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Re: Aggregation & path information [was: 200K prefixes - Weekly Routing Table Report]
On Fri, Oct 13, 2006 at 03:14:38PM -0400, Patrick W. Gilmore wrote: > > On Oct 13, 2006, at 3:04 PM, Philip Smith wrote: > > >I was kinda hoping that it would hit 200K on Tuesday, then I could > >have > >added the announcement to my aggregation recommendations lightning > >talk! > >;-) Bit sad that a 200K table can be aggregated down to 109k prefixes > >with no loss of path information (in my BGP table view). > > I find this interesting. > > Obviously the table contains kruft. But I know we could not shrink > it to 109K prefixes without losing something from where I sit. Are > you sure there's no additional path info? > > If there were a way to guarantee certain prefixes are completely > superfluous, we could make a hit list of just those providers, then > ridicule or filter or cause them pain in some way to make them stop > causing us pain. I haven't seen that type of report posted publicly, > just "this CIDR can fit in that one" without actual guarantees that > _paths_ are equivalent. (Usually the origin AS is matched as well as > the prefixes, but that's not the same as guaranteeing the path is > equivalent.) > > Of course, this is non-trivial. But then neither is aggregating the > global table. :) how much of this could be mitigated if people properly announced aggregates and used a provider-local no-export to balance their links with them? it does make those policies more complicated than the simple cut+paste examples that they've likely used in the past, but could possibly allow the "traffic-eng" with their upstream without the global pollution. - jared -- Jared Mauch | pgp key available via finger from firstname.lastname@example.org clue++; | http://puck.nether.net/~jared/ My statements are only mine.