Sunday, July 26, 2020

Using BGP communities from upstreams of my upstreams

I want to tweak one of our prefixes to get inbound traffic flowing through some lower latency routes, but none of our two direct upstreams have BGP communities to drop or prepend announces to any of their upstreams and haven't show any interest in implementing it.

Example: our two upstreams has CenturyLink among of their upstreams, but one of them connects to it at a far location which leads to greater latency to most of destinations. I tried appending CenturyLink's LocalPref 70 community (3356:70) when announcing prefix to this upstream, expecting CenturyLink would choose the other path with default LocalPref 100, but it didn't work according to their Looking Glass. I can't just drop announcing the prefix to this upstream because they are better for routes that doesn't go through CenturyLink.

Was it supposed to work? Is there any other way? I don't think CenturyLink and other major upstreams would get a multihop BGP session with us so we could use their communities, would they?



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