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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: routing meltdown
Yakov Rekhter previously wrote: >Nick, >> Of course, but the server condenses all of the paths it learns at the XP >> to just one path per prefix learned at the XP, thus significantly >> reducing the load on the router: now the router has several times fewer >> paths to choose from and store in memory. >The amount of saving depends entirely on the average number of paths per >destination at the XP. Perhaps some empirical data in this area would help >to quantify the possible gain. I don't have this data right now, but no matter: I'm not proposing this just because I think it might help routers cope, I'm proposing it because because I _know_ it would limit the paths an XP router hears at the XP to the number of prefixes at the XP. There are close to 30,000 routes in the Internet right now, which means that an XP router will only hear close to 30,000 paths at that XP; it may hear more from other places, internal as well as external but this routing info and calculation load could also be offloaded to a PC-based route server. CIDR is already slowing route table growth enough to keep 1x full routing manageable for a long time to come. BTW, 2x Internet routing BGP4 info fits in 4-6MB on a Cisco today, meaning that an AS that is multi-homed and hears full Internet routes at each border will only have to carry in its routers as many paths as N times the number of Internet routes at most; an AS connected to all NAPs would have no problem running 32MB routers today and for some time into the future (64MB routers are available from Cisco, which had predicted a route explosion and could well, and should well have had less memory capacity limited routers out a while ago). I don't believe there is any impending routing meltdown. If collocating per-AS route servers at the NAPs helps our routers significantly, then we're doing our job well and we can all sleep at night. But if it's not enough, then I doubt any of the other proposals (centralized per-XP route servers, forced proxy route aggregation), with the exception of moving to IPv6, could help either. Anyone who thinks that unilateral proxy aggregation would help at all is probably wrong; anyone who thinks proxy aggregation by committee can be pulled off has not been paying enough attention to the politics of the Internet. Additionally, unilateral proxy aggregation is a very dangerous and heavy handed approach that could bring quite a few lawsuits as well as government regulation into the game. Or are the proponents of forced proxy aggregation counting on their team of lawyers to scare smaller fry away and settle with the mid-size carriers? >Yakov. > Nick
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