Tuesday, January 29, 2008

BGP Peer Session Templates

BGP Essentials: Peer Session Templates
IOS releases 12.0S and 12.3T introduced peer templates, a scalable hierarchical way of configuring BGP session parameters and inbound/outbound policies. For example, to configure the session parameters for all your IBGP sessions, use the following session template:
router bgp 65001
template peer-session IBGP
remote-as 65001
description IBGP peers
password s3cr3t
update-source Loopback0
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123newft/123t/123t_4/gtbgpdpg.pdf

After the session template has been configured, adding a new IBGP peer takes just a single configuration command (two if you want to add neighbor description):

router bgp 65001
neighbor 10.0.1.2 inherit peer-session IBGP
neighbor 10.0.1.2 description R2


In Cisco IOS release 12.3T (integrated in 12.4), we've got an interesting (and quite understated) BGP feature: BGP peer-groups are no longer a performance feature (previously, IOS used them to reduce the time needed to compute outbound BGP updates). IOS now performs automatic grouping of BGP neighbors in dynamic update peer-groups (pdf) that receive identical BGP updates based on per-neighbor outbound parameters.

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