Yakov Rekhter previously wrote:
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