I have the following network. I want to prevent Subnet 2, S2, from being routed outbound of ISPA (preferring ISPC is also acceptable).
None of my ISPs use BGP communities. Given that this is a live network, I'm scared to be cavalier and use trial and error here. I think I might be able to do this with MED and the always-compare-med option, but I really don't know enough to be confident.
ISPA ISPB ISPC ISPD \ / \ / R1 -------- R2 | | S1 S2 S3 S3
This is with Arista (cisco-like) equipment. Using VRFs isn't a good option here.
I've just tried the following. The in/out pieces here are confusing me. Is this a valid way of assigning attributes to a particular subnet?
neighbor ISPC route-map COG-RM-IN in route-map COG-RM-IN permit 10 match ip address access-list COG-ACL-OUT set local-preference 110 ! ip access-list COG-ACL-OUT 10 permit ip S3/24 any !