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Re: [RRG] map change due to a path failure?
On Tue, Mar 25, 2008 at 8:31 PM, Brian E Carpenter
> But if we fix that by having the ETR send a map update (actually
> a map withdrawal) and we need that to propagate in less than the
> TCP timeout, haven't we just turned the mapping system into
> a dynamic routing protocol? However, it has to handle
> several orders of magnitude more entries than BGP.
Well, yes. Isn't that the whole idea?
We have this large and growing FIB and it's hideously expensive any
time we have to implement it on traffic flows which are larger than
what a generic x86 can handle. So we move the bulk of that "routing"
out to ITRs at the edge where the traffic flows are small and the only
thing we keep in the high-rate FIBs is the knowledge necessary to get
from the ITRs to the ETRs.
I mean, we get one, possibly two orders of magnitude on the RIB just
by moving it to multicore servers with lots of ram, devices in the $8k
range. RIB growth may be superlinear but it's slower than Moore's Law.
The bottleneck is the FIB, specifically on devices with a
larger-than-COTS traffic flow. Right?
William D. Herrin ................ email@example.com firstname.lastname@example.org
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