I have a problem with having uplinks to 2 providers which both have links to one provider that is the same. I am sending out the amount of traffic I would normally expect (adjusted via prepend) but my incoming traffic on the lower-quality link is getting hammered. What I am trying to accomplish is the same thing as a prepend so routes that are advertised have my ASN shown twice, or even 3 times, to eliminate the largest portion of traffic from coming in on that link.
Has anybody found a way to modify the publicly advertised route so that it will show the AS number using route filters or otherwise?
I dont understand the problem. Do you prepend only incoming Announcements and
not the outgoing? When you prepend outgoing traffic on the bad line it should work.
yes, you can use routing filters to prepend. Just specify the number of prepends you want. I am curious if the upstream upstream will merge the two or if each will show with a different as path.
I guess I should lay out the problem a little better. I have 2 providers that I am linked to. Both of these providers give me a 100MBps burstable connection, but one of them gives me better routes than the other. What I am trying to accomplish is to advertise my ASN twice to one of the providers (the cheap one) to cause more inbound bandwidth on the better provider link. The reason why this is such an issue is that both of the providers that I am working with have Level3 for bandwidth and one of them (the one that traffic is not going over) gives me an HSRP handoff for redundancy so I would rather have that provider receiving more data. As well I am contracted for more bandwidth on that link. I can prepend for all the routes that are coming into my box (stored in the routing table) just fine, but I want to modify my outgoing route so it shows my ASN twice on that one link to offload data.
To make it even more simple:
Provider 1 (Best routes, higher bandwidth commitment): Internap, Level3, Time Warner Telecom
Provider 2 (Not always the best routes, lower bandwidth commitment, but receiving far more data due to Level3): Cogent, Level3
And about 90% of traffic hitting my network is coming over Provider 2 because the Level3 connection there just looks that much better I guess. So I want to find the way to modify the routes that I am advertising to show the AS number twice instead of just once to the world.
When I use a prepend on an out-filter, does that modify the BGP announcements to show as a prepend? Prepend works find on an in-filter – I can see my ASN showing up however many times I put in for those routes and it accurately reflects in the bandwidth usage as well.
Well, I figured it out and sure enough changeip was right – but there was a trick. My setup is that I have a single head-end router that runs our BGP out to the Internet and then we have the rest of our network as a static IP from that. I have an out-filter for both of my connections and that filter is set to do an invert-match for the block of IP addresses and then discard. I found that if I create a second filter with the same name as the first out-filter, and in it I tell it to accept, and set BGP prepend to the number (other than 1, in this case I had to use 3 for load balancing) I am now pushing about 40/60, obviously still not 50/50, but much better than the 5/95 that I was seeing before.
how large is your route table on 2.9.43 ? I’m nervious to upgrade because bgp is still flakey with too many routes - would like to hear it’s more stable now.