Hi,
Twitch's network operations department uses BIRD as a centralized looking glass. It's a BGP route reflector that is peered with all our border routers. Staff use the route reflector to inspect how a destination network can be reached from our different points-of-presence. Some peers will advertise the same IP as part of different prefix lengths, likely due to aggregation or filtering. For instance, one provider advertises 117.120.24.0/22 to us, but all others only advertise a /21. Querying SHOW ROUTE on the looking glass shows the /22 on one border router, and hides the /21's. This makes sense as a routing decision from the location of the looking glass, but doesn't give us the global visibility we want. I have a patch which adds an option to SHOW ROUTE to reveal all prefixes, regardless of length / best-match, covering a particular IP. This produces tons of output. I am also working on an option to print the single best prefix for each unique BGP.next_hop / BGP.originator_id. This gives us exactly what we want: the route taken to a particular IP from each border router. Would the community be interested in integrating this feature? If so, I'll start the process here to get a patch released publicly. Thanks Andrew Francis | *Twitch* <http://www.twitch.tv/> | Engineering
