Table Of Contents
bgp client-to-client reflection
default-information originate (BGP)
default-metric (BGP, OSPF, and RIP)
neighbor advertisement-interval
neighbor peer-group (assigning members)
neighbor peer-group (creating)
neighbor route-reflector-client
neighbor soft-reconfiguration inbound
BGP Commands
Use the commands in this chapter to configure and monitor Border Gateway Protocol (BGP). For BGP configuration information and examples, refer to the "Configuring BGP" chapter of the Network Protocols Configuration Guide, Part 1.
aggregate-address
To create an aggregate entry in a BGP routing table, use the aggregate-address router configuration command. To disable this feature, use the no form of this command.
aggregate-address address mask [as-set] [summary-only] [suppress-map map-name]
[advertise-map map-name] [attribute-map map-name]
no aggregate-address address mask [as-set] [summary-only] [suppress-map map-name]
[advertise-map map-name] [attribute-map map-name]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can implement aggregate routing in BGP either by redistributing an aggregate route into BGP or by using this conditional aggregate routing feature.
Using the aggregate-address command with no arguments will create an aggregate entry in the BGP routing table if there are any more-specific BGP routes available that fall in the specified range. The aggregate route will be advertised as coming from your autonomous system and has the atomic aggregate attribute set to show that information might be missing. (By default, the atomic aggregate attribute is set unless you specify the as-set keyword.)
Using the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword, but the path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized. Do not use this form of aggregate-address when aggregating many paths, because this route must be continually withdrawn and re-updated as autonomous system path reachability information for the summarized routes changes.
Using the summary-only keyword not only creates the aggregate route (for example, 193.*.*.*) but will also suppress advertisements of more-specific routes to all neighbors. If you only want to suppress advertisements to certain neighbors, you may use the neighbor distribute-list command, with caution. If a more specific route leaks out, all BGP speakers will prefer that route over the less-specific aggregate you are generating (using longest-match routing).
Using the suppress-map keyword creates the aggregate route but suppresses advertisement of specified routes. You can use the match clauses of route maps to selectively suppress some more specific routes of the aggregate and leave others unsuppressed. IP access lists and autonomous system path access lists match clauses are supported.
Example
In the following example, an aggregate address is created. The path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized.
router bgp 5aggregate-address 193.0.0.0 255.0.0.0 as-setRelated Commands
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match as-path
match ip address
route-mapauto-summary
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary router configuration command. To disable this feature and transmit subprefix routing information across classful network boundaries, use the no form of this command.
auto-summary
no auto-summarySyntax Description
This command has no arguments or keywords.
Default
Enabled (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Route summarization reduces the amount of routing information in the routing tables.
By default, BGP does not accept subnets redistributed from IGP. To advertise and carry subnet routes in BGP, use an explicit network command or the no auto-summary command. If you disable auto-summarization and have not entered a network command, you will not advertise network routes for networks with subnet routes unless they contain a summary route.
Example
In the following example, network numbers are not summarized automatically:
router bgp 6no auto-summarybgp always-compare-med
To allow the comparison of the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems, use the bgp always-compare-med router configuration command. To disallow the comparison, use the no form of this command.
bgp always-compare-med
no bgp always-compare-medSyntax Description
This command has no arguments or keywords.
Default
The Cisco IOS software does not compare MEDs for paths from neighbors in different autonomous systems.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
The MED is one of the parameters that is considered when selecting the best path among many alternative paths. The path with a lower MED is preferred over a path with a higher MED.
By default, during the best-path selection process, MED comparison is done only among paths from the same autonomous system. This command changes the default behavior by allowing comparison of MEDs among paths regardless of the autonomous system from which the paths are received.
Example
In the following example, the BGP speaker in autonomous system 100 is configured to compare MEDs among alternative paths, regardless of the autonomous system from which the paths are received:
router bgp 109bgp always-compare-medbgp client-to-client reflection
To restore route reflection from a BGP route reflector to clients, use the bgp client-to-client reflection router configuration command. To disable client-to-client reflection, use the no form of this command.
bgp client-to-client reflection
no bgp client-to-client reflectionSyntax Description
This command has no arguments or keywords.
Default
When a route reflector is configured, the route reflector reflects routes from a client to other clients.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
By default, the clients of a route reflector are not required to be fully meshed and the routes from a client are reflected to other clients. However, if the clients are fully meshed, route reflection is not required. Use the no bgp client-to-client reflection command to disable client-to-client reflection.
If client-to-client reflection is enabled, the clients of a route reflector cannot be members of a peer group.
Example
In the following example, the local router is a route reflector. The three neighbors are fully meshed, so client-to-client reflection is disabled.
router bgp 5neighbor 155.24.95.22 route-reflector-clientneighbor 155.24.95.23 route-reflector-clientneighbor 155.24.95.24 route-reflector-clientno bgp client-to-client reflectionRelated Commands
You can use the master indexes or search online to find documentation of related commands.
bgp cluster-id
neighbor route-reflector-client
show ip bgpbgp cluster-id
To configure the cluster ID if the BGP cluster has more than one route reflector, use the bgp cluster-id router configuration command. To remove the cluster ID, use the no form of this command.
bgp cluster-id cluster-id
no bgp cluster-id cluster-idSyntax Description
Default
The router ID of the single route reflector in a cluster
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Together, a route reflector and its clients form a cluster.
Usually a cluster of clients will have a single route reflector. In that case, the cluster is identified by the router ID of the route reflector. In order to increase redundancy and avoid a single point of failure, a cluster might have more than one route reflector. In this case, all route reflectors in the cluster must be configured with the 4-byte cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster.
If the cluster has more than one route reflector, use this command to configure the cluster ID.
Example
In the following example, the local router is one of the route reflectors serving the cluster. It is configured with the cluster ID to identify the cluster.
router bgp 5neighbor 198.92.70.24 route-reflector-clientbgp cluster-id 50000Related Commands
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bgp client-to-client reflection
neighbor route-reflector-client
show ip bgpbgp confederation identifier
To specify a BGP confederation identifier, use the bgp confederation identifier router configuration command. To remove the confederation identifier, use the no form of this command.
bgp confederation identifier autonomous-system
no bgp confederation identifier autonomous-systemSyntax Description
Default
No confederation identifier is configured.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Another way to reduce the IBGP mesh is to divide an autonomous system into multiple autonomous systems and group them into a single confederation. Each autonomous system is fully meshed within itself, and has a few connections to another autonomous system in the same confederation. Even though the peers in different autonomous systems have EBGP sessions, they exchange routing information as if they are IBGP peers. Specifically, the next-hop and local preference information is preserved. This enables to you to retain a single Interior Gateway Protocol (IGP) for all the autonomous systems. To the outside world, the confederation looks like a single autonomous system.
Example
In the following example, the autonomous system is divided into autonomous systems 4001, 4002, 4003, 4004, 4005, 4006, and 4007 and identified by the confederation identifier 5. Neighbor 1.2.3.4 is someone inside your routing domain confederation. Neighbor 3.4.5.6 is someone outside your routing domain confederation. To the outside world, there appears to be a single autonomous system with the number 5.
router bgp 4001bgp confederation identifier 5bgp confederation peers 4002 4003 4004 4005 4006 4007neighbor 1.2.3.4 remote-as 4002neighbor 3.4.5.6 remote-as 510Related Commands
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bgp confederation peers
To configure the autonomous systems that belong to the confederation, use the bgp confederation peers router configuration command. To remove an autonomous system from the confederation, use the no form of this command.
bgp confederation peers autonomous-system [autonomous-system]
no bgp confederation peers autonomous-system [autonomous-system]Syntax Description
Default
No confederation peers are configured.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
The autonomous systems specified in this command are visible internally to a confederation. Each autonomous system is fully meshed within itself. The bgp confederation identifier command specifies the confederation to which the autonomous systems belong.
Example
The following example specifies that autonomous systems 1090, 1091, 1092, and 1093 belong to a single confederation:
router bgp 1090bgp confederation peers 1091 1092 1093Related Commands
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bgp dampening
To enable BGP route dampening or change various BGP route dampening factors, use the bgp dampening global configuration command. To disable the feature or restore the default values, use the no form of this command.
bgp dampening [half-life reuse suppress max-suppress-time] [route-map map]
no bgp dampening [half-life reuse suppress max-suppress-time] [route-map map]Syntax Description
Default
Disabled by default.
half-life is 15 minutes
reuse is 750
suppress is 2000
max-suppress-time is 4 times half-lifeCommand Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
If this command is used with no arguments, it enables BGP route dampening. The arguments half-life, reuse, suppress, and max-suppress-time are position-dependent. Therefore, if any of them are used, they must all be specified.
Example
The following example sets the half-life to 30 minutes, the reuse value to 1500, the suppress value to 10000; and the maximum suppress time to 120 minutes:
bgp dampening 30 1500 10000 120Related Commands
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clear ip bgp dampening
clear ip bgp flap-statistics
show ip bgp dampened-paths
show ip bgp flap-statisticsbgp default local-preference
To change the default local preference value, use the bgp default local-preference router configuration command. To return to the default setting, use the no form of this command.
bgp default local-preference value
no bgp default local-preference valueSyntax Description
Default
Local preference value of 100
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Generally, the default value of 100 allows you to easily define a particular path as less preferable than paths with no local preference attribute. The preference is sent to all routers and access servers in the local autonomous system.
Example
In the following example, the default local preference value is raised from the default of 100 to 200:
router bgp 200bgp default local-preference 200Related Commands
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set local-preference
bgp fast-external-fallover
To immediately reset the BGP sessions of any directly adjacent external peers if the link used to reach them goes down, use the bgp fast-external-fallover router configuration command. To disable this feature, use the no form of this command.
bgp fast-external-fallover
no bgp fast-external-falloverSyntax Description
This command has no arguments or keywords.
Default
Enabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
In the following example, the automatic resetting of BGP sessions is disabled:
router bgp 109no bgp fast-external-falloverclear ip bgp
To reset a BGP connection using BGP soft reconfiguration, use the clear ip bgp EXEC command at the system prompt.
clear ip bgp {* | address | peer-group name} [soft [in | out]]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
If you specify BGP soft reconfiguration, by including the soft keyword, the sessions are not reset and the router sends all routing updates again. To generate new inbound updates without resetting the BGP session, the local BGP speaker should store all received updates without modification regardless of whether it is accepted by the inbound policy. This process is memory intensive and should be avoided if possible. Outbound BGP soft configuration does not have any memory overhead. You can trigger an outbound reconfiguration on the other side of the BGP session to make the new inbound policy take effect.
Use this command whenever any of the following changes occur:
•
Additions or changes to the BGP-related access lists
•
•
•
•
•
Example
The following example resets all current BGP sessions:
clear ip bgp *Related Commands
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clear ip bgp dampening
To clear BGP route dampening information and unsuppress the suppressed routes, use the clear ip bgp dampening EXEC command.
clear ip bgp dampening [address mask]
Syntax Description
address
(Optional) IP address of the network about which to clear dampening information.
mask
(Optional) Network mask applied to the address.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Example
The following example clears route dampening information about the route to network 150.0.0.0 and unsuppresses its suppressed routes:
clear ip bgp dampening 150.0.0.0 255.255.0.0Related Commands
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bgp dampening
show ip bgp dampened-pathsclear ip bgp flap-statistics
To clear BGP flap statistics, use the clear ip bgp flap-statistics EXEC command.
clear ip bgp flap-statistics [{regexp regexp} | {filter-list list} | {address mask}]
clear ip bgp address flap-statisticsSyntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
If no arguments or keywords are specified, the router clear flap statistics for all routes.
The flap statistics for a route are also cleared when a BGP peer is reset. Although the reset withdraws the route, there is no penalty applied in this instance, even though route flap dampening is enabled.
Example
The following example clears all of the flap statistics for paths that pass access list 3:
clear ip bgp flap-statistics filter-list 3Related Commands
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clear ip bgp peer-group
To remove all the members of a BGP peer group, use the clear ip bgp peer-group EXEC command.
clear ip bgp peer-group tag
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Example
The following example removes all members from the BGP peer group internal:
clear ip bgp peer-group internalRelated Commands
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neighbor peer-group (assigning members)
default-information originate (BGP)
To allow the redistribution of network 0.0.0.0 into BGP, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate
no default-information originateSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The same functionality will result from the network 0.0.0.0 command, using the network router configuration command.
Example
The following example configures BGP to redistribute network 0.0.0.0 into BGP:
router bgp 164default-information originatedefault-metric (BGP, OSPF, and RIP)
To set default metric values for the BGP, OSPF, and RIP routing protocols, use this form of the default-metric router configuration command. To return to the default state, use the no form of this command.
default-metric number
no default-metric numberSyntax Description
Default
Built-in, automatic metric translations, as appropriate for each routing protocol
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The default-metric command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.
In BGP, this sets the Multi Exit Discriminator (MED) metric. (The name of this metric for BGP Versions 2 and 3 is INTER_AS.)
Example
The following example shows a router in autonomous system 109 using both the RIP and the OSPF routing protocols. The example advertises OSPF-derived routes using the RIP protocol and assigns the IGRP-derived routes a RIP metric of 10.
router ripdefault-metric 10redistribute ospf 109Related Commands
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redistribute
distance bgp
To allow the use of external, internal, and local administrative distances that could be a better route to a node, use the distance bgp router configuration command. To return to the default values, use the no form of this command.
distance bgp external-distance internal-distance local-distance
no distance bgpSyntax Description
Defaults
external-distance: 20
internal-distance: 200
local-distance: 200Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.
Use this command if another protocol is known to be able to provide a better route to a node than was actually learned via external BGP, or if some internal routes should really be preferred by BGP.
Note
Example
In the following example, internal routes are known to be preferable to those learned through the IGP, so the administrative distance values are set accordingly:
router bgp 109network 131.108.0.0neighbor 129.140.6.6 remote-as 123neighbor 128.125.1.1 remote-as 47distance bgp 20 20 200ip as-path access-list
To define a BGP-related access list, use the ip as-path access-list global configuration command. To disable use of the access list, use the no form of this command.
ip as-path access-list access-list-number {permit | deny} as-regular-expression
no ip as-path access-list access-list-number {permit | deny} as-regular-expressionSyntax Description
Default
No access lists are defined.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can specify an access list filter on both inbound and outbound BGP routes. In addition, you can assign weights based on a set of filters. Each filter is an access list based on regular expressions. If the regular expression matches the representation of the autonomous system path of the route as an ASCII string, then the permit or deny condition applies. The autonomous system path does not contain the local autonomous system number. Use the ip as-path access-list global configuration command to define an BGP access list, and the neighbor router configuration command to apply a specific access list.
Example
The following example specifies that the BGP neighbor with IP address 128.125.1.1 is not sent advertisements about any path through or from the adjacent autonomous system 123:
ip as-path access-list 1 deny _123_ip as-path access-list 1 deny ^123$router bgp 109network 131.108.0.0neighbor 129.140.6.6 remote-as 123neighbor 128.125.1.1 remote-as 47neighbor 128.125.1.1 filter-list 1 outRelated Commands
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neighbor distribute-list
neighbor filter-listip community-list
To create a community list for BGP and control access to it, use the ip community-list global configuration command. To delete the community list, use the no form of this command.
ip community-list community-list-number {permit | deny} community-number
no ip community-list community-list-numberSyntax Description
community-list-number
Integer from 1 to 99 that identifies one or more permit or deny groups of communities.
permit
Permits access for a matching condition.
deny
Denies access for a matching condition.
community-number
Community number configured by a set community command. Valid value is one of the following:
•
•
•
•
Default
Once you permit a value for the community number, the community list defaults to an implicit deny for everything else.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Example
In the following example, the Cisco IOS software permits all routes except the routes with the communities 5 and 10 or 10 and 15:
ip community-list 1 deny 5 10ip community-list 1 deny 10 15ip community-list 1 permit internetRelated Commands
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match as-path
To match a BGP autonomous system path access list, use the match as-path route-map configuration command. To remove a path list entry, use the no form of this command.
match as-path path-list-number
no match as-path path-list-numberSyntax Description
Default
No path lists are defined.
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The values set by the match and set commands override global values. For example, the weights assigned with the match as-path and set weight route-map commands override the weights assigned using the neighbor weight and neighbor filter-list commands.
A route map can have several parts. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure a second route-map section with an explicit match specified.
The implemented weight is based on the first matched autonomous system path.
Example
In the following example, the autonomous system path is set to match BGP autonomous system path access list 20:
route-map igp2bgpmatch as-path 20Related Commands
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match community-list
match interface
match ip address
match ip next-hop
match ip route-source
match metric
match route-type
match tag
route-map
set as-path
set automatic-tag
set community
set level
set local-preference
set metric
set metric-type
set next-hop
set origin
set tag
set weightmatch community-list
To match a BGP community, use the match community-list route-map configuration command. To remove the community list entry, use the no form of this command.
match community-list community-list-number [exact]
no match community-list community-list-number [exact]Syntax Description
Default
No community list is defined.
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
A route map can have several parts. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure a second route-map section with an explicit match specified.
Matching based on community list is one of the types of match clauses applicable to BGP.
Examples
In the following example, the routes that match community list 1 will have the weight set to 100. Any route that has community 109 will have the weight set to 100.
ip community-list 1 permit 109!route-map set_weightmatch community-list 1set weight 100In the following example, the routes that match community list 1 will have the weight set to 200. Any route that has community 109 alone will have the weight set to 200.
ip community-list 1 permit 109!route-map set_weightmatch community-list 1 exactset weight 200Related Commands
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route-map
set weightneighbor advertisement-interval
To set the minimum interval between the sending of BGP routing updates, use the neighbor advertisement-interval router configuration command. To remove an entry, use the no form of this command.
neighbor {ip-address | peer-group-name} advertisement-interval seconds
no neighbor {ip-address | peer-group-name} advertisement-interval secondsSyntax Description
ip-address
Neighbor's IP address.
peer-group-name
Name of a BGP peer group.
seconds
Time in seconds. Integer from 0 to 600.
Default
30 seconds for external peers and 5 seconds for internal peers.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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.
Example
In the following example, the minimum time between sending BGP routing updates is set to 10 seconds:
router bgp 5neighbor 4.4.4.4 advertisement-interval 10Related Commands
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neighbor peer-group (creating)
neighbor default-originate
To allow a BGP speaker (the local router) to send the default route 0.0.0.0 to a neighbor for use as a default route, use the neighbor default-originate router configuration command. To remove the default route, use the no form of this command.
neighbor {ip-address | peer-group-name} default-originate [route-map map-name]
no neighbor {ip-address | peer-group-name} default-originate [route-map map-name]Syntax Description
ip-address
Neighbor's IP address.
peer-group-name
Name of a BGP peer group.
route-map map-name
(Optional) Name of the route map. The route map allows route 0.0.0.0 to be injected conditionally.
Default
No default route is sent to the neighbor.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
This command does not require the presence of 0.0.0.0 in the local router. When used with a route map, the default route 0.0.0.0 is injected if the route map contains a match ip address clause and there is a route that matches the IP access list exactly. The route map can contain other match clauses also.
Examples
In the following example, the local router injects route 0.0.0.0 to the neighbor 160.89.2.3 unconditionally:
router bgp 109network 160.89.0.0neighbor 160.89.2.3 remote-as 200neighbor 160.89.2.3 default-originateIn the following example, the local router injects route 0.0.0.0 to the neighbor 160.89.2.3 only if there is a route to 198.92.68.0:
router bgp 109network 160.89.0.0neighbor 160.89.2.3 remote-as 200neighbor 160.89.2.3 default-originate route-map default-map!route-map default-map 10 permitmatch ip address 1!access-list 1 permit 198.92.68.0neighbor description
To associate a description with a neighbor, use the neighbor description router configuration command. To remove the description, use the no form of this command.
neighbor {ip-address | peer-group-name} description text
no neighbor {ip-address | peer-group-name} description [text]Syntax Description
Default
There is no description of the neighbor.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3.
Example
In the following example, the description of the neighbor is "peer with abc.com":
router bgp 109network 160.89.0.0neighbor 160.89.2.3 description peer with abc.comneighbor distribute-list
To distribute BGP neighbor information as specified in an access list, use the neighbor distribute-list router configuration command. To remove an entry, use the no form of this command.
neighbor {ip-address | peer-group-name} distribute-list {access-list-number | name} {in | out}
no neighbor {ip-address | peer-group-name} distribute-list {access-list-number | name} {in |
out}Syntax Description
Default
No BGP neighbor is specified.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The peer-group-name argument first appeared in Cisco IOS Release 11.0. The access-list-name argument first appeared in Cisco IOS Release 11.2.
Using distribute 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.
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.
Example
The following example applies list 39 to incoming advertisements to neighbor 120.23.4.1:
router bgp 109network 131.108.0.0neighbor 120.23.4.1 distribute-list 39 inRelated Commands
You can use the master indexes or search online to find documentation of related commands.
ip as-path access-list
neighbor filter-list
neighbor peer-group (creating)neighbor ebgp-multihop
To accept and attempt BGP connections to external peers residing on networks that are not directly connected, use the neighbor ebgp-multihop router configuration command. To return to the default, use the no form of this command.
neighbor {ip-address | peer-group-name} ebgp-multihop [ttl]
no neighbor {ip-address | peer-group-name} ebgp-multihopSyntax Description
ip-address
IP address of the BGP-speaking neighbor.
peer-group-name
Name of a BGP peer group.
ttl
(Optional) Time-to-live in the range 1 to 255 hops.
Default
Only directly connected neighbors are allowed.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The peer-group-name argument first appeared in Cisco IOS Release 11.0.
This feature should only be used under the guidance of technical support staff.
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.
Example
The following example allows connections to or from neighbor 131.108.1.1, which resides on a network that is not directly connected:
router bgp 109neighbor 131.108.1.1 ebgp-multihopRelated Commands
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neighbor peer-group (creating)
neighbor filter-list
To set up a BGP filter, use the neighbor filter-list router configuration command. To disable this function, use the no form of this command.
neighbor {ip-address | peer-group-name} filter-list access-list-number {in | out |
weight weight}
no neighbor {ip-address | peer-group-name} filter-list access-list-number {in | out |
weight weight}Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This command establishes filters on both inbound and outbound BGP routes. Any number of weight filters are allowed on a per-neighbor basis, but only one in or out filter is allowed. The weight of a route affects BGP's route-selection rules.
The implemented weight is based on the first matched autonomous system path. Weights indicated when an autonomous system path is matched override the weights assigned by global neighbor commands. In other words, the weights assigned with the match as-path and set weight route-map commands override the weights assigned using the neighbor weight and neighbor filter-list commands.
See the "Regular Expressions" appendix in the Dial Solutions Command Reference for information on forming regular expressions.
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.
Example
In the following example, the BGP neighbor with IP address 128.125.1.1 is not sent advertisements about any path through or from the adjacent autonomous system 123:
ip as-path access-list 1 deny _123_ip as-path access-list 1 deny ^123$router bgp 109network 131.108.0.0neighbor 129.140.6.6 remote-as 123neighbor 128.125.1.1 remote-as 47neighbor 128.125.1.1 filter-list 1 outRelated Commands
You can use the master indexes or search online to find documentation of related commands.
ip as-path access-list
neighbor distribute-list
neighbor peer-group (creating)
neighbor weightneighbor maximum-prefix
To control how many prefixes can be received from a neighbor, use the neighbor maximum-prefix router configuration command. To disable this function, use the no form of this command.
neighbor {ip-address | peer-group-name} maximum-prefix maximum [threshold]
[warning-only]
no neighbor {ip-address | peer-group-name} maximum-prefix maximumSyntax Description
Default
Disabled; there is no limit on the number of prefixes.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3.
This command allows you to configure a maximum number of prefixes a BGP router is allowed to receive from a peer. It adds another mechanism (in addition to distribute lists, filter lists, and route maps) to control prefixes received from a peer.
When the number of received prefixes exceeds the maximum number configured, the router terminates the peering (by default). However, if the keyword warning-only is configured, the router instead only sends a log message, but continues peering with the sender. If the peer is terminated, the peer stays down until the clear ip bgp command is issued.
Example
In the following example, the maximum number of prefixes allowed from the neighbor at 129.140.6.6 is set to 1000:
router bgp 109network 131.108.0.0neighbor 129.140.6.6 maximum-prefix 1000Related Commands
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neighbor next-hop-self
To disable next-hop processing of BGP updates on the router, use the neighbor next-hop-self router configuration command. To disable this feature, use the no form of this command.
neighbor {ip-address | peer-group-name} next-hop-self
no neighbor {ip-address | peer-group-name} next-hop-selfSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The peer-group-name argument first appeared in Cisco IOS Release 11.0.
This command is useful in nonmeshed networks (such as Frame Relay or X.25) where BGP neighbors may not have direct access to all other neighbors on the same IP subnet.
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.
Example
The following example forces all updates destined for 131.108.1.1 to advertise this router as the next hop:
router bgp 109neighbor 131.108.1.1 next-hop-selfRelated Commands
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neighbor peer-group (creating)
neighbor password
To enable MD5 authentication on a TCP connection between two BGP peers, use the neighbor password router configuration command. To disable this feature, use the no form of this command.
neighbor {ip-address | peer-group-name} password string
no neighbor {ip-address | peer-group-name} passwordSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
You can invoke authentication between two BGP peers, causing each segment sent on the TCP connection between them to be verified. This feature must be configured with the same password on both BGP peers; otherwise, the connection between them will not be made. The authentication feature uses the MD5 algorithm. Specifying this command causes the generation and checking of the MD5 digest on every segment sent on the TCP connection.
Configuring a password for a neighbor will cause an existing session to be torn down and a new one established.
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.
If a router has a password configured for a neighbor, but the neighbor router does not, a message such as the following will appear on the console while the routers attempt to establish a BGP session between them:
%TCP-6-BADAUTH: No MD5 digest from [peer's IP address]:11003 to [local router's IP address]:179Similarly, if the two routers have different passwords configured, a message such as the following will appear on the console:
%TCP-6-BADAUTH: Invalid MD5 digest from [peer's IP address]:11004 to [local router's IP address]:179Example
The following example enables the authentication feature between this router and the BGP neighbor at 131.102.1.1. The password that must also be configured for the neighbor is bla4u00=2nkq.
router bgp 109neighbor 131.108.1.1 password bla4u00=2nkqRelated Commands
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neighbor peer-group (creating)
neighbor peer-group (assigning members)
To configure a BGP neighbor to be a member of a peer group, use the neighbor peer-group router configuration command. To remove the neighbor from the peer group, use the no form of this command.
neighbor ip-address peer-group peer-group-name
no neighbor ip-address peer-group peer-group-nameSyntax Description
ip-address
IP address of the BGP neighbor who belongs to the peer group specified by the tag.
peer-group-name
Name of the BGP peer group to which this neighbor belongs.
Default
There are no BGP neighbors in a peer group.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
The neighbor at the IP address indicated inherits all the configured options of the peer group.
Example
In the following example, three neighbors are assigned to the peer group called internal.
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 inRelated Commands
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neighbor peer-group (creating)
neighbor peer-group (creating)
To create a BGP peer group, use the neighbor peer-group router configuration command. 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-groupSyntax Description
Default
There is no BGP peer group.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Often in a BGP speaker, there are many neighbors 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.
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 can also 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, 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 EBGP neighbors.
Example for an 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, AS 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 inExample for an EBGP Peer Group
In the following example, the peer group external-peers is defined without the neighbor remote-as command. This is what makes it an EBGP peer group. Each individual member of the peer group is configured with its respective AS-number separately. Thus the peer group consists of members from autonomous systems 200, 300, and 400. All the peer group members have 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 inRelated Commands
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clear ip bgp peer-group
neighbor peer-group (assigning members)
show ip bgp peer-groupneighbor remote-as
To add an entry to the BGP neighbor table, use the neighbor remote-as router configuration command. To remove an entry from the table, use the no form of this command.
neighbor {ip-address | peer-group-name} remote-as number
no neighbor {ip-address | peer-group-name} remote-as numberSyntax Description
ip-address
Neighbor's IP address.
peer-group-name
Name of a BGP peer group.
number
Autonomous system to which the neighbor belongs.
Default
There are no BGP neighbor peers.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The peer-group-name argument first appeared in Cisco IOS Release 11.0.
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.
Examples
The following example specifies that a router at the address 131.108.1.2 is a neighbor in autonomous system number 109:
router bgp 110network 131.108.0.0neighbor 131.108.1.2 remote-as 109In the following example, a BGP router is assigned 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 131.108.0.0 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 command illustrates specification of an internal neighbor (with the same autonomous system number) at address 131.108.234.2; and the last neighbor command specifies a neighbor on a different network.
router bgp 109network 131.108.0.0network 192.31.7.0neighbor 131.108.200.1 remote-as 167neighbor 131.108.234.2 remote-as 109neighbor 150.136.64.19 remote-as 99Related Commands
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neighbor peer-group (creating)
neighbor remove-private-as
To remove private autonomous system numbers from the AS-path, a list of autonomous system numbers that a route passes through to reach a BGP peer, in outbound routing updates, use the neighbor remove-private-as router configuration command. 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-asSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3. The peer-group-name argument first appeared in Cisco IOS Release 11.0.
This feature is available for external BGP (EBGP) neighbors only.
When an update is passed to the external neighbor, if the AS-path includes private autonomous system numbers, the software will drop the private autonomous system numbers.
If the AS-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 AS-path contains the autonomous system number of the EBGP neighbor, the private autonomous system numbers will not be removed.
If this feature is used with confederation, it will work as long as the private autonomous system numbers follow the confederation portion of the AS-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 160.89.2.33. The result is that the AS_path for the paths advertised by 131.108.1.1 through autonomous system 100 will just contain "100" (as seen by autonomous system 2051):
router bgp 100network 131.108.1.1 description peer with private-asneighbor 131.108.1.1 remote-as 65001neighbor 160.89.2.33 description eBGP peerneighbor 160.89.2.33 remote-as 2051neighbor 160.89.2.33 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:160.89.2.3365001131.108.1.1 from 131.108.1.1Origin IGP, metric 0, localpref 100, valid, external, bestrouter-in-AS2051# 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 peer2160.89.2.32 from 160.89.2.32Origin IGP, metric 0, localpref 100, valid, external, bestRelated Commands
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neighbor route-map
To apply a route map to incoming or outgoing routes, use the neighbor route-map router configuration command. 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
ip-address
Neighbor's IP address.
peer-group-name
Name of a BGP peer group.
map-name
Name of route map.
in
Apply to incoming routes.
out
Apply to outgoing routes.
Default
No route maps are applied to a peer.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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 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.
Example
In the following example, route map internal-map is applied to incoming route from 198.92.70.24:
router bgp 5neighbor 198.92.70.24 route-map internal-map in!route-map internal-mapmatch as-path 1set local-preference 100Related Commands
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neighbor peer-group (creating)
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 router configuration command. To indicate that the neighbor is not a client, use the no form of this command. When all the clients are disabled, the local router is no longer a route reflector.
neighbor ip-address route-reflector-client
no neighbor ip-address route-reflector-clientSyntax Description
Default
There is no route reflector in the autonomous system.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1.
By default, all 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.
If you use route reflectors, all IBGP speakers need not be fully meshed. In the route reflector model, an internal 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.
If client-to-client reflection is enabled (by default it is enabled), clients of a route reflector cannot be members of a peer group. The bgp client-to-client reflection command controls client-to-client reflection.
Example
In the following example, the local router is a route reflector. It passes learned IBGP routes to the neighbor at 198.92.70.24.
router bgp 5neighbor 198.92.70.24 route-reflector-clientRelated Commands
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bgp client-to-client reflection
bgp cluster-id
show ip bgpneighbor send-community
To specify that a COMMUNITIES attribute should be sent to a BGP neighbor, use the neighbor send-community router configuration command. To remove the entry, use the no form of this command.
neighbor {ip-address | peer-group-name} send-community
no neighbor {ip-address | peer-group-name} send-communitySyntax Description
Default
No COMMUNITIES attribute is sent to any neighbor.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3. The peer-group-name argument first appeared in Cisco IOS Release 11.0.
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.
Example
In the following example, the router belongs to autonomous system 109 and is configured to send the COMMUNITIES attribute to its neighbor at IP address 198.92.70.23:
router bgp 109neighbor 198.92.70.23 send-communityRelated Commands
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match community-list
neighbor peer-group (creating)
set communityneighbor soft-reconfiguration inbound
To configure the Cisco IOS software to start storing received updates, use the neighbor soft-reconfiguration inbound router configuration command. 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 inboundSyntax Description
Default
None
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Entering this command starts the storage of received updates. This is required to do inbound soft reconfiguration. Outbound BGP soft reconfiguration does not require inbound soft reconfiguration to be enabled.
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.
Example
In the following example, inbound soft-reconfiguration is enabled for the neighbor 131.108.1.1. 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 131.108.1.1 remote-as 200neighbor 131.108.1.1 soft-reconfiguration inboundRelated Commands
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neighbor peer-group (creating)
neighbor timers
To set the timers for a specific BGP peer or peer group, use the neighbor timers router configuration command. 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 holdtimeSyntax Description
Default
keepalive: 60 seconds
holdtime: 180 secondsCommand Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 12.0
The timers configured for a specific neighbor or peer group override the timers configured for all BGP neighbors using the command timers bgp.
Example
The following example changes the keepalive timer to 70 seconds and the holdtime timer to 210 seconds for the BGP peer 192.98.47.0:
router bgp 109
neighbor 192.98.47.0 timers 70 210Related Commands
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clear ip bgp peer-group
router bgp
show ip bgp
timers bgpneighbor update-source
To have the Cisco IOS software allow internal BGP sessions to use any operational interface for TCP connections, use the neighbor update-source router configuration command. 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
no neighbor {ip-address | peer-group-name} update-source interfaceSyntax Description
ip-address
IP address of the BGP-speaking neighbor.
peer-group-name
Name of a BGP peer group.
interface
Loopback interface.
Default
Best local address
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This feature works in conjunction with the loopback interface feature described in the "Configuring Serial Interfaces" chapter of the Configuration Fundamentals 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.
Example
In the following example, BGP TCP connections for the specified neighbor will be sourced with loopback interface's IP address rather than the best local address:
router bgp 110network 160.89.0.0neighbor 160.89.2.3 remote-as 110 neighbor 160.89.2.3 update-source Loopback0Related Commands
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neighbor peer-group (creating)
neighbor version
To configure the Cisco IOS software to accept only a particular BGP version, use the neighbor version router configuration command. To use the default version level of a neighbor, use the no form of this command.
neighbor {ip-address | peer-group-name} version value
no neighbor {ip-address | peer-group-name} version valueSyntax Description
Default
BGP Version 4
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Entering this command disables dynamic version negotiation.
Our implementation of BGP supports BGP Versions 2, 3, and 4. If the neighbor does not accept default Version 4, dynamic version negotiation is implemented to negotiate 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.
Example
The following example locks down to Version 4 of the BGP protocol:
router bgp 109 neighbor 131.104.27.2 version 4Related Commands
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neighbor peer-group (creating)
neighbor weight
To assign a weight to a neighbor connection, use the neighbor weight router configuration command. To remove a weight assignment, use the no form of this command.
neighbor {ip-address | peer-group-name} weight weight
no neighbor {ip-address | peer-group-name} weight weightSyntax Description
ip-address
Neighbor's IP address.
peer-group-name
Name of a BGP peer group.
weight
Weight to assign. Acceptable values are 0 to 65535.
Default
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 Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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 match as-path and set weight route-map commands override the weights assigned using the neighbor weight and neighbor filter-list commands.
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.
Example
The following example sets the weight of all routes learned via 151.23.12.1 to 50:
router bgp 109 neighbor 151.23.12.1 weight 50Related Commands
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neighbor distribute-list
neighbor filter-list
neighbor peer-group (creating)network (BGP)
To specify the list of networks for the BGP routing process, use this form of the network router configuration command. To remove an entry, use the no form of this command.
network network-number [mask network-mask]
no network network-number [mask network-mask]Syntax Description
network-number
Network that BGP will advertise.
mask
Network or subnetwork mask.
network-mask
(Optional) Network mask address.
Default
No networks are specified.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
These types of networks can be learned from connected routes, dynamic routing, and from static route sources.
A maximum of 200 network commands may be specified for a single BGP process.
Example
The following example sets up network 131.108.0.0 to be included in the BGP updates:
router bgp 120network 131.108.0.0Related Commands
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network backdoor
network mask
network weight
router bgpnetwork backdoor
To specify a backdoor route to a BGP border router that will provide better information about the network, use the network backdoor router configuration command. To remove an address from the list, use the no form of this command.
network address backdoor
no network address backdoorSyntax Description
Default
No network is advertised.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
A backdoor network is treated as a local network, except that it is not advertised.
Example
The following example configures network 131.108.0.0 as a local network and network 192.31.7.0 as a backdoor network:
router bgp 109network 131.108.0.0network 192.31.7.0 backdoornetwork weight
To assign an absolute weight to a BGP network, use the network weight router configuration command. To delete an entry, use the no form of the command.
network address mask weight weight [route-map map-name]
no network address mask weight weight [route-map map-name]Syntax Description
address
IP address of the network.
mask
Network mask of the network.
weight
Absolute weight, or importance. It can be an integer from 0 to 65535.
route-map map-name
(Optional) Name of route-map.
Default
Weight is unmodified. Weight is zero if the original default weight has not been modified by other router configuration commands.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The weight specified by this command overrides a weight assigned by the redistribute command.
Example
In the following example, the BGP network has a weight of 100:
router bgp 5network 193.0.0.0 255.0.0.0 weight 100router bgp
To configure the Border Gateway Protocol (BGP) routing process, use the router bgp global configuration command. To remove a routing process, use the no form of this command.
router bgp autonomous-system
no router bgp autonomous-systemSyntax Description
autonomous-system
Number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along.
Default
No BGP routing process is enabled by default.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This command allows you to set up a distributed routing core that automatically guarantees the loop-free exchange of routing information between autonomous systems.
Example
The following example configures a BGP process for autonomous system 120:
router bgp 120Related Commands
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set as-path
To modify an autonomous system path for BGP routes, use the set as-path route map configuration command. To not modify the autonomous system path, use the no form of this command.
set as-path {tag | prepend as-path-string}
no set as-path {tag | prepend as-path-string}Syntax Description
Default
Autonomous system path is not modified.
Command Mode
Route map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
The only global BGP metric available to influence the best path selection is the AS-PATH length. By varying the length of the AS-PATH, a BGP speaker can influence the best path selection by a peer further away.
By allowing you to convert the tag into an autonomous system path, the set as-path tag variation of this command modifies the autonomous system length. The set as-path prepend variation allows you to "prepend" an arbitrary autonomous system path string to BGP routes. Usually the local autonomous system number is prepended multiple times. This increases the autonomous system path length.
Examples
The following example converts the tag of a redistributed route into an autonomous system path:
route-map set-as-path-from-tagmatch as-path 2set as-path prepend 100 100 100!router bgp 100redistribute ospf 109 route-map se t-as-path-from-tagThe following example prepends 100 100 100 to all the routes advertised to 131.108.1.1:
route-map set-as-pathmatch as-path 1set as-path prepend 100 100 100!router bgp 100neighbor 131.108.1.1 route-map set-as-path outRelated Commands
You can use the master indexes or search online to find documentation of related commands.
match as-path
match community-list
match interface
match ip address
match ip next-hop
match ip route-source
match metric
match route-type
match tag
route-map
set automatic-tag
set community
set level
set local-preference
set metric
set metric-type
set next-hop
set origin
set tag
set weightset community
To set the BGP COMMUNITIES attribute, use the set community route-map configuration command. To delete the entry, use the no form of this command.
set community {community-number [additive]} | none
no set community {community-number [additive]} | noneSyntax Description
Default
No BGP COMMUNITIES attributes exist.
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
You must have a match clause (even if it points to a "permit everything" list) if you want to set tags.
Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.
The set route-map configuration commands specify the redistribution set actions to be performed when all of a route map's match criteria are met. When all match criteria are met, all set actions are performed.
Example
In the following example, routes that pass the autonomous system path access list 1 have the community set to 109. Routes that pass the autonomous system path access list 2 have the community set to no-export (these routes will not be advertised to any EBGP peers).
route-map set_community 10 permitmatch as-path 1set community 109route-map set_community 20 permitmatch as-path 2set community no-exportRelated Commands
You can use the master indexes or search online to find documentation of related commands.
match community-list
route-mapset dampening
To set the BGP route dampening factors, use the set dampening route-map configuration command. To disable this function, use the no form of this command.
set dampening half-life reuse suppress max-suppress-time
no set dampeningSyntax Description
Default
Disabled
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
You must have a match clause (even if it points to a "permit everything" list) if you want to set tags.
Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.
The set route-map configuration commands specify the redistribution set actions to be performed when all of a route map's match criteria are met. When all match criteria are met, all set actions are performed.
When a BGP peer is reset, the route is withdrawn and the flap statistics cleared. In this instance, the withdrawal does not incur a penalty, even though route flap dampening is enabled.
Example
The following example sets the half-life to 30 minutes, the reuse value to 1500, the suppress value to 10000; and the maximum suppress time to 120 minutes:
route-map tagmatch as path 10set dampening 30 1500 10000 120!router bgp 100neighbor 171.69.233.52 route-map tag inRelated Commands
You can use the master indexes or search online to find documentation of related commands.
match as-path
match community-list
match interface
match ip address
match ip next-hop
match ip route-source
match metric
match route-type
match tag
route-map
set as-path
set automatic-tag
set community
set level
set local-preference
set metric
set metric-type
set next-hop
set origin
set tag
set weight
show route-mapset metric-type internal
To set the MED value on prefixes advertised to EBGP neighbors to match the IGP metric of the next hop, use the set metric internal route-map configuration command. To return to the default, use the no form of this command.
set metric-type internal
no set metric-type internalSyntax Description
This command has not arguments or keywords.
Default
Disabled
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
This command will cause BGP to advertise a MED that corresponds to the IGP metric associated with the NEXT HOP of the route. This command applies to generated, iBGP-, and eBGP-derived routes.
If this command is used, multiple BGP speakers in a common AS can advertise different MEDs for a particular prefix. Also, note that if the IGP metric changes, BGP will not readvertise the route.
You must have a match clause (even if it points to a "permit everything" list) if you want to set tags.
Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.
The set route-map configuration commands specify the redistribution set actions to be performed when all of a route map's match criteria are met. When all match criteria are met, all set actions are performed.
Example
In the following example, the MED for all the advertised routes to neighbor 160.89.2.3 is set to the corresponding IGP metric of the nexthop:
router bgp 109network 160.89.0.0neighbor 160.89.2.3 remote-as 200neighbor 160.89.2.3 route-map setMED out!route-map setMED permit 10match as-path 1set metric-type internal!ip as-path access-list 1 permit .*Related Commands
You can use the master indexes or search online to find documentation of related commands.
route-map
set origin
To set the BGP origin code, use the set origin route-map configuration command. To delete an entry, use the no form of this command.
set origin {igp | egp autonomous-system | incomplete}
Syntax Description
igp
Remote IGP.
egp
Local EGP.
autonomous-system
Remote autonomous system. This is an integer from 0 to 65535.
incomplete
Unknown heritage.
Default
Default origin, based on route in main IP routing table.
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You must have a match clause (even if it points to a "permit everything" list) if you want to set tags.
Use the route-map global configuration command with match and set route-map configuration commands to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.
The set route-map configuration commands specify the redistribution set actions to be performed when all of a route map's match criteria are met. When all match criteria are met, all set actions are performed.
Example
In the following example, routes that pass the route map have the origin set to IGP:
route-map set_originmatch as-path 10set origin igpRelated Commands
You can use the master indexes or search online to find documentation of related commands.
match as-path
match community-list
match interface
match ip address
match ip next-hop
match ip route-source
match metric
match route-type
match tag
route-map
set as-path
set automatic tag
set community
set level
set local-preference
set metric
set metric-type
set next-hop
set tag
set weightset weight
To specify the BGP weight for the routing table, use the set weight route-map configuration command. To delete an entry, use the no form of this command.
set weight weight
no set weight weightSyntax Description
Default
The weight is not changed by the specified route map.
Command Mode
Route-map configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You must have a match clause (even if it points to a "permit everything" list) if you want to set tags.
The implemented weight is based on the first matched autonomous system path. Weights indicated when an autonomous system path is matched override the weights assigned by global neighbor commands. In other words, the weights assigned with the match as-path and set weight route-map commands override the weights assigned using the neighbor weight and neighbor filter-list commands.
Example
In the following example, the BGP weight for the routes matching the autonomous system path access list is set to 200:
route-map set-weightmatch as-path 10set weight 200Related Commands
You can use the master indexes or search online to find documentation of related commands.
match as-path
match community-list
match interface
match ip address
match ip next-hop
match ip route-source
match metric
match route-type
match tag
route-map
set as-path
set automatic-tag
set community
set level
set local-preference
set metric
set metric-type
set next-hop
set origin
set tagshow ip bgp
To display entries in the BGP routing table, use the show ip bgp EXEC command.
show ip bgp [network] [network-mask] [longer-prefixes]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Displays
The following is sample output from the show ip bgp command:
Router# show ip bgpBGP table version is 716977, local router ID is 193.0.32.1Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path* i3.0.0.0 193.0.22.1 0 100 0 1800 1239 ?*>i 193.0.16.1 0 100 0 1800 1239 ?* i6.0.0.0 193.0.22.1 0 100 0 1800 690 568 ?*>i 193.0.16.1 0 100 0 1800 690 568 ?* i7.0.0.0 193.0.22.1 0 100 0 1800 701 35 ?*>i 193.0.16.1 0 100 0 1800 701 35 ?* 198.92.72.24 0 1878 704 701 35 ?* i8.0.0.0 193.0.22.1 0 100 0 1800 690 560 ?*>i 193.0.16.1 0 100 0 1800 690 560 ?* 198.92.72.24 0 1878 704 701 560 ?* i13.0.0.0 193.0.22.1 0 100 0 1800 690 200 ?*>i 193.0.16.1 0 100 0 1800 690 200 ?* 198.92.72.24 0 1878 704 701 200 ?* i15.0.0.0 193.0.22.1 0 100 0 1800 174 ?*>i 193.0.16.1 0 100 0 1800 174 ?* i16.0.0.0 193.0.22.1 0 100 0 1800 701 i*>i 193.0.16.1 0 100 0 1800 701 i* 198.92.72.24 0 1878 704 701 idescribes significant fields shown in the display.
The following is sample output from the show ip bgp command when you specify longer-prefixes:
Router# show ip bgp 198.92.0.0 255.255.0.0 longer-prefixesBGP table version is 1738, local router ID is 198.92.72.24Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 198.92.0.0 198.92.72.30 8896 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.1.0 198.92.72.30 8796 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.11.0 198.92.72.30 42482 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.14.0 198.92.72.30 8796 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.15.0 198.92.72.30 8696 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.16.0 198.92.72.30 1400 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.17.0 198.92.72.30 1400 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.18.0 198.92.72.30 8876 32768 ?* 198.92.72.30 0 109 108 ?*> 198.92.19.0 198.92.72.30 8876 32768 ?* 198.92.72.30 0 109 108 ?show ip bgp cidr-only
To display routes with nonnatural network masks (that is, classless interdomain routing, or CIDR), use the show ip bgp cidr-only privileged EXEC command.
show ip bgp cidr-only
Syntax Description
This command has no arguments or keywords.
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip bgp cidr-only command:
Router# show ip bgp cidr-onlyBGP table version is 220, local router ID is 198.92.73.131Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 192.0.0.0/8 198.92.72.24 0 1878 ?*> 198.92.0.0/16 198.92.72.30 0 108 ?describes significant fields shown in the display.
show ip bgp community
To display routes that belong to specified BGP communities, use the show ip bgp community EXEC command.
show ip bgp community community-number [exact]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Sample Display
The following is sample output from the show ip bgp community command:
router# show ip bgp community 111:12345 internetBGP table version is 10, local router ID is 224.0.0.10Status codes: s suppressed, d damped, h history, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 2.2.2.2/32 158.43.222.2 0 0 222 ?*> 111.0.0.0 158.43.222.2 0 0 222 ?*> 158.43.0.0 158.43.222.2 0 0 222 ?*> 158.43.44.44/32 158.43.222.2 0 0 222 ?* 158.43.222.0/24 158.43.222.2 0 0 222 i*> 172.17.240.0/21 158.43.222.2 0 0 222 ?*> 192.168.212.0 158.43.222.2 0 0 222 i*> 203.9.1.0 158.43.222.2 0 0 222 ?describes significant fields shown in the display.
show ip bgp community-list
To display routes that are permitted by the BGP community list, use the show ip bgp community-list EXEC command.
show ip bgp community-list community-list-number [exact]
Syntax Description
community-list-number
Community list number in the range 1 to 99.
exact
(Optional) Displays only routes that have an exact match.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Sample Display
The following is sample output of the show ip bgp community-list command:
Router# show ip bgp community-list 20BGP table version is 716977, local router ID is 193.0.32.1Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path* i3.0.0.0 193.0.22.1 0 100 0 1800 1239 ?*>i 193.0.16.1 0 100 0 1800 1239 ?* i6.0.0.0 193.0.22.1 0 100 0 1800 690 568 ?*>i 193.0.16.1 0 100 0 1800 690 568 ?* i7.0.0.0 193.0.22.1 0 100 0 1800 701 35 ?*>i 193.0.16.1 0 100 0 1800 701 35 ?* 198.92.72.24 0 1878 704 701 35 ?* i8.0.0.0 193.0.22.1 0 100 0 1800 690 560 ?*>i 193.0.16.1 0 100 0 1800 690 560 ?* 198.92.72.24 0 1878 704 701 560 ?* i13.0.0.0 193.0.22.1 0 100 0 1800 690 200 ?*>i 193.0.16.1 0 100 0 1800 690 200 ?* 198.92.72.24 0 1878 704 701 200 ?* i15.0.0.0 193.0.22.1 0 100 0 1800 174 ?*>i 193.0.16.1 0 100 0 1800 174 ?* i16.0.0.0 193.0.22.1 0 100 0 1800 701 i*>i 193.0.16.1 0 100 0 1800 701 i* 198.92.72.24 0 1878 704 701 idescribes significant fields shown in the display.
show ip bgp dampened-paths
To display BGP dampened routes, use the show ip bgp dampened-paths EXEC command.
show ip bgp dampened-paths
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Sample Display
The following is sample output from the show ip bgp dampened-paths command:
Router# show ip bgp dampened-pathsBGP table version is 10, local router ID is 171.69.232.182Status codes: s suppressed, d damped, h history, * valid, > best, i -internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork From Reuse Path*d 10.0.0.0 171.69.232.177 00:18:4 100 ?*d 12.0.0.0 171.69.232.177 00:28:5 100 ?describes the fields in the display.
Related Commands
You can use the master indexes or search online to find documentation of related commands.
bgp dampening
clear ip bgp dampeningshow ip bgp filter-list
To display routes that conform to a specified filter list, use the show ip bgp filter-list privileged EXEC command.
show ip bgp filter-list access-list-number
Syntax Description
access-list-number
Number of an autonomous system path access list. It can be a number from 1 to 199.
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip bgp filter-list command:
Router# show ip bgp filter-list 2BGP table version is 1738, local router ID is 198.92.72.24Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path* 198.92.0.0 198.92.72.30 0 109 108 ?* 198.92.1.0 198.92.72.30 0 109 108 ?* 198.92.11.0 198.92.72.30 0 109 108 ?* 198.92.14.0 198.92.72.30 0 109 108 ?* 198.92.15.0 198.92.72.30 0 109 108 ?* 198.92.16.0 198.92.72.30 0 109 108 ?* 198.92.17.0 198.92.72.30 0 109 108 ?* 198.92.18.0 198.92.72.30 0 109 108 ?* 198.92.19.0 198.92.72.30 0 109 108 ?* 198.92.24.0 198.92.72.30 0 109 108 ?* 198.92.29.0 198.92.72.30 0 109 108 ?* 198.92.30.0 198.92.72.30 0 109 108 ?* 198.92.33.0 198.92.72.30 0 109 108 ?* 198.92.35.0 198.92.72.30 0 109 108 ?* 198.92.36.0 198.92.72.30 0 109 108 ?* 198.92.37.0 198.92.72.30 0 109 108 ?* 198.92.38.0 198.92.72.30 0 109 108 ?* 198.92.39.0 198.92.72.30 0 109 108 ?describes significant fields shown in the display.
show ip bgp flap-statistics
To display BGP flap statistics, use the show ip bgp flap-statistics EXEC command.
show ip bgp flap-statistics [{regexp regexp} | {filter-list list} | {address mask [longer-prefix]}]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
If no arguments or keywords are specified, the router displays flap statistics for all routes.
Sample Display
The following is sample output from the show ip bgp flap-statistics command:
Router# show ip bgp flap-statisticsBGP table version is 10, local router ID is 171.69.232.182Status codes: s suppressed, d damped, h history, * valid, > best, i -internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork From Flaps Duration Reuse Path*d 10.0.0.0 171.69.232.177 4 00:13:31 00:18:10 100*d 12.0.0.0 171.69.232.177 4 00:02:45 00:28:20 100describes the significant fields in the display.
Related Commands
You can use the master indexes or search online to find documentation of related commands.
bgp dampening
clear ip bgp flap-statisticsshow ip bgp inconsistent-as
To display routes with inconsistent originating autonomous systems, use the show ip bgp inconsistent-as privileged EXEC command.
show ip bgp inconsistent-as
Syntax Description
This command has no arguments or keywords.
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Sample Display
The following is sample output from the show ip bgp inconsistent-as command:
Router# show ip bgp inconsistent-asBGP table version is 87, local router ID is 172.19.82.53Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path* 11.0.0.0 171.69.232.55 0 0 300 88 90 99 ?*> 171.69.232.52 2222 0 400 ?* 171.69.0.0 171.69.232.55 0 0 300 90 99 88 200 ?*> 171.69.232.52 2222 0 400 ?* 200.200.199.0 171.69.232.55 0 0 300 88 90 99 ?*> 171.69.232.52 2222 0 400 ?show ip bgp neighbors
To display information about the TCP and BGP connections to neighbors, use the show ip bgp neighbors EXEC command.
show ip bgp neighbors [address] [received-routes | routes | advertised-routes | {paths
regular-expression} | dampened-routes]Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The received-routes keyword first appeared in Cisco IOS Release 11.2.
Sample Displays
The following is sample output from the show ip bgp neighbors command:
Router# show ip bgp neighbors 171.69.232.178BGP neighbor is 171.69.232.178, remote AS 10, external linkIndex 1, Offset 0, Mask 0x2Inbound soft reconfiguration allowedBGP version 4, remote router ID 171.69.232.178BGP state = Established, table version = 27, up for 00:06:12Last read 00:00:12, hold time is 180, keepalive interval is 60 secondsMinimum time between advertisement runs is 30 secondsReceived 19 messages, 0 notifications, 0 in queueSent 17 messages, 0 notifications, 0 in queueInbound path policy configuredRoute map for incoming advertisements is testingConnections established 2; dropped 1Connection state is ESTAB, I/O status: 1, unread input bytes: 0Local host: 171.69.232.181, Local port: 11002Foreign host: 171.69.232.178, Foreign port: 179Enqueued packets for retransmit: 0, input: 0, saved: 0Event Timers (current time is 0x530C294):Timer Starts Wakeups NextRetrans 12 0 0x0TimeWait 0 0 0x0AckHold 12 10 0x0SendWnd 0 0 0x0KeepAlive 0 0 0x0GiveUp 0 0 0x0PmtuAger 0 0 0x0iss: 133981889 snduna: 133982166 sndnxt: 133982166 sndwnd: 16108irs: 3317025518 rcvnxt: 3317025810 rcvwnd: 16093 delrcvwnd: 291SRTT: 441 ms, RTTO: 2784 ms, RTV: 951 ms, KRTT: 0 msminRTT: 0 ms, maxRTT: 300 ms, ACK hold: 300 msFlags: higher precedence, nagleDatagrams (max data segment is 1460 bytes):Rcvd: 15 (out of order: 0), with data: 12, total data bytes: 291Sent: 23 (retransmit: 0), with data: 11, total data bytes: 276describes the fields shown in the display.
The following is sample output from the show ip bgp neighbors command with advertised-routes:
Router# show ip bgp neighbors 171.69.232.178 advertised-routesBGP table version is 27, local router ID is 171.69.232.181Status codes: s suppressed, d damped, h history, * valid, > best, i -internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*>i110.0.0.0 171.69.232.179 0 100 0 ?*> 200.2.2.0 0.0.0.0 0 32768 iThe following is sample output from the show ip bgp neighbors command with routes:
Router# show ip bgp neighbors 171.69.232.178 routesBGP table version is 27, local router ID is 171.69.232.181Status codes: s suppressed, d damped, h history, * valid, > best, i -internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 10.0.0.0 171.69.232.178 40 0 10 ?*> 20.0.0.0 171.69.232.178 40 0 10 ?describes the fields shown in the display.
The following is sample output from the show ip bgp neighbors command with paths:
Router# show ip bgp neighbors 171.69.232.178 paths ^10Address Refcount Metric Path0x60E577B0 2 40 10 ?show ip bgp paths
To display all the BGP paths in the database, use the show ip bgp paths EXEC command.
show ip bgp paths
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip bgp paths command:
Router# show ip bgp pathsAddress Hash Refcount Metric Path0x60E5742C 0 1 0 i0x60E3D7AC 2 1 0 ?0x60E5C6C0 11 3 0 10 ?0x60E577B0 35 2 40 10 ?describes significant fields shown in the display.
show ip bgp peer-group
To display information about BGP peer groups, use the show ip bgp peer-group EXEC command.
show ip bgp peer-group [tag] [summary]
Syntax Description
tag
(Optional) Displays information about that specific peer group.
summary
(Optional) Displays a summary of the status of all the members of a peer group.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Sample Display
The following is sample output from the show ip bgp peer-group command:
Router# show ip bgp peer-group0 internalBGP neighbor is internal, peer-group leaderBGP version 4Minimum time between advertisement runs is 5 secondsIncoming update AS path filter list is 2Outgoing update AS path filter list is 1Route map for outgoing advertisements is set-medshow ip bgp regexp
To display routes matching the regular expression, use the show ip bgp regexp privileged EXEC command.
show ip bgp regexp regular-expression
Syntax Description
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
Router# show ip bgp regexp 108$BGP table version is 1738, local router ID is 198.92.72.24Status codes: s suppressed, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path* 198.92.0.0 198.92.72.30 0 109 108 ?* 198.92.1.0 198.92.72.30 0 109 108 ?* 198.92.11.0 198.92.72.30 0 109 108 ?* 198.92.14.0 198.92.72.30 0 109 108 ?* 198.92.15.0 198.92.72.30 0 109 108 ?* 198.92.16.0 198.92.72.30 0 109 108 ?* 198.92.17.0 198.92.72.30 0 109 108 ?* 198.92.18.0 198.92.72.30 0 109 108 ?* 198.92.19.0 198.92.72.30 0 109 108 ?* 198.92.24.0 198.92.72.30 0 109 108 ?* 198.92.29.0 198.92.72.30 0 109 108 ?* 198.92.30.0 198.92.72.30 0 109 108 ?* 198.92.33.0 198.92.72.30 0 109 108 ?* 198.92.35.0 198.92.72.30 0 109 108 ?* 198.92.36.0 198.92.72.30 0 109 108 ?* 198.92.37.0 198.92.72.30 0 109 108 ?* 198.92.38.0 198.92.72.30 0 109 108 ?* 198.92.39.0 198.92.72.30 0 109 108 ?show ip bgp summary
To display the status of all BGP connections, use the show ip bgp summary EXEC command.
show ip bgp summary
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip bgp summary command:
Router# show ip bgp summaryBGP table version is 717029, main routing table version 71702919073 network entries (37544 paths) using 3542756 bytes of memory691 BGP path attribute entries using 57200 bytes of memoryNeighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State193.0.16.1 4 1755 32642 2973 717029 0 0 1:27:11193.0.17.1 4 1755 4790 2973 717029 0 0 1:27:51193.0.18.1 4 1755 7722 3024 717029 0 0 1:28:13193.0.19.1 4 1755 0 0 0 0 0 2d02 Active193.0.20.1 4 1755 3673 3049 717029 0 0 2:50:10193.0.21.1 4 1755 3741 3048 717029 0 0 12:24:43193.0.22.1 4 1755 33129 3051 717029 0 0 12:24:48193.0.23.1 4 1755 0 0 0 0 0 2d02 Active193.0.24.1 4 1755 0 0 0 0 0 2d02 Active193.0.25.1 4 1755 0 0 0 0 0 2d02 Active193.0.26.1 4 1755 0 0 0 0 0 2d02 Active193.0.27.1 4 1755 4269 3049 717029 0 0 12:39:33193.0.28.1 4 1755 3037 3050 717029 0 0 2:08:15198.92.72.24 4 1878 11635 13300 717028 0 0 0:50:39describes significant fields shown in the display.
synchronization
To enable the synchronization between BGP and your IGP, use the synchronization router configuration command. To enable the Cisco IOS software to advertise a network route without waiting for the IGP, use the no form of this command.
synchronization
no synchronizationSyntax Description
This command has no arguments or keywords.
Default
Enabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Usually, a BGP speaker does not advertise a route to an external neighbor unless that route is local or exists in the IGP. The no synchronization command allows the Cisco IOS software to advertise a network route without waiting for the IGP. This feature allows routers and access servers within an autonomous system to have the route before BGP makes it available to other autonomous systems.
Use synchronization if there are routers in the autonomous system that do not speak BGP.
Example
The following example enables a router to advertise a network route without waiting for the IGP:
router bgp 120no synchronizationtable-map
To modify metric and tag values when the IP routing table is updated with BGP learned routes, use the table-map router configuration command. To disable this function, use the no form of the command.
table-map route-map-name
no table-map route-map-nameSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This command adds the route-map name defined by the route-map command to the IP routing table. This command is used to set the tag name and the route metric to implement redistribution.
You can use match clauses of route maps in the table-map command. IP access list, autonomous system paths, and next-hop match clauses are supported.
Example
In the following example, the Cisco IOS software is configured to automatically compute the tag value for the BGP learned routes and to update the IP routing table.
route-map tagmatch as path 10set automatic-tag!router bgp 100table-map tagRelated Commands
You can use the master indexes or search online to find documentation of related commands.
match as-path
match ip address
match ip next-hop
route-maptimers bgp
To adjust BGP network timers, use the timers bgp router configuration command. To reset the BGP timing defaults, use the no form of this command.
timers bgp keepalive holdtime
no timers bgpSyntax Description
Defaults
keepalive: 60 seconds
holdtime: 180 secondsCommand Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Example
The following example changes the keepalive timer to 70 seconds and the holdtime timer to 210 seconds:
timers bgp 70 210Related Commands
You can use the master indexes or search online to find documentation of related commands.
clear ip bgp peer-group
router bgp
show ip bgp
