Reference Guide

Border Gateway Protocol IPv4 (BGPv4) | 211
Configure passive peering
When you enable a peer-group, the software sends an OPEN message to initiate a TCP connection. If you
enable passive peering for the peer group, the software does not send an OPEN message, but it will
respond to an OPEN message.
When a BGP neighbor connection with authentication configured is rejected by a passive peer-group,
FTOS does not allow another passive peer-group on the same subnet to connect with the BGP neighbor. To
work around this, change the BGP configuration or change the order of the peer group configuration.
You can constrain the number of passive sessions accepted by the neighbor. The
limit keyword allows you
to set the total number of sessions the neighbor will accept, between 2 and 265. The default is 256 sessions.
Use these commands in the following sequence, starting in the CONFIGURATION ROUTER BGP mode
to configure passive peering.
Only after the peer group responds to an OPEN message sent on the subnet does its BGP state change to
ESTABLISHED. Once the peer group is ESTABLISHED, the peer group is the same as any other peer
group.
For more information on peer groups, refer to Configure Peer Groups.
Maintain existing AS numbers during an AS migration
The local-as feature smooths out the BGP network migration operation and allows you to maintain
existing ASNs during a BGP network migration.
Step Command Syntax Command Mode Purpose
1 neighbor peer-group-name
peer-group passive limit
CONFIG-ROUTER-
BGP
Configure a peer group that does not initiate TCP
connections with other peers. Enter the limit
keyword to restrict the number of sessions
accepted.
2
neighbor peer-group-name
subnet subnet-number mask
CONFIG-ROUTER-
BGP
Assign a subnet to the peer group. The peer
group will respond to OPEN messages sent on
this subnet.
3
neighbor peer-group-name no
shutdown
CONFIG-ROUTER-
BGP
Enable the peer group.
4
neighbor peer-group-name
remote-as as-number
CONFIG-ROUTER-
BGP
Create and specify a remote peer for BGP
neighbor.