-
Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2
-
About Cisco IOS Software Documentation
-
Using Cisco IOS Software
-
On-Demand Routing Commands
-
RIP Commands
-
IGRP Commands
-
OSPF commands
-
EIGRP Commands
-
Integrated IS-IS Commands
- Part 1: BGP Commands
-
Multiprotocol BGP Extensions for IP Multicast Commands
- Part 2: IP Routing Protocol-Independent Commands
-
Index - 12.2 - IP Routing Protocols Command Reference
-
Table Of Contents
neighbor peer-group (creating)
neighbor route-reflector-client
network (BGP and multiprotocol BGP)
neighbor peer-group (creating)
To create a BGP or multiprotocol BGP peer group, use the neighbor peer-group command in address family or router configuration mode. To remove the peer group and all of its members, use the no form of this command.
neighbor peer-group-name peer-group
no neighbor peer-group-name peer-group
Syntax Description
Defaults
There is no BGP peer group.
Command Modes
Address family configuration
Router configuration
Command History
Usage Guidelines
Often in a BGP or multiprotocol BGP speaker, many neighbors are configured with the same update policies (that is, same outbound route maps, distribute lists, filter lists, update source, and so on). Neighbors with the same update policies can be grouped into peer groups to simplify configuration and make update calculation more efficient.
Note
Peer group members can span multiple logical IP subnets, and can transmit, or pass along, routes from one peer group member to another.
Once a peer group is created with the neighbor peer-group command, it can be configured with the neighbor commands. By default, members of the peer group inherit all the configuration options of the peer group. Members also can be configured to override the options that do not affect outbound updates.
Peer group members will always inherit the following configuration options: remote-as (if configured), version, update-source, out-route-map, out-filter-list, out-dist-list, minimum-advertisement-interval, and next-hop-self. All the peer group members will inherit changes made to the peer group.
If a peer group is not configured with a remote-as option, the members can be configured with the neighbor {ip-address | peer-group-name} remote-as command. This command allows you to create peer groups containing external BGP (eBGP) neighbors.
Examples
The following example configurations show how to create these types of neighbor peer group:
•
•
•
iBGP Peer Group
In the following example, the peer group named internal configures the members of the peer group to be iBGP neighbors. By definition, this is an iBGP peer group because the router bgp command and the neighbor remote-as command indicate the same autonomous system (in this case, autonomous system 100). All the peer group members use loopback 0 as the update source and use set-med as the outbound route map. The neighbor internal filter-list 2 in command shows that, except for 171.69.232.55, all the neighbors have filter list 2 as the inbound filter list.
router bgp 100neighbor internal peer-groupneighbor internal remote-as 100neighbor internal update-source loopback 0neighbor internal route-map set-med outneighbor internal filter-list 1 outneighbor internal filter-list 2 inneighbor 171.69.232.53 peer-group internalneighbor 171.69.232.54 peer-group internalneighbor 171.69.232.55 peer-group internalneighbor 171.69.232.55 filter-list 3 ineBGP Peer Group
The following example defines the peer group named external-peers without the neighbor remote-as command. By definition, this is an eBGP peer group because each individual member of the peer group is configured with its respective autonomous system number separately. Thus the peer group consists of members from autonomous systems 200, 300, and 400. All the peer group members have the set-metric route map as an outbound route map and filter list 99 as an outbound filter list. Except for neighbor 171.69.232.110, all of them have 101 as the inbound filter list.
router bgp 100neighbor external-peers peer-groupneighbor external-peers route-map set-metric outneighbor external-peers filter-list 99 outneighbor external-peers filter-list 101 inneighbor 171.69.232.90 remote-as 200neighbor 171.69.232.90 peer-group external-peersneighbor 171.69.232.100 remote-as 300neighbor 171.69.232.100 peer-group external-peersneighbor 171.69.232.110 remote-as 400neighbor 171.69.232.110 peer-group external-peersneighbor 171.69.232.110 filter-list 400 inMultiprotocol BGP Peer Group
In the following example, all members of the peer group are multicast-capable:
router bgp 100neighbor 10.1.1.1 remote-as 1neighbor 172.16.2.2 remote-as 2address-family ipv4 multicastneighbor mygroup peer-groupneighbor 10.1.1.1 peer-group mygroupneighbor 172.16.2.2 peer-group mygroupneighbor 10.1.1.1 activateneighbor 172.16.2.2 activateRelated Commands
neighbor prefix-list
To distribute BGP neighbor information as specified in a prefix list, use the neighbor prefix-list command in address family or router configuration mode. To remove an entry, use the no form of this command.
neighbor {ip-address | peer-group-name} prefix-list prefix-list-name {in | out}
no neighbor {ip-address | peer-group-name} prefix-list prefix-list-name {in |out}
Syntax Description
Defaults
No BGP neighbor is specified.
Command Modes
Address family configuration
Router configuration
Command History
12.0
This command was introduced.
11.0
The peer-group-name argument was added.
12.0(7)T
Address family configuration mode was added.
Usage Guidelines
Using prefix lists is one of two ways to filter BGP advertisements. The other way is to use AS-path filters, as with the ip as-path access-list global configuration command and the neighbor filter-list command, and access or prefix lists, as with the neighbor distribute-list command.
If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command. Specifying the command with an IP address will override the value inherited from the peer group.
Note
Examples
The following router configuration mode example applies the prefix list named abc to incoming advertisements to neighbor 120.23.4.1:
router bgp 109network 10.108.0.0neighbor 120.23.4.1 prefix-list abc inThe following address family configuration mode example applies the prefix list named abc to incoming advertisements to neighbor 120.23.4.1:
router bgp 109address-family ipv4 unicastnetwork 10.108.0.0neighbor 120.23.4.1 prefix-list abc inThe following example applies the prefix list named CustomerA to outgoing advertisements to neighbor 120.23.4.1:
router bgp 109network 10.108.0.0neighbor 120.23.4.1 prefix-list CustomerA outRelated Commands
neighbor remote-as
To add an entry to the BGP or multiprotocol BGP neighbor table, use the neighbor remote-as command in router configuration mode. To remove an entry from the table, use the no form of this command.
neighbor {ip-address | peer-group-name} remote-as as-number
no neighbor {ip-address | peer-group-name} remote-as as-number
Syntax Description
ip-address
IP address of the neighbor.
peer-group-name
Name of a BGP peer group.
as-number
Autonomous system to which the neighbor belongs.
Defaults
There are no BGP or multiprotocol BGP neighbor peers.
Command Modes
Router configuration
Command History
Usage Guidelines
Specifying a neighbor with an autonomous system number that matches the autonomous system number specified in the router bgp global configuration command identifies the neighbor as internal to the local autonomous system. Otherwise, the neighbor is considered external.
If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
By default, neighbors that are defined using the neighbor remote-as command in router configuration mode exchange only unicast address prefixes. To exchange other address prefix types, such as multicast and Virtual Private Network (VPN) Version 4, neighbors must also be activated using the neighbor activate command in address family configuration mode.
Examples
The following example specifies that a router at the address 10.108.1.2 is a neighbor in autonomous system number 109:
router bgp 110network 10.108.0.0neighbor 10.108.1.2 remote-as 109The following example assigns a BGP router to autonomous system 109, and two networks are listed as originating in the autonomous system. Then the addresses of three remote routers (and their autonomous systems) are listed. The router being configured will share information about networks 10.108.0.0 and 192.31.7.0 with the neighbor routers. The first router listed is in the same Class B network address space, but in a different autonomous system; the second neighbor remote-as command illustrates specification of an internal neighbor (with the same autonomous system number) at address 10.108.234.2; and the last neighbor remote-as command specifies a neighbor on a different network.
router bgp 109network 10.108.0.0network 192.31.7.0neighbor 10.108.200.1 remote-as 167neighbor 10.108.234.2 remote-as 109neighbor 150.136.64.19 remote-as 99The following example configures neighbor 10.108.1.1 in autonomous system 1 to exchange only multicast routes:
router bgp 109neighbor 10.108.1.1 remote-as 1neighbor 131.108 1.2 remote-as 1neighbor 172.16.2.2 remote-as 2address-family ipv4 multicastneighbor 10.108.1.1 activateneighbor 131.108 1.2 activateneighbor 172.16.2.2 activateThe following example configures neighbor 10.108.1.1 in autonomous system 1 to exchange only unicast routes:
router bgp 109neighbor 10.108.1.1 remote-as 1neighbor 131.108 1.2 remote-as 1neighbor 172.16.2.2 remote-as 2Related Commands
neighbor remote-as
Creates a BGP peer group.
router bgp
Configures the BGP routing process.
neighbor remove-private-as
To remove private autonomous system numbers from t in outbound routing updates, use the neighbor remove-private-as command in router configuration mode. To disable this function, use the no form of this command.
neighbor {ip-address | peer-group-name} remove-private-as
no neighbor {ip-address | peer-group-name} remove-private-as
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
This command is available for external BGP (eBGP) neighbors only.
When an update is passed to the external neighbor, if the autonomous system path includes private autonomous system numbers, the software will drop the private autonomous system numbers.
If the autonomous system path includes both private and public autonomous system numbers, the software considers this to be a configuration error and does not remove the private autonomous system numbers.
If the autonomous system path contains the autonomous system number of the eBGP neighbor, the private autonomous system numbers will not be removed.
If this command is used with confederation, it will work as long as the private autonomous system numbers follow the confederation portion of the autonomous path.
The private autonomous system values are from 64512 to 65535.
Examples
The following example shows a configuration that will remove the private autonomous system number from the updates sent to 172.16.2.33. The result is that the autonomous system path for the paths advertised by 10.108.1.1 through autonomous system 100 will just contain "100" (as seen by autonomous system 2051).
router bgp 100neighbor 10.108.1.1 description peer with private-asneighbor 10.108.1.1 remote-as 65001neighbor 172.16.2.33 description eBGP peerneighbor 172.16.2.33 remote-as 2051neighbor 172.16.2.33 remove-private-asrouter-in-AS100# show ip bgp 10.0.0.0BGP routing table entry for 10.0.0.0/8, version 15Paths: (1 available, best #1)Advertised to non peer-group peers:172.16.2.336500110.108.1.1 from 10.108.1.1Origin IGP, metric 0, localpref 100, valid, external, bestrouter-in-AS2501# show ip bgp 10.0.0.0BGP routing table entry for 10.0.0.0/8, version 3Paths: (1 available, best #1)Not advertised to any peer2172.16.2.32 from 172.16.2.32Origin IGP, metric 0, localpref 100, valid, external, bestRelated Commands
neighbor remote-as
Allows entries to the BGP neighbor table.
show ip bgp
Displays entries in the BGP routing table.
neighbor route-map
To apply a route map to incoming or outgoing routes, use the neighbor route-map command in address family or router configuration mode. To remove a route map, use the no form of this command.
neighbor {ip-address | peer-group-name} route-map map-name {in | out}
no neighbor {ip-address | peer-group-name} route-map map-name {in | out}
Syntax Description
Defaults
No route maps are applied to a peer.
Command Modes
Address family configuration
Router configuration
Command History
10.0
This command was introduced.
12.0(7)T
Address family configuration mode was added.
Usage Guidelines
When specified in address family configuration mode, this command applies a route map to that particular address family only. When specified in router configuration mode, this command applies a route map to IP Version 4 unicast routes only.
If an outbound route map is specified, it is proper behavior to only advertise routes that match at least one section of the route map.
If you specify a BGP or multiprotocol BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command. Specifying the command for a neighbor overrides the inbound policy that is inherited from the peer group.
Examples
The following router configuration mode example applies a route map named internal-map to a BGP incoming route from 172.16.70.24:
router bgp 5neighbor 172.16.70.24 route-map internal-map inroute-map internal-mapmatch as-path 1set local-preference 100The following address family configuration mode example applies a route map named internal-map to a multiprotocol BGP incoming route from 172.16.70.24:
router bgp 5address-family ipv4 multicastneighbor 172.16.70.24 route-map internal-map inroute-map internal-mapmatch as-path 1set local-preference 100Related Commands
neighbor route-reflector-client
To configure the router as a BGP route reflector and configure the specified neighbor as its client, use the neighbor route-reflector-client command in address family or router configuration mode. To indicate that the neighbor is not a client, use the no form of this command.
neighbor ip-address route-reflector-client
no neighbor ip-address route-reflector-client
Syntax Description
Defaults
There is no route reflector in the autonomous system.
Command Modes
Address family configuration
Router configuration
Command History
11.1
This command was introduced.
12.0(7)T
Address family configuration mode was added.
Usage Guidelines
By default, all internal BGP (iBGP) speakers in an autonomous system must be fully meshed, and neighbors do not readvertise iBGP learned routes to neighbors, thus preventing a routing information loop. When all the clients are disabled, the local router is no longer a route reflector.
If you use route reflectors, all iBGP speakers need not be fully meshed. In the route reflector model, an Interior BGP peer is configured to be a route reflector responsible for passing iBGP learned routes to iBGP neighbors. This scheme eliminates the need for each router to talk to every other router.
Use the neighbor route-reflector-client command to configure the local router as the route reflector and the specified neighbor as one of its clients. All the neighbors configured with this command will be members of the client group and the remaining iBGP peers will be members of the nonclient group for the local route reflector.
The bgp client-to-client reflection command controls client-to-client reflection.
Examples
In the following router configuration mode example, the local router is a route reflector. It passes learned iBGP routes to the neighbor at 172.16.70.24.
router bgp 5neighbor 172.16.70.24 route-reflector-clientIn the following address family configuration mode example, the local router is a route reflector. It passes learned iBGP routes to the neighbor at 172.16.70.24.
router bgp 5address-family ipv4 unicastneighbor 172.16.70.24 route-reflector-clientRelated Commands
neighbor send-community
To specify that a communities attribute should be sent to a BGP neighbor, use the neighbor send-community command in address family or router configuration mode. To remove the entry, use the no form of this command.
neighbor {ip-address | peer-group-name} send-community [both | standard | extended]
no neighbor {ip-address | peer-group-name} send-community
Syntax Description
Defaults
No communities attribute is sent to any neighbor.
Command Modes
Address family configuration
Router configuration
Command History
10.3
This command was introduced.
11.0
The peer-group-name argument was added.
12.0(7)T
Address family configuration mode was added.
Usage Guidelines
If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
Examples
In the following router configuration mode example, the router belongs to autonomous system 109 and is configured to send the communities attribute to its neighbor at IP address 172.16.70.23:
router bgp 109neighbor 172.16.70.23 send-communityIn the following address family configuration mode example, the router belongs to autonomous system 109 and is configured to send the communities attribute to its neighbor at IP address 172.16.70.23:
router bgp 109address-family ipv4 multicastneighbor 172.16.70.23 send-communityRelated Commands
neighbor shutdown
To disable a neighbor or peer group, use the neighbor shutdown command in router configuration mode. To reenable the neighbor or peer group, use the no form of this command.
neighbor {ip-address | peer-group-name} shutdown
no neighbor {ip-address | peer-group-name} shutdown
Syntax Description
Defaults
No change is made to the status of any BGP neighbor or peer group.
Command Modes
Router configuration
Command History
Usage Guidelines
The neighbor shutdown command terminates any active session for the specified neighbor or peer group and removes all associated routing information. In the case of a peer group, a large number of peering sessions could be terminated suddenly.
To display a summary of BGP neighbors and peer group connections, use the show ip bgp summary command. Those neighbors with an Idle status and the Admin entry have been disabled by the neighbor shutdown command.
"State/PfxRcd" shows the current state of the BGP session or the number of prefixes the router has received from a neighbor or peer group. When the maximum number (as set by the neighbor maximum-prefix command) is reached, the string "PfxRcd" appears in the entry, the neighbor is shut down, and the connection is idle.
Examples
The following example disables any active session for the neighbor 172.16.70.23:
neighbor 172.16.70.23 shutdownThe following example disables all peering sessions for the peer group named internal:
neighbor internal shutdownRelated Commands
neighbor maximum-prefix
Controls how many prefixes can be received from a neighbor.
show ip bgp summary
Displays the status of all BGP connections.
neighbor soft-reconfiguration
To configure the Cisco IOS software to start storing updates, use the neighbor soft-reconfiguration command in router configuration mode. To not store received updates, use the no form of this command.
neighbor {ip-address | peer-group-name} soft-reconfiguration [inbound]
no neighbor {ip-address | peer-group-name} soft-reconfiguration [inbound]
Syntax Description
ip-address
IP address of the BGP-speaking neighbor.
peer-group-name
Name of a BGP peer group.
inbound
(Optional) Indicates that the update to be stored is an incoming update.
Defaults
Soft reconfiguration is not enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
Entering this command starts the storage of updates, which is required to do inbound soft reconfiguration. Outbound BGP soft reconfiguration does not require inbound soft reconfiguration to be enabled.
To use soft reconfiguration, or soft reset, without preconfiguration, both BGP peers must support the soft route refresh capability, which is advertised in the open message sent when the peers establish a TCP session. Routers running Cisco IOS software releases prior to Release 12.1 do not support the route refresh capability and must clear the BGP session using the neighbor soft-reconfiguration command. Clearing the BGP session using the neighbor soft-reconfiguration command has a negative effect on network operations and should be used only as a last resort. Routers running Cisco IOS software Release 12.1 or later releases support the route refresh capability and dynamic soft resets, and can use the clear ip bgp {* | ip-address | peer-group name} in command to clear the BGP session.
To determine whether a BGP router supports this capability, use the show ip bgp neighbors command. If a router supports the route refresh capability, the following message is displayed:
Received route refresh capability from peer.If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
Examples
The following example enables inbound soft reconfiguration for the neighbor 10.108.1.1. All the updates received from this neighbor will be stored unmodified, regardless of the inbound policy. When inbound soft reconfiguration is done later, the stored information will be used to generate a new set of inbound updates.
router bgp 100neighbor 10.108.1.1 remote-as 200neighbor 10.108.1.1 soft-reconfiguration inboundRelated Commands
neighbor timers
To set the timers for a specific BGP peer or peer group, use the neighbor timers command in router configuration mode. To clear the timers for a specific BGP peer or peer group, use the no form of this command.
neighbor [ip-address | peer-group-name] timers keepalive holdtime
no neighbor [ip-address | peer-group-name] timers keepalive holdtime
Syntax Description
Defaults
keepalive: 60 seconds
holdtime: 180 seconds
Command Modes
Router configuration
Command History
Usage Guidelines
The timers configured for a specific neighbor or peer group override the timers configured for all BGP neighbors using the timers bgp command.
Examples
The following example changes the keepalive timer to 70 seconds and the hold-time timer to 210 seconds for the BGP peer 192.98.47.0:
router bgp 109 neighbor 192.98.47.0 timers 70 210neighbor unsuppress-map
To selectively advertise routes previously suppressed by the aggregate-address command, use the neighbor unsuppress-map command in address family or router configuration mode. To restore the system to the default condition, use the no form of this command.
neighbor {ip-address | peer-group-name} unsuppress-map route-map-name
no neighbor {ip-address | peer-group-name} unsuppress-map route-map-name
Syntax Description
ip-address
IP address of the BGP-speaking neighbor.
peer-group-name
Name of a BGP peer group.
route-map-name
Name of a route map.
Command Default
No routes are unsuppressed.
Command Modes
Address family configuration
Router configurationCommand History
12.0(5)T
This command was introduced.
12.0(5)T
Address family configuration mode was added.
Usage Guidelines
Use of the neighbor unsuppress-map command allows specified suppressed routes to be advertised.
Examples
The following BGP router configuration shows that routes specified by a route map named internal-map are suppressed:
access-list 3 deny 172.16.16.6access-list 3 permit anyroute-map map1 permit 10match ip address 3!router bgp 65000network 172.16.0.0neighbor 192.168.1.2 remote-as 40000aggregate-address 172.0.0.0 255.0.0.0 suppress-map map1neighbor 192.168.1.2 unsuppress-map map1neighbor 192.168.1.2 activateThe following example shows the routes specified by internal-map being unsuppressed for neighbor 172.16.16.6:
router bgp 100address-family ipv4 multicastnetwork 172.16.0.0neighbor 172.16.16.6 unsuppress-map internal-mapRelated Commands
neighbor update-source
To have the Cisco IOS software allow Border Gateway Protocol (BGP) sessions to use a specific operational interface for TCP connections, use the neighbor update-source command in router configuration mode. To restore the interface assignment to the closest interface, which is called the best local address, use the no form of this command.
neighbor {ip-address | peer-group-name} update-source interface-type
no neighbor {ip-address | peer-group-name} update-source interface-type
Syntax Description
ip-address
IP address of the BGP-speaking neighbor.
peer-group-name
Name of a BGP peer group.
interface-type
Interface to be used as the source.
Defaults
Best local address
Command Modes
Router configuration
Command History
Usage Guidelines
This command works in conjunction with any specified interface on the router. The loopback interface is the interface that is most commonly used with this feature. For more information, refer to the loopback interface feature described in the "Interface Configuration Overview" chapter of the Cisco IOS Interface Configuration Guide.
If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
Examples
The following example sources BGP TCP connections for the specified neighbor with the IP address of the loopback interface rather than the best local address:
router bgp 110network 172.16.0.0neighbor 172.16.2.3 remote-as 110 neighbor 172.16.2.3 update-source Loopback0Related Commands
neighbor version
To configure the Cisco IOS software to accept only a particular BGP version, use the neighbor version command in router configuration mode. To use the default version level of a neighbor, use the no form of this command.
neighbor {ip-address | peer-group-name} version number
no neighbor {ip-address | peer-group-name} version number
Syntax Description
Defaults
BGP Version 4
Command Modes
Router configuration
Command History
Usage Guidelines
Entering this command disables dynamic version negotiation.
Note
The Cisco implementation of BGP in Cisco IOS Release 12.0(6)T or later releases supports BGP Version 4 only and does not support dynamic negotiation down to Version 2.If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
Examples
The following example locks down to Version 4 of the BGP protocol:
router bgp 109 neighbor 131.104.27.2 version 4Related Commands
neighbor weight
To assign a weight to a neighbor connection, use the neighbor weight command in address family or router configuration mode. To remove a weight assignment, use the no form of this command.
neighbor {ip-address | peer-group-name} weight number
no neighbor {ip-address | peer-group-name} weight number
Syntax Description
ip-address
IP address of the neighbor.
peer-group-name
Name of a BGP peer group.
number
Weight to assign. Acceptable values are from 0 to 65535.
Defaults
Routes learned through another BGP peer have a default weight of 0 and routes sourced by the local router have a default weight of 32768.
Command Modes
Address family configuration
Router configuration
Command History
10.0
This command was introduced.
12.0(7)T
Address family configuration mode was added.
Usage Guidelines
All routes learned from this neighbor will have the assigned weight initially. The route with the highest weight will be chosen as the preferred route when multiple routes are available to a particular network.
The weights assigned with the set weight route-map command override the weights assigned using the neighbor weight command.
Note
If you specify a BGP peer group by using the peer-group-name argument, all the members of the peer group will inherit the characteristic configured with this command.
Examples
The following router configuration mode example sets the weight of all routes learned via 172.16.12.1 to 50:
router bgp 109 neighbor 172.16.12.1 weight 50The following address family configuration mode example sets the weight of all routes learned via 172.16.12.1 to 50:
router bgp 109address-family ipv4 multicast neighbor 172.16.12.1 weight 50Related Commands
