NetworkTalk & BGP

A.7.c) Route-map and BGP Configuration with ISP-C

  1. Same as before, multi-session connectivity explanations are detailed on the following paragraph.
    Since the default BGP table used for outgoing/upload traffic, will be the one of ISP-B, we will tag ISP-C’s BGP table with LocalPref 90 (since it is the same router, we could have used the metric parameter).
    At the same time, incoming/download traffic will come back through ISP-B’s link as primary active one
  2. ISP-C’s Ebgp link will be set up as a passive link, for that we can use as-prepend or BGP communities options. For some reasons which are explained later, in the tutorial we will use BGP communities.

router bgp 1000
neighbor 30.30.30.127 remote-as 400
neighbor 30.30.30.127 description 3xSTM4-ISP-C
neighbor 30.30.30.127 ebgp-multihop 2
neighbor 30.30.30.127 update-source Loopback0
neighbor 30.30.30.127 version 4
address-family ipv4
neighbor 30.30.30.127 activate
neighbor 30.30.30.127 send-community both
neighbor 30.30.30.127 route-map AS-400-INCOMING in
neighbor 30.30.30.127 route-map AS-400-OUTGOING out

ip route 30.30.30.127 255.255.255.255 POS1/1/2 30.30.31.25 name Loopback-Peer-AS400
ip route 30.30.30.127 255.255.255.255 POS1/1/1 30.30.31.21 name Loopback-Peer-AS400
ip route 30.30.30.127 255.255.255.255 POS1/1/3 30.30.31.29 name Loopback-Peer-AS400

route-map AS-400-INCOMING permit 10
match as-path 3
set local preference 90

route-map AS-400-OUTGOING permit 20
match as-path 2
set community 400:70

ip as-path access-list 2 permit ^$
ip as-path access-list 3 permit ^400_

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