12-09-2010 06:39 AM - edited 03-04-2019 10:44 AM
Guys, hope you can help...
I've got a /23 LAN subnet which i need to route out to a carrier in different ways...
192.168.0.0/23 is the LAN Subnet but when it comes in on the HSRP active i need to tell that active router that if the traffic is from the first /24 in that range it should go to a next hop of the back to back so it will naturally egress out of that gateway (i've setup as prepends to make sure they route back the right way).
My question is if i have a /23 on the LAN do i have to define that as a /23 in my bgp network statement or x2 /24s? My prefix lists which is what i'm matching on for the prepending have to be set to /24s and i'm matching on the LAN with an ACL which is also 24s for the PBR.
Got no way to lab this at the moment so if anyone knows i'd appriciate it...
Rich
12-09-2010 12:44 PM
BGP will only put something in the bgp table (via the network statement) if that exact route already excist in the routing table.
So if its a /23 in the routing table then you need to do the network statement in BGP as a /23.
HTH
12-10-2010 02:05 AM
Ended up putting two /24 statics in and pointing them to the LAN, this then matches the prefix lists and gets advertised...
Thanks
Rich
12-10-2010 06:23 AM
another way is the "pull up routes"
ip route x.x.x.x 255.255.255.0 null0 254
this helps very much when configuring BGP
(this route will never used as long you have routes matching the same length with lower administrive distance, in your case you have this route "connected")
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