Reference Guide

• Allow this neighbor ID to use the AS path the specified number of times.
CONFIG-ROUTER-BGP mode
neighbor {IP address | peer-group-name} allowas-in number
– Peer Group Name: 16 characters.
– Number: 1 through 10.
Format: IP Address: A.B.C.D.
You must Configure Peer Groups before assigning it to an AS.
The lines shown in bold are the number of times ASN 65123 can appear in the AS path (allows–in 9).
To disable this feature, use the no neighbor allow-as in number command in CONFIGURATION ROUTER
BGP mode.
Example of Viewing AS Numbers in AS Paths
R2(conf-router_bgp)#show conf
!
router bgp 65123
bgp router-id 192.168.10.2
network 10.10.21.0/24
network 10.10.32.0/24
network 100.10.92.0/24
network 192.168.10.0/24
bgp four-octet-as-support
neighbor 10.10.21.1 remote-as 65123
neighbor 10.10.21.1 filter-list Laura in
neighbor 10.10.21.1 no shutdown
neighbor 10.10.32.3 remote-as 65123
neighbor 10.10.32.3 no shutdown
neighbor 100.10.92.9 remote-as 65192
neighbor 100.10.92.9 local-as 6500
neighbor 100.10.92.9 no shutdown
neighbor 192.168.10.1 remote-as 65123
neighbor 192.168.10.1 update-source Loopback 0
neighbor 192.168.10.1 no shutdown
neighbor 192.168.12.2 remote-as 65123
neighbor 192.168.12.2 allowas-in 9
neighbor 192.168.12.2 update-source Loopback 0
neighbor 192.168.12.2 no shutdown
R2(conf-router_bgp)#R2(conf-router_bgp)#
Enabling Graceful Restart
Use this feature to lessen the negative effects of a BGP restart.
FTOS advertises support for this feature to BGP neighbors through a capability advertisement. You can enable graceful
restart by router and/or by peer or peer group.
NOTE: By default, BGP graceful restart is disabled.
The default role for BGP is as a receiving or restarting peer. If you enable BGP, when a peer that supports graceful
restart resumes operating, FTOS performs the following tasks:
• Continues saving routes received from the peer if the peer advertised it had graceful restart capability.
Continues forwarding traffic to the peer.
• Flags routes from the peer as Stale and sets a timer to delete them if the peer does not perform a graceful
restart.
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