Users Guide

When a BGP neighbor connection with authentication rejects a passive peer-template, the system prevents another passive
peer-template on the same subnet from connecting with the BGP neighbor. To work around this constraint, change the BGP
configuration or change the order of the peer template configuration.
You can restrict the number of passive sessions the neighbor accepts using the limit command.
1. Enable BGP and assign the AS number to the local BGP speaker in CONFIGURATION mode (1 to 65535 for 2-byte, 1 to
4294967295 for 4-byte).
router bgp as-number
2. Configure a template that does not initiate TCP connections with other peers in ROUTER-BGP mode. A maximum of 16
characters.
template template-name
3. Create and enter the AS number for the remote neighbor in ROUTER-BGP-TEMPLATE mode (1 to 4294967295).
remote-as as-number
4. Enable peer listening and enter the maximum dynamic peers count in ROUTER-BGP-TEMPLATE mode (1 to 4294967295).
listen neighbor ip-address limit
Only after the peer template responds to an OPEN message sent on the subnet does the state of its BGP change to
ESTABLISHED. After the peer template is ESTABLISHED, the peer template is the same as any other peer template, see Peer
templates.
If you do not configure a BGP device in Peer-Listening mode, a session with a dynamic peer comes up. Passwords are not
supported on BGPv4/v6 dynamic peers.
Configure passive peering
OS10(config)# router bgp 10
OS10(conf-router-bgp-10)# template bgppg
OS10(conf-router-template)# remote-as 100
OS10(conf-router-template)# listen 32.1.0.0/8 limit 10
Local AS
During BGP network migration, you can maintain existing AS numbers. Reconfigure your routers with the new information to
disable after the migration. Network migration is not supported on passive peer templates. You must configure Peer templates
before assigning it to an AS.
The following options are available with the local-as command:
To append the global-as and local-as in the outbound AS_PATH for the neighbor, use:
local-as as-number
To not add the local-as to prefixes received from the BGP neighbor, use:
local-as as-number no-prepend
To not add the global AS number in the outbound AS_PATH for that neighbor, use:
local-as as-number no-prepend replace-as
1. Enter a neighbor IP address, A.B.C.D, in ROUTER-BGP mode.
neighbor ip-address
2. Enter a local-as number for the peer, and the AS values not prepended to announcements from the neighbors in ROUTER-
NEIGHBOR mode (1 to 4294967295).
local-as as number [no prepend]
636
Layer 3