This blog was originally started to better help me understand the technologies in the CCIE R&S blueprint; after completing the R&S track I have decided to transition the blog into a technology blog.

CCIE #29033

This blog will continue to include questions, troubleshooting scenarios, and references to existing and new technologies but will grow to include a variety of different platforms and technologies. Currently I have created over 185 questions/answers in regards to the CCIE R&S track!! Note: answers are in the comment field or within "Read More" section.

You can also follow me on twitter @FE80CC1E


Thursday, April 22, 2010

Question 8

Why would you use the BGP listen command?

1 comments:

Packets Analyzed said...

Used when using BGP dynamic neighbors. BGP does not discover other BGP neighbors automatically. BGP can establish relationships dynamically using a subnet range defined in a peer group.

BGP Listen - is used to limit to number of dynamic neighbors that can form a relationship.

R1
router bgp 123
bgp listen limit 100 (limits the number to 100 dynamically learned neighbors)
bgp listen range 10.21.0.0/16 peer-group10 (Defines a subnet range)
bgp listen range 192.16.1.0/24 peer-group192
neighbor group10 peer-group
neighbor group10 remote-as 123
neighbor group192 peer-group
neighbor group 192 remote-as 223
address-family ipv4 unicast (creates IPv4 unicast address family)
neighbor group192 activate (activates the neighbor under IPv4)
neighbor group19 activate
end

R2

router bgp 123
neighbor 10.0.0.1 remote-as 123
end

R3

router bgp 223
neighbor 192.16.1.1 remote-as 123
end

Post a Comment