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How long does it take for BGP communities to propagate?
I removed telia by using a BGP community, and now I need it again. I removed the community which triple appended to telia, but it seems to be taking forever.
export filter {
#bgp_community = -empty-;
#bgp_community = add(bgp_community, (64602,1299));
accept;
};
When I comment out the prefix, it propagates in seconds, but its been an hour since I removed the community and it still refuses to go through telia again.
How long does this usually take?
Comments
It should be nearly instant -- maybe an hour or two.
1 or 2 hour seems like a long time if I need to temporarily avoid a bad carrier. But it is good to know that maybe I just have to wait another hour for it to take effect.
When I commented out my prefix route, everyone stopped routing to it within seconds though. I wonder why it can't be as instant as that.
How long was the BGP announcement removed for? If it was a while maybe you need to open a ticket for them to accept announcements from your ASN again.
I don't have an issue with the prefix announcement. I commented it out, everyone stopped routing to it within seconds, then put it back in, and everyone routed there again in seconds.
The problem I have is that my traffic isn't going through telia anymore after I removed the BGP community that appended 3x to telia. I've been waiting for almost 2 hours now, and everyone still seems to avoid telia when going to my IP.
If the prefix is accepted without the communities, it would simply mean that as-path didn’t change enough for the route to be changed m, or the routing policies at the other end dictate so.
Also, remember you can only influence inbound route.
You can check if the prefix has communities through Telia LG.
There’s no such thing like propagation of communities. Community describes a prefix and is an element of the route. Any changes you make “propagate” as quickly as announcement or withdrawal of such prefix.
Further, if you made many changes in a short period of time, some networks may have dampened the route as it was unstable. How long the route is dampened for will depend on individual policies of the networks penalising it.
@Clouvider covered it well.
With the exception of any dampening / anti-flapping measures it should be within a few RTT of your total route. So seconds.
In the real world there always is usually a degree of dampening somewhere so a minute is probably safe. Longer than that and theres either extreme dampening, or you need to investigate.