It should be your problem. You simply loss the part of connectivity... The real world is more complex than you drawn below. There is many reasons causing people to announce class-B networks with the short prefixes. On Thu, 2 Dec 1999, Randy Bush wrote:
Date: Thu, 02 Dec 1999 13:00:17 -0800 From: Randy Bush <rbush@bainbridge.verio.net> To: doug@safeport.com Cc: nanog@merit.edu Subject: Re: Verio Decides what parts of the internet to drop
Apparently for their convenience Verio has decided what parts of the Internet I can get to.
verio does not accept from peers announcements of prefixes in classic b space longer than the allocations of the regional registries.
we believe our customers and the internet as a whole will be less inconvenienced by our not listening to sub-allocation prefixes than to have major portions of the network down as has happened in the past. some here may remember the 129/8 disaster which took significant portions of the net down for up to two days.
the routing databases are not great, and many routers can not handle ACLs big enough to allow a large to irr filter large peers. and some large peers do not register routes.
so we and others filter at allocation boundaries and have for a long time. we assure you we do not do it without serious consideration or to torture nanog readers.
With no notification.
verio's policy has been constant and public.
randy
Aleksei Roudnev, (+1 415) 585-3489 /San Francisco CA/