Route filtering is Internet hygiene
Networks filtering what their neighbours announce is what stops one operator's mistake becoming everybody's outage.
It is unglamorous, largely invisible, and the main reason routing incidents are usually contained. It relies on operators doing something that benefits others more than themselves, which is a fragile basis for infrastructure and has worked well enough so far.
More on Internet routing
- BGP announces reachability, not truthA claim, not a proof
- BGP hijacking can redirect traffic before applications see itThe points move under the train
- Route leaks can be accidental and disruptiveThe whole motorway down a side lane
- RPKI validates route origins, not the whole pathOnly the first pair of hands is signed for
- More specific Internet routes usually winThe narrower claim takes it
- Anycast sends one address to multiple placesOne address, many doorsteps