On 2021-04-29, Marko Cupać <marko.cu...@mimar.rs> wrote: > I guess this is not related to bgpd, but I hope there are skilled > network admins here who can give me advice. > > I have a problem with circular routing on a site which talks BGP with > two upstream providers, with traffic to site which has static default > route over third ISP: > > --> ISP1 --> ISP3 --> > SITEA SITEB > <-- ISP2 <-- ISP3 <--
Asymmetric routing (circular suggest that it's looping so you have no working connecticity, which I tuink ks not what you're describing). > I tried to prepend self / neighbor to ISP2 - no change (ISP1 has best > routes for 99% of the prefixes, including to SITEB). I contacted ISP2, > they said the problem is with ISP3. I contacted ISP3, they said ISP2 > announces my prefix (they're my LIR) so the best route is over them. I > contacted ISP2 again, they said they prepended my prefix to ISP3, but > situation is the same. > > Is it OK for ISP2 (my LIR) to announce and prepend my prefix? I thought > I should be in control of that. > > Is there anything I can do about the situation? You can't do much to control incoming traffic though you can sometimes influence it. But you do control which routes you accept/prefer. If you want to avoid the assymetric path, you need to prefer ISP2's announcwments for SITEB, for example you could match and give it a higher localpref. Is it causing a problem though? This is completely normal and expected on the internet. > Thank you in advance, >
