[c-nsp] aggregate-address with 2 neighbours

CiscoNSP List CiscoNSP_list at hotmail.com
Wed Sep 28 06:01:15 EDT 2016


Hi Everyone,


If we have a customer with 2 sites, that has there own /24 that they have split into 2 x /25's - Each site advertises its /25 to us (In a single VRF)...we then want to advertise the aggregate /24 to our upstreams....so, to achieve this we would need to use (under address-family ipv4 vrf foo) aggregate-address xxx.xxx.xxx.xxx 255.255.255.0 as-set summary only  (So customers AS is maintained, and the smaller prefixes are filtered from being re-advertised to upstream)....I haven't had a chance to lab this up, so Im not 100% sure of the behaviour of aggregate-address....when our PE receives one/both of the /25s via bgp, it aggregates them into the /24 - Im assuming(hoping), it also keeps the more specific prefix in bgp also (And in fib), so that routing for the /25s to the correct sites is maintained?


Cheers


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