On Sat, Sep 22, 2018 at 08:22:52AM +0100, Tom Smyth wrote: > OpenBGPd Feature Request / Question if the Feature Request > is something the community would use ? > > Background, > Ideally we would run full tables so that we have visibility > on reachibility of a prefix via a transit provider, > > Problem: routers that support this functionality Reliably > are quite expensive, (or inexpensive and unreliable) > Workaround: > so many people accept default over BGP from transit and > then peer locally on the exchange > Issue with this is that you lose visibility of wheather > an ip is actually reachable via your transit provider > > > Question: > is it feasible to have a hybrid between a default route > for transit and bgp full views of transit? > Is it feasible to: > a) take two or more full bgp feeds from transit, > b) diff them continuously on a software route server, > c) install a default route to your preferred transit provider > on your lower cost L3 Switches / Routers > d) install differences in prefix reachibilitity to the > appropiate transit provider (which would otherwise not > be reachable via your preferred transit provider) > > > Why am I asking this ? > I want to have the advantages of full views of internet > but I want the simplicity of a single default route + > any exceptions. and use more cost effective hardware > > Im asking this in the context of an ISP which is not > proividing transit to other ISPs > > I ideally would like to run multihop BGP to my transit > providers, > and then use a L3 switch for forwarding in hardware > (something like an arista / Broadcom Trident II ) > which can take up to around 128k routes on its asics > > If it is feasible to do what is involved in adding it > to OpenBGPd and is this something the wider community > would use / enjoy ? > > Your feedback would be really appreciated...
Yes, it is feasible. Spotify is doing something like this. https://blog.ipspace.net/2015/01/sdn-router-spotify-on-software-gone-wild.html In short: analyse where 80% of your traffic goes to (nfsen) and write a filter to only install those prefixes in addition to the default route. A year ago I did this analysis for the network I operate: 80% of our Internet traffic went to 20 ASs and was covered by ~9k prefixes. Cheers, Remi
