06-18-2008 12:00 AM - edited 03-03-2019 10:23 PM
Hello!
We have 2 sites with 7500 Routers and BGP
We own a /19 Network
Our Upstream Provider wants me now for load reduction to accept 2 times the same network 1.2.3.4/19 on both sites.
I should then enter the "real" networks on the routers via "more specific" routes.
1 want 1 /24 network to terminate on site 1 the rest on site 2
I have no idea what my upstream provider means..
http://www.cisco.com/en/US/docs/ios/12_0/np1/configuration/guide/1cbgp.html#wp8238
thanks!
marco
06-18-2008 12:09 AM
It's often useful to conditionally advertise some routes to upstream neighbors-
particularly if you are trying to control which link is crossed by traffic destined to a
particular network.BGP has the capability to conditionally advertise routes;
As per me you can use if the one link down automatically the /24 will be announced by the second pair. For this you can use the given command
neighbor x.x.x.x advertise-map toadvertise non-exist-map ifnotexist
access-list 10 permit 172.28.23.0 0.0.0.255
access-list 10 permit 172.28.23.0 0.0.0.255
access-list 20 deny 10.1.3.0 0.0.0.255
access-list 20 permit any
access-list 30 permit 10.1.3.0 0.0.0.255
â¦.
route-map ifnotexist permit 10
match ip address 30
!
route-map ifnotexist deny 20
!
route-map toadvertise permit 10
match ip address 10
regards
shivlu
06-18-2008 12:35 AM
so i can advertise my /24er routes upstream so only the nets i want will terminate on sitea and siteb?
06-18-2008 12:44 AM
you can advertise the /24 by one end and with the conf given the seocnd link will chk will the first goes down then it willl be advertise bty the other end.
regards
shivlu
06-18-2008 04:49 AM
Well i dont want a fallback.. it should be only static.
:-)
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