autonomous-system-number for each command line. The following example shows how to configure multiple autonomous systems in BGP confederation peer configuration mode:
router bgp 101bgp confederation peers567645756Task ID
Examples
The following example shows that autonomous systems 1090 and 1093 belong to a single confederation:
RP/0/RP0/CPU0:router(config)# router bgp 1090RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 1093The following example shows that autonomous systems 1095, 1096, 1097, and 1098 belong to a single confederation:
RP/0/RP0/CPU0:router(config)# router bgp 1095RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peersRP/0/RP0/CPU0:router(config-bgp-confed-peers)# 1096RP/0/RP0/CPU0:router(config-bgp-confed-peers)# 1097RP/0/RP0/CPU0:router(config-bgp-confed-peers)# 1098Related Commands
bgp dampening
To enable Border Gateway Protocol (BGP) route dampening or change various BGP route dampening factors, use the bgp dampening command in an appropriate configuration mode. To disable route dampening and reset default values, use the no form of this command.
bgp dampening [half-life [reuse suppress max-suppress-time] | route-policy route-policy-name]
no bgp dampening [half-life [reuse suppress max-suppress-time] | route-policy route-policy-name]
Syntax Description
Defaults
Route dampening is disabled.
half-life: 15 minutes
reuse: 750
suppress: 2000
max-suppress-time: four times half-life valueCommand Modes
IPv4 address family configuration
IPv6 address family configuration
VPNv4 address family configuration
VRF IPv4 address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp dampening command without arguments to enable BGP route dampening with the default parameters. The parameters can be changed by setting them on the command line or specifying them with a routing policy.
Task ID
Examples
The following example shows how to set the half-life value to 30 minutes, the reuse value to 1500, the suppress value to 10000, and the max-suppress-time to 120 minutes:
RP/0/RP0/CPU0:router(config)# router bgp 50RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp dampening 30 1500 10000 120Related Commands
bgp default local-preference
To change the default local preference value, use the bgp default local-preference command in an appropriate configuration mode. To reset the local preference value to the default of 100, use the no form of this command.
bgp default local-preference value
no bgp default local-preference [value]
Syntax Description
Defaults
Enabled with a value of 100.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
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 networking devices in the local autonomous system.
Task ID
Examples
The following example shows how to raise the default local preference value from the default of 100 to 200:
RP/0/RP0/CPU0:router(config)# router bgp 200RP/0/RP0/CPU0:router(config-bgp)# bgp default local-preference 200bgp enforce-first-as disable
To disable the software from enforcing the first autonomous system path (known as the AS path) of a route received from an external Border Gateway Protocol (eBGP) peer to be the same as the configured remote autonomous system, use the bgp enforce-first-as disable command in an appropriate configuration mode. To re-enable enforcing the first AS path of a received route from an eBGP peer to be the same as the remote autonomous system, use the no form of this command.
bgp enforce-first-as disable
no bgp enforce-first-as disable
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the software requires the first autonomous system (in the AS path) of a route received from an eBGP peer to be the same as the remote autonomous system configured.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, the software ignores any update received from an eBGP neighbor that does not have the autonomous system configured for that neighbor at the beginning of the AS path. When configured, the command applies to all eBGP peers of the router.
Task ID
Examples
The following example shows a configuration in which incoming updates from eBGP neighbors are not checked to ensure the first AS number in the AS path is the same as the configured AS number for the neighbor:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp enforce-first-as disableRelated Commands
bgp fast-external-fallover disable
To disable immediately resetting the Border Gateway Protocol (BGP) sessions of any directly adjacent external peers if the link used to reach them goes down, use the bgp fast-external-fallover disable command in an appropriate configuration mode. To disable this function and perform an immediate reset of BGP sessions when a link between peers is lost, use the no form of this command.
bgp fast-external-fallover disable
no bgp fast-external-fallover disable
Syntax Description
Defaults
BGP sessions of any directly adjacent external peers are immediately reset if the link used to reach them goes down.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, BGP sessions of any directly adjacent external peers are immediately reset, which allows the network to recover faster when links go down between BGP peers.
Task ID
Examples
The following example shows how to disable the automatic resetting of BGP sessions:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# bgp fast-external-fallover disablebgp graceful-restart
To enable graceful restart support, use the bgp graceful-restart command in an appropriate configuration mode. To disable this function, use the no form of this command.
bgp graceful-restart
no bgp graceful-restart
Syntax Description
This command has no arguments or keywords.
Defaults
Graceful restart support is not enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp graceful-restart command to enable graceful restart functionality on the router, and also to advertise graceful restart to neighboring routers.
Note
When graceful restart is enabled, the BGP graceful restart capability is negotiated with neighbors in the BGP OPEN message when the session is established. If the neighbor also advertises support for graceful restart, then graceful restart is activated for that neighbor session. If the neighbor does not advertise support for graceful restart, then graceful restart is not activated for that neighbor session even though it is enabled locally.
If you enter the bgp graceful-restart command after some BGP sessions are established, you must restart those sessions before graceful restart takes effect. Use the clear bgp command to restart sessions.
Task ID
Examples
The following example shows how to enable graceful restart:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restartRelated Commands
bgp graceful-restart graceful-reset
To invoke a graceful restart when configuration changes force a peer reset, use the bgp graceful-restart graceful-reset command in an appropriate configuration mode. To disable this function, use the no form of this command.
bgp graceful-restart graceful-reset
no bgp graceful-restart graceful-reset
Syntax Description
This command has no arguments or keywords.
Defaults
Graceful restart is not invoked when a configuration change forces a peer reset.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before enabling graceful reset using the bgp graceful-restart graceful-reset command.
Task ID
Examples
The following example shows how to enable graceful reset:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart graceful-resetRelated Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart purge-time
To specify the maximum time before stale routes are purged from the routing information base (RIB) when the local BGP process restarts, use the bgp graceful-restart purge-time command in an appropriate configuration mode. To set the purge timer time to its default value, use the no form of this command.
bgp graceful-restart purge-time seconds
no bgp graceful-restart purge-time seconds
Syntax Description
Defaults
seconds: 600
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before setting the purge time using the bgp graceful-restart purge-time command.
Task ID
Examples
The following example shows how to change the BGP purge time to 800 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart purge-time 800Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart restart-time
To specify a user-predicted local BGP process maximum restart time, which is advertised to neighbors during session establishment, use the bgp graceful-restart restart-time command in an appropriate configuration mode. To set this restart time to its default value, use the no form of this command.
bgp graceful-restart restart-time seconds
no bgp graceful-restart restart-time seconds
Syntax Description
Defaults
seconds: 120
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before setting the restart timer using the bgp graceful-restart restart-time command.
Task ID
Examples
The following example shows how to change the BGP graceful restart time to 400 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart restart-time 400Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart stalepath-time
To specify the maximum time to wait for an End-of-RIB message after a neighbor restarts, use the bgp graceful-restart stalepath-time command in an appropriate configuration mode. To set the stalepath timer time to its default value, use the no form of this command.
bgp graceful-restart stalepath-time seconds
no bgp graceful-restart stalepath-time seconds
Syntax Description
Defaults
seconds: 360
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before setting the stalepath time using the bgp graceful-restart stalepath-time command.
If the stalepath time is exceeded before an End-of-RIB message is received from a neighbor, paths learned from the neighbor are purged from the BGP routing table.
Task ID
Examples
The following example shows how to change the stalepath time to 750 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart stalepath-time 750Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp log neighbor changes disable
To disable logging of Border Gateway Protocol (BGP) neighbor resets, use the bgp log neighbor changes disable command in an appropriate configuration mode. To re-enable logging of BGP neighbor resets, use the no form of this command.
bgp log neighbor changes disable
no bgp log neighbor changes disable
Syntax Description
This command has no arguments or keywords.
Defaults
BGP neighbor changes are logged.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Logging of BGP neighbor status changes (up or down) and resets is used for troubleshooting network connectivity problems and measuring network stability. Unexpected neighbor resets might indicate high error rates or high packet loss in the network, and should be investigated.
Status change message logging does not substantially affect performance, unlike, for example, enabling per-BGP update debugging. If the UNIX syslog facility is enabled, messages are sent by the software to the UNIX host running the syslog daemon so that the messages can be stored and archived on disk. If the UNIX syslog facility is not enabled, the status change messages are kept in the internal buffer of the router, and are not stored to disk. You can set the size of this buffer, which is dependent upon the available RAM, using the logging buffered command.
The neighbor status change messages are not tracked if the bgp log neighbor changes disabled command is disabled, except for the last reset reason, which is always available as output of the show bgp neighbors command.
Up and down messages for BGP neighbors are logged by the software by default. Use the bgp log neighbor changes disable command to stop logging BGP neighbor changes.
Use the show logging command to display the log for the BGP neighbor changes.
Task ID
Examples
The following example shows how to prevent the logging of neighbor changes for BGP:
RP/0/RP0/CPU0:router(config)# router bgp 65530RP/0/RP0/CPU0:router(config-bgp)# bgp log neighbor change disableRelated Commands
logging buffered
Logs messages to an internal buffer.
Displays information about the TCP and BGP connections to neighbors.
show logging
Displays the state of logging (syslog).
bgp maximum neighbor
To control the maximum number of neighbors that can be configured on the router, use the bgp maximum neighbor command in an appropriate configuration mode. To set the neighbor limit to the default value, use the no form of this command.
bgp maximum neighbor limit
no maximum neighbor [limit]
Syntax Description
Defaults
Default limit is 4000
Command Modes
Router configuration
Command History
Release 3.2
This command was first supported on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.3.0
No modification.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Any attempt to configure the neighbor limit below 1 or above 1500 fails. Similarly, attempting to configure the limit below the number of neighbors currently configured fails. For example, if there are 3250 neighbors configured, you cannot set the limit below 3250.
Task ID
Examples
The following example shows how to change the default maximum neighbor limit and set it to 1200:
RP/0/RP0/CPU0:router(config)# router bgp 65530RP/0/RP0/CPU0:router(config-bgp)# bgp maximum neighbor 1200bgp redistribute-internal
To allow the redistribution of internal Border Gateway Protocol (iBGP) routes into an Interior Gateway Protocol (IGP), such as Intermediate System-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF), use the bgp redistribute-internal command in an appropriate configuration mode. To disable the redistribution of iBGP routes into IGPs, use the no form of this command.
bgp redistribute-internal
no bgp redistribute-internal
Syntax Description
This command has no arguments or keywords.
Defaults
By default, iBGP routes are not redistributed into IGPs.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use of the bgp redistribute-internal command requires the clear route * command to be issued to reinstall all BGP routes into the IP routing table.
Note
Task ID
Examples
The following example shows how to redistribute iBGP routes into OSPF:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# bgp redistribute-internalRP/0/RP0/CPU0:router(config-bgp)# exitRP/0/RP0/CPU0:router(config)# router ospf area1RP/0/RP0/CPU0:router(config-router)# redistribute bgp 1RP/0/RP0/CPU0:router(config-router)# endRP/0/RP0/CPU0:router# clear route *Related Commands
bgp router-id
To configure a fixed router ID for a Border Gateway Protocol (BGP)-speaking router, use the bgp router-id command in an appropriate configuration mode. To disable a fixed router ID, use the no form of this command.
bgp router-id ip-address
no bgp router-id [ip-address]
Syntax Description
ip-address
IP Version 4 (IPv4) address to use as the router ID. Normally, this should be an IPv4 address assigned to the router.
Defaults
If no router ID is configured in BGP, BGP attempts to use the global router ID if one is configured and available. Otherwise, BGP uses the highest IP address configured on a loopback interface.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If you do not use the bgp router-id command to configure a router ID, an IP address is not configured on any loopback interface, and no global router ID is configured, BGP neighbors remain down.
For more details on router IDs, see Cisco IOX XR Routing Configuration Guide.
Task ID
Examples
The following example shows how to configure the local router with the router ID of 192.168.70.24:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp router-id 192.168.70.24Related Commands
bgp scan-time
To configure scanning intervals of Border Gateway Protocol (BGP)-speaking networking devices, use the bgp scan-time command in an appropriate configuration mode and address family configuration mode. To restore the scanning interval to its default value, use the no form of this command.
bgp scan-time seconds
no bgp scan-time [seconds]
Syntax Description
Defaults
The default scanning interval is 60 seconds.
Command Modes
Router configuration
IPv4 address family configuration
IPv6 address family configuration
VPNv4 address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp scan-time command to change how frequently the software processes scanner tasks, such as conditional advertisement, dynamic MED changes, and periodic maintenance tasks.
Task ID
Examples
The following example shows how to set the scanning interval for IPv4 unicast to 20 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 64500RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp scan-time 20Related Commands
bgp update-delay
To set the maximum initial delay for a Border Gateway Protocol (BGP)-speaking router to send the first updates, use the bgp update-delay command in an appropriate configuration mode. To restore the initial delay to its default value, use the no form of this command.
bgp update-delay seconds [always]
no bgp update-delay [seconds] [always]
Syntax Description
Defaults
120 seconds
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
When BGP is started, it waits a specified period of time for its neighbors to establish peering sessions and to complete sending their initial updates. After all neighbors complete their initial updates, or after the update delay timer expires, the best path is calculated for each route, and the software starts sending advertisements out to its peers. This behavior improves convergence time. If the software were to advertise a route as soon as it learned it, it would have to readvertise the route each time it learned a new path that was preferred over all previously learned paths.
Use the bgp update-delay command to tune the maximum time the software waits after the first neighbor is established until it starts calculating best paths and sending out advertisements.
Task ID
Examples
The following example shows how to set the maximum initial delay to 240 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 64530RP/0/RP0/CPU0:router(config-bgp)# bgp update-delay 240bgp write-limit
To modify the upper bounds on update message queue lengths or to enable desynchronization, use the bgp write-limit command in an appropriate configuration mode. To return the bounds to their default values and to disable desynchronization, use the no form of this command.
bgp write-limit group-limit global-limit [desynchronize]
no bgp write-limit [group-limit global-limit] [desynchronize]
Syntax Description
Defaults
group-limit: 50,000
global-limit: 250,000
Desynchronization is off.Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp write-limit command to configure both a per-update group and a global limit on the number of messages the software queues when updating peers. Increasing these limits can result in faster Border Gateway Protocol (BGP) convergence, but also may result in higher memory use during convergence. In addition, this command can be used to enable desynchronization. Desynchronization can decrease memory use and speed up convergence for the fastest neighbors if one or more neighbors in an update group process updates significantly slower than other neighbors in the same group. However, enabling desynchronization can cause a significant degradation in overall convergence time, especially if the router is experiencing high CPU utilization. For this reason, enabling desynchronization is discouraged.
Task ID
Examples
The following example shows how to configure BGP to operate with a per-update group limit of 9000 messages and a global limit of 27,000 messages:
RP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# bgp write-limit 9000 27000capability orf prefix
To advertise prefix list-based Outbound Route Filter (ORF) capability to the Border Gateway Protocol (BGP) peer, use the capability orf prefix command in an appropriate configuration mode. To remove the capability orf prefix command from the configuration file and restore the system to its default condition in which the software does not advertise the capability, use the no form of this command.
capability orf prefix {receive | send | both | none}
no capability orf prefix [receive | send | both | none]
Syntax Description
Defaults
The routing device does not receive or send route prefix filter lists.
Command Modes
IPv4 address family group configuration
IPv6 address family group configuration
IPv4 neighbor address family configuration
VRF neighbor IPv4 address family configuration
IPv4 neighbor group address family configuration
IPv6 neighbor group address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The advertisement of the prefix list ORF capability by a BGP speaker indicates whether the speaker can send prefix lists to the specified neighbor and whether it accepts prefix lists from the neighbor. The speaker sends a prefix list if it indicated the ability to send them, and if the neighbor indicated it was willing to accept them. Similarly, the neighbor sends a prefix list to the speaker if it indicated the ability to send them and the speaker indicated the willingness to accept them.
Note
If the neighbor sends a prefix list and the speaker accepts it, the speaker applies the received prefix list, plus any locally configured outbound filters, to limit its outbound routing updates to the neighbor. Increased filtering prevents unwanted routing updates between neighbors and reduces resource requirements for routing update generation and processing.
Use the capability orf prefix command to set whether to advertise send and receive capabilities to the specified neighbor.
Note
If this command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Task ID
Examples
The following example shows how to configure the capability orf prefix command:
RP/0/RP0/CPU0:# configureRP/0/RP0/CPU0:(config)# route-policy orfqqRP/0/RP0/CPU0:(config-rpl)# if orf prefix in (10.0.0.0/8 ge 20) thenRP/0/RP0/CPU0:(config-rpl)# passRP/0/RP0/CPU0:(config-rpl)# endifRP/0/RP0/CPU0:(config-rpl)# if orf prefix in (1910::16 ge 120) thenRP/0/RP0/CPU0:(config-rpl)# passRP/0/RP0/CPU0:(config-rpl)# endifRP/0/RP0/CPU0:(config-rpl)# end-policyRP/0/RP0/CPU0:(config)# router bgp 65530RP/0/RP0/CPU0:(config-bgp)# neighbor 10.0.101.1RP/0/RP0/CPU0:(config-bgp-nbr)# remote-as 65534RP/0/RP0/CPU0:(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:(config-bgp-nbr-af)# route-policy pass-all outRP/0/RP0/CPU0:(config-bgp-nbr-af)# capability orf prefix bothRP/0/RP0/CPU0:(config-bgp-nbr-af)# orf route-policy orfqqRelated Commands
clear bgp
To reset a group of Border Gateway Protocol (BGP) neighbors, use the clear bgp command in EXEC mode.
clear bgp [ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}] {* soft | ip-address | external | as as-number} [graceful]
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp command to reset the sessions of the specified group of neighbors (hard reset); it removes the TCP connection to the neighbor, removes all routes received from the neighbor from the BGP table, and then re-establishes the session with the neighbor.
If the graceful keyword is specified, the routes from the neighbor are not removed from the BGP table immediately, but are marked as stale. After the session is re-established, any stale route that has not been received again from the neighbor is removed.
Task ID
Examples
The following example shows how to hard reset neighbor 10.0.0.1:
RP/0/RP0/CPU0:router# clear bgp 10.0.0.1The following example shows how to hard reset all neighbors with a graceful restart:
RP/0/RP0/CPU0:router# clear bgp * gracefulRelated Commands
clear bgp current-mode
To switch from one BGP mode to another, use the clear bgp current-mode command in EXEC mode.
clear bgp current-mode
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp current-mode command to switch from standalone to distributed mode, or from distributed to standalone mode. The show bgp process command indicates the current BGP mode.
Note
Task ID
Examples
The following example shows the show bgp process command output before and after switching from one BGP mode to another:
RP/0/RP0/CPU0:router# show bgp process
BGP Process InformationBGP is operating in STANDALONE modeAutonomous System: 3Router ID: 10.18.18.11Cluster ID: 10.18.18.11Fast external fallover enabledNeighbor logging is enabledEnforce first AS enabledDefault local preference: 100Default keepalive: 60Update delay: 120Generic scan interval: 60Address family: IPv4 UnicastDampening is not enabledClient reflection is enabledScan interval: 60Main Table Version: 3IGP notification: IGPs notifiedRIB has converged: version 0Node Process Nbrs Estb Rst Upd-Rcvd Upd-Sent Nfn-Rcv Nfn-Sntnode0_0_CPU0 Speaker 5 5 51 0 7 0 5RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# distributed speaker 1RP/0/RP0/CPU0:router(config-bgp)# distributed speaker 2RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.101.1RP/0/RP0/CPU0:router(config-bgp-nbr)# speaker-id 2RP/0/RP0/CPU0:router(config-bgp-nbr)# commitRP/0/RP0/CPU0:router# clear bgp current-modeRP/0/RP0/CPU0:router# show bgp processBGP Process InformationBGP is operating in DISTRIBUTED modeAutonomous System: 3Router ID: 10.18.18.11Cluster ID: 10.18.18.11Fast external fallover enabledNeighbor logging is enabledEnforce first AS enabledDefault local preference: 100Default keepalive: 60Update delay: 120Generic scan interval: 60Address family: IPv4 UnicastDampening is not enabledClient reflection is enabledScan interval: 60Main Table Version: 1IGP notification: IGPs not notifiedRIB has not converged: version 0Node Process Nbrs Estb Rst Upd-Rcvd Upd-Sent Nfn-Rcv Nfn-Sntnode0_0_CPU0 Speaker 1 4 1 52 0 0 0 4node0_0_CPU0 Speaker 2 1 0 9 0 0 0 1node0_0_CPU0 bRIB 1 0 0 0 0 0 0 0node0_0_CPU0 bRIB 2 0 0 0 0 0 0 0Related Commands
clear bgp dampening
To clear Border Gateway Protocol (BGP) route dampening information and unsuppress the suppressed routes, use the clear bgp dampening command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} dampening [ip-address/mask-length]
Syntax Description
Defaults
If no IP address is specified, dampening information for all routes is cleared.
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear the route dampening information for all 172.20.0.0/16 IPv4 multicast paths:
RP/0/RP0/CPU0:router# clear bgp ipv4 multicast dampening 172.20.0.0/16Related Commands
Enables BGP route dampening or changes various BGP route dampening factors.
Displays BGP dampened routes.
clear bgp flap-statistics
To clear Border Gateway Protocol (BGP) flap counts for a specified group of routes, use the clear bgp flap-statistics command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} flap-statistics [regexp regexp | route-policy route-policy-name | network/mask-length | ip-address]
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear the flap count for all routes (in all address families) originating in autonomous system 1:
RP/0/RP0/CPU0:router# clear bgp all all flap-statistics regexp _1$The following example shows how to clear the flap count for all IPv4 unicast routes received from neighbor 172.20.1.1:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics 172.20.1.1clear bgp nexthop performance-statistics
To reset the number of received notifications and the cumulative processing time for the Border Gateway Protocol (BGP) next hop, use the clear bgp nexthop performance-statistics command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} nexthop performance-statistics
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Release 3.4.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp nexthop performance-statistics command to reset the total number of notifications received from the Routing Information Base (RIB) and the cumulative next-hop processing time. The following information is cleared from the show bgp nexthops command output:
•
•
•
•
•
Task ID
Examples
The following example shows how to clear next-hop performance statistics:
RP/0/RP0/CPU0:router# clear bgp vrf vrf_A nexthop performance statisticsRelated Commands
clear bgp nexthop registration
To reregister a specified next hop with the Routing Information Base (RIB), use the clear bgp nexthop registration command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} nexthop registration nexthop-address
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Release 3.4.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp nexthop registration command to perform an asynchronous registration of the next hop with the RIB. The show bgp nexthops command output shows a critical notification as the LastRIBEvent for the next hop when the clear bgp nexthop registration command is used.
Task ID
Examples
The following example shows how to reregister the next hop with the RIB:
RP/0/RP0/CPU0:router# clear bgp nexthop registration 10.1.1.1Related Commands
clear bgp peer-drops
To clear the connection-dropped counter, use the clear bgp peer-drops command in EXEC mode.
clear bgp peer-drops {* | ip-address}
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear the connection-dropped counter for all BGP neighbors:
RP/0/RP0/CPU0:router# clear bgp peer-drops *Related Commands
clear bgp performance-statistics
To clear the performance statistics for all address families, use the clear bgp performance-statistics command.
clear bgp performance-statistics
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear the performance statistics for all address families:
RP/0/RP0/CPU0:router# clear bgp performance-statisticsclear bgp self-originated
To clear Border Gateway Protocol (BGP) routes that are self-originated, use the clear bgp self-originated command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} self-originated
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Self-originated routes are routes locally originated by the network command, redistribute command, or aggregate-address command.
Task ID
Examples
The following example shows how to clear self-originated IPv4 routes:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast self-originatedRelated Commands
clear bgp shutdown
To clear all Border Gateway Protocol (BGP) neighbors that shut down due to low memory, use the clear bgp shutdown command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}} shutdown
Syntax Description
Defaults
No default behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear all shut-down BGP neighbors:
RP/0/RP0/CPU0:router# clear bgp shutdownRelated Commands
Displays entries in the BGP routing table.
Displays information about the TCP and BGP connections to neighbors.
clear bgp soft
To soft reset a group of Border Gateway Protocol (BGP) neighbors, use the clear bgp soft command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | labeled-unicast | all} | ipv6 {unicast | multicast | all} | all {unicast | multicast | all} | vpnv4 unicast | vrf {vrf-name | all} {ipv4 {unicast | labeled-unicast}}} {* | ip-address | as-number | external} soft [in [prefix-filter] | out]
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp soft command to trigger a soft reset of the specified address families for the specified group of neighbors. This command is useful if you change the inbound or outbound policy for the neighbors, or any other configuration that affects the sending or receiving of routing updates.
If an outbound soft reset is triggered, BGP resends all routes for the address family to the given neighbors.
If an inbound soft reset is triggered, BGP by default sends a REFRESH request to the neighbor, if the neighbor has advertised the ROUTE_REFRESH capability. To determine whether the neighbor has advertised the ROUTE_REFRESH capability, use the show bgp neighbors command, and look for the following line of output:
Received route refresh capability from peer.If the neighbor does not support route refresh, but the soft-reconfiguration inbound command is configured for the neighbor, then BGP uses the routes cached as a result of the soft-reconfiguration inbound command to perform the soft reset.
If you want BGP to use the cached routes even if the neighbor supports route refresh, you can use the always keyword when configuring the soft-reconfiguration inbound command.
If the neighbor does not support route refresh and the soft-reconfiguration inbound command is not configured, then inbound soft reset is not possible. In this case, an error is printed.
Note
Task ID
Examples
The following example shows how to trigger an inbound soft clear for IPv4 unicast routes received from neighbor 10.0.0.1:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast 10.0.0.1 soft inRelated Commands
default-information originate (BGP)
To allow origination of a default route to be redistributed into the Border Gateway Protocol (BGP) from another protocol, use the default-information originate command in an appropriate configuration mode. To disable this function, use the no form of this command.
default-information originate
no default-information originate
Syntax Description
This command has no arguments or keywords.
Defaults
BGP does not permit redistribution of a default route into BGP.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the redistribute command to redistribute routes from another protocol into BGP. By default, if these routes include the default route (0.0.0.0/0 for IPv4 or ::/0 for IPv6), the default route is ignored. Use the default-information originate command to change this behavior so that the default route is not ignored and is redistributed into BGP along with the other routes for the protocol being redistributed.
Task ID
Examples
The following example shows how to configure BGP to redistribute the default route into BGP:
RP/0/RP0/CPU0:router(config)# router bgp 164RP/0/RP0/CPU0:router(config-bgp)# default-information originateRelated Commands
default-metric (BGP)
To set default metric values for the Border Gateway Protocol (BGP), use the default-metric command in an appropriate configuration mode. To disable metric values, use the no form of this command.
default-metric value
no default-metric [value]
Syntax Description
value
Default metric value appropriate for the specified routing protocol. Range is 1 to 4294967295.
Defaults
A metric is not sent.
Command Modes
Router configuration
VRF configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the default-metric command to set the Multi Exit Discriminator (MED) to advertise to peers for routes that do not already have a metric set (routes that were received with no MED attribute).
Task ID
Examples
The following example shows how to set the BGP default metric:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# default-metric 10default-originate
To cause a Border Gateway Protocol (BGP) speaker (the local router) to send the default route 0.0.0.0/0 to a neighbor for use as a default route, use the default-originate command in an appropriate configuration mode. To disable this function, use the no form of this command.
default-originate [disable | route-policy route-policy-name]
no default-originate [disable | route-policy route-policy-name]
Syntax Description
Defaults
The default route is not advertised to BGP neighbors.
Command Modes
IPv4 neighbor address family configuration
IPv4 neighbor group address family configuration
IPv6 neighbor group address family configuration
IPv4 address family group configuration
IPv6 address family group configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The default-originate command does not require the presence of the default route (0.0.0.0/0 for IPv4 or ::/0 for IPv6) in the local router. When the default-originate command is used with a route policy, the default route is advertised if any route in the BGP table matches the policy.
Task ID
Examples
The following example shows how to unconditionally advertise the route 0.0.0.0/0 to the neighbor 172.20.2.3:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.2.3RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 200RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# default-originateThe following example shows how to advertise the route 0.0.0.0/0 to the neighbor 172.20.2.3 only if a route exists in the BGP table that matches the route policy called default-default-policy:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.2.3RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 200RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# default-originate route-policy default-default-policyRelated Commands
description (BGP)
To annotate a neighbor, neighbor group, VPN routing and forwarding (VRF) neighbor, or session group, use the description command in an appropriate configuration mode. To remove the annotation, use the no form of this command.
description text
no description [text]
Syntax Description
Defaults
No comment or description exists.
Command Modes
Neighbor group configuration
Neighbor configuration
Session group configuration
VRF neighbor configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the description command to provide a description of a neighbor, neighbor group, VRF neighbor, or session group. The description is used to save user comments and does not affect software function.
Task ID
Examples
The following example shows how to configure the description "Our best customer" on the neighbor 192.168.13.4:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.13.4RP/0/RP0/CPU0:router(config-bgp-nbr)# description Our best customerdistance bgp
To allow the use of external, internal, and local administrative distances that could be used to prefer one class of routes over another, use the distance bgp command in an appropriate configuration mode. To disable the use of administrative distances, use the no form of this command.
distance bgp external-distance internal-distance local-distance
no distance bgp [external-distance internal-distance local-distance}
Syntax Description
Defaults
external-distance: 20
internal-distance: 200
local-distance: 200Command Modes
IPv4 address family configuration
IPv6 address family configuration
VRF IPv4 address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the distance bgp command if another protocol is known to be able to provide a better route to a node than was actually learned using external BGP, or if some internal routes should be preferred by BGP.
Note
An administrative distance is a rating of the trustworthiness of a routing information source. Numerically, an administrative distance is an integer from 1 to 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.
Task ID
Examples
The following example shows that iBGP routes are preferable to locally generated routes, so the administrative distance values are set accordingly:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# distance bgp 20 20 200Related Commands
distributed speaker
To enable a distributed speaker process, use the distributed speaker command in router configuration mode. To remove the distributed speaker process, use the no form of this command.
distributed speaker id
no distributed speaker id
Syntax Description
Defaults
Default is 0.
Command Modes
Router configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If BGP is currently running in standalone mode, you must enter the clear bgp current-mode or clear bgp vrf all * command to switch from standalone or distributed mode.
Task ID
Examples
The following example shows how to enable distributed speaker process 3:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# distributed speaker 3Related Commands
Switches BGP from one mode to another.
clear bgp vrf all *
Resets the BGP VPN routing and forwarding (VRF) neighbor.
dmz-link-bandwidth
To originate a demilitarized zone (DMZ) link bandwidth extended community for the link to an eBGP neighbor, use the dmz-link-bw command in an appropriate configuration mode. To cease origination of the DMZ link bandwidth extended community, use the no form of this command.
dmz-link-bandwidth [disable]
no dmz-link-bandwidth [disable]
Syntax Description
disable
(Optional) Prevents the dmz-link-bandwidth command from being inherited from a parent group.
Defaults
BGP does not originate the DMZ link bandwidth extended community.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configuration
VRF neighbor configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the dmz-link-bandwidth command to advertise the bandwidth of links that are used to exit an autonomous system.
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Task ID
Examples
The following example shows how to advertise the bandwidth of links to eBGP neighbors from router bgp 1:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 45.67.89.01RP/0/RP0/CPU0:router(config-bgp-nbr)# dmz-link-bandwidthRelated Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
dscp (BGP)
To set the differentiated services code point (DSCP) value, use the dscp command in the appropriate configuration mode. To remove the dscp command from the configuration file and restore the system to its default interval values, use the no form of this command.
dscp value
no dscp [value]
Syntax Description
Defaults
No default behavior or values
Command Modes
Neighbor configuration
Neighbor session group configuration
Neighbor group configurationCommand History
Release 3.4.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the dscp command to change the minimum and maximum packet thresholds for the DSCP value.
Table 2 lists the DSCP default settings used by the dscp command. The DSCP value, corresponding minimum threshold, maximum threshold, and mark probability are listed. The last row of the table (the row labeled "default") shows the default settings used for any DSCP value not specifically shown in the table.
Task ID
Examples
The following example shows how to set the DSCP value to af32:
RP/0/RP0/CPU0:router(config)# router bgp 5RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.1.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 100RP/0/RP0/CPU0:router(config-bgp-nbr)# dscp af32ebgp-multihop
To accept and attempt Border Gateway Protocol (BGP) connections to external peers residing on networks that are not directly connected, use the ebgp-multihop command in an appropriate configuration mode. To disable connections to external peers and allow only direct connections between neighbors, use the no form of this command.
ebgp-multihop [ttl-value]
no ebgp-multihop [ttl-value]
Syntax Description
Defaults
Default TTL value is 255.
Command Modes
Neighbor configuration
VRF neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the ebgp-multihop command to enable multihop peerings with external BGP neighbors. The BGP protocol states that external neighbors must be directly connected (one hop away). The software enforces this by default; however, the ebgp-multihop command can be used to override this behavior.
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Task ID
Examples
The following example shows how to allow a BGP connection to neighbor 172.20.16.6 of up to 255 hops away:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.16.6RP/0/RP0/CPU0:router(config-bgp-nbr)# ebgp-multihopRelated Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
export route-policy
To configure an export route policy, use the export route-policy command in global VRF IPV4 address family configuration mode. To restore the system to its default condition, use the no form of this command.
export route-policy policy-name
no export route-policy [policy-name]
Syntax Description
Defaults
No default behavior or values
Command Modes
Global VRF IPv4 address family configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the export route-policy command to define the conditions that allow specified routes to be tagged with specified route-targets.
Task ID
Examples
The following example shows how to configure an export route policy:
RP/0/RP0/CPU0:router(config)# vrf vrf-1RP/0/RP0/CPU0:router(config-vrf)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-vrf-af)# export route-policy policy-ARelated Commands
export route-target
To configure a VPN routing and forwarding (VRF) export route-target extended community, use the export route-target command in global VRF IPv4 address family configuration mode. To restore the system to its default condition, use the no form of this command.
export route-target [as-number:nn | ip-address:nn]
no export route-target [as-number:nn | ip-address:nn]
Syntax Description
Defaults
No default behavior or values
Command Modes
Global VRF IPv4 address family configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Export route-target extended communities are associated with prefixes when advertised to remote provider edge (PE) routers. The remote PE routers import the route-target extended communities into a VRF instance that has the import route-targets that match the exported route-target extended communities.
Task ID
Examples
The following example shows how to specify an export route-target:
RP/0/RP0/CPU0:router(config)# vrf vrf-1RP/0/RP0/CPU0:router(config-vrf)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-vrf-af)# export route-target 500:1Related Commands
import route-policy
To configure an import route policy, use the import route-policy command in global VRF IPv4 address family configuration mode. To restore the system to its default condition, use the no form of this command.
import route-policy policy-name
no import route-policy [policy-name]
Syntax Description
Defaults
No default behavior or values
Command Modes
Global VRF IPv4 address family configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the import route-policy command to define the conditions that allow specified routes to be imported into the VPN routing and forwarding (VRF) instance if the routes are tagged with specified route-targets.
Task ID
Examples
The following example shows how to allow only policy-B to be imported to VRF:
RP/0/RP0/CPU0:router(config)# vrf vrf-1RP/0/RP0/CPU0:router(config-vrf)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-vrf-af)# import route-policy policy-BRelated Commands
import route-target
To configure a VPN routing and forwarding (VRF) import route-target extended community, use the import route-target command in global VRF IPv4 address family configuration mode. To restore the system to its default condition, use the no form of this command.
import route-target [as-number:nn | ip-address:nn]
no import route-target [as-number:nn | ip-address:nn]
Syntax Description
Defaults
No default behavior or values
Command Modes
Global VRF IPv4 address family configuration
Command History
Release 3.3.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Release 3.4.0
No modification.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the import route-target command to specify that prefixes associated with the configured import route-target extended communities are imported into the VPN routing and forwarding (VRF) instance.
Task ID
Examples
The following example shows how to specify an import route-target:
RP/0/RP0/CPU0:router(config)# vrf vrf-1RP/0/RP0/CPU0:router(config-vrf)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-vrf-af)# import route-target 500:99Related Commands
keychain
To apply key chain-based authentication on a TCP connection between two Border Gateway Protocol (BGP) neighbors, use the keychain command in an appropriate configuration mode. To disable key chain authentication, use the no form of this command.
keychain name
no keychain [name]
Syntax Descriptionr
name
Key chain name configured using the keychain command. The name must be a maximum of 32 alphanumeric characters.
Defaults
When this command is not specified in the appropriate configuration mode, key chain authentication is not enabled on a TCP connection between two BGP neighbors.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 3.4.0
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Specify a key chain to enable key chain authentication between two BGP peers. Use
