Aggregation & path information [was: 200K prefixes - Weekly Routing Table Report]
jared at puck.nether.net
Fri Oct 13 19:26:35 UTC 2006
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
> >added the announcement to my aggregation recommendations lightning
> >;-) 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
> 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 Mauch | pgp key available via finger from jared at puck.nether.net
clue++; | http://puck.nether.net/~jared/ My statements are only mine.
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