Cooperative Route Filtering

If a BGP speaker negotiates the cooperative route filtering capability with a peer, then the speaker can transfer inbound route filters to the peer. The peer then installs the filter as an outbound route filter (ORF) on the remote end. The ORF is applied by the peer after application of its configured outbound policies. This cooperative filtering has the advantage of both reducing the amount of processing required for inbound BGP updates and reducing the amount of BGP control traffic generated by BGP updates.

clear ip bgp

• Use to push an ORF to the peer and reapply inbound policy to all received routes without clearing the BGP session.
• You can specify the IP address of a BGP neighbor, the name of a BGP peer group, or an address family to be cleared.
• Use the asterisk (*) to clear all BGP connections.
• If the ORF capability is not configured or received on the peer, then the prefix-filter keyword is ignored and the router performs a normal inbound soft reconfiguration.
• This command takes effect immediately.
• There is no no version.
• See clear ip bgp.

neighbor capability

• Use to negotiate the exchange of inbound route filters and their installation as ORFs by specifying the orf keyword, an ORF type, and the direction of the capability.
• If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command unless it is overridden for a specific peer.
• You cannot configure the receive direction for the orf capability for a peer that is a member of a peer group or for a peer.
• When issued with the orf keyword, this command takes effect immediately and automatically bounces the BGP session.
• Example

  host1(config-router)#neighbor 192.168.1.158 capability orf prefix-list both

• Use the no version to prevent advertisement of the capability. Use the default version to restore the default, advertising the capability.
• See neighbor capability.

neighbor maximum-orf-entries

• Use to set the maximum number of ORF entries of any one type that will be accepted from the specified neighbor.
• Example

  host1(config-router)#neighbor 192.168.1.158 maximum-orf-entries 125000

• Use the no version to restore the default value of no limits.
• See neighbor maximum-orf-entries.

neighbor prefix-list

• Use to assign an inbound or outbound prefix list.
• If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command unless it is overridden for a specific peer. However, you cannot configure a member of a peer group to override the inherited peer group characteristic for outbound policy.
• Example

  host1(config-router)#neighbor 192.168.1.158 prefix-list seoul19 in

• New policy values are applied to all routes that are sent (outbound policy) or received (inbound policy) after you issue the command.

  To apply the new policy to routes that are already present in the BGP routing table, you must use the clear ip bgp command to perform a soft clear or hard clear of the current BGP session.

  Behavior is different for outbound policies configured for peer groups for which you have enabled Adj-RIBs-Out. If you change the outbound policy for such a peer group and want to fill the Adj-RIBs-Out table for that peer group with the results of the new policy, you must use the clear ip bgp peer-group command to perform a hard clear or outbound soft clear of the peer group. You cannot merely perform a hard clear or outbound soft clear for individual peer group members because that causes BGP to resend only the contents of the Adj-RIBs-Out table.

• Use the no version to remove the prefix list.
• See neighbor prefix-list.

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