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Re: Aggregation & path information [was: 200K prefixes - Weekly Routing Table Report]
On Oct 13, 2006, at 3:26 PM, Jared Mauch wrote:
On Fri, Oct 13, 2006 at 03:14:38PM -0400, Patrick W. Gilmore wrote:
Sorry if I wasn't clear before, but I consider path info _just for your first hop upstream_ superfluous for the rest of the Internet. Does anyone think this is an unreasonable restriction?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.
More important question: How many people are doing TE or something and not applying no-export when they could? If you need help fixing that, or even figuring out if you need to fix it, I guarantee you several people on this list would help you, many for free.
This is one of the reasons things become "non-trivial". How do you prove that a disgregate prefix is useless to anyone except that one network?
I do not think it is impossible. But it certain ain't easy.