Re: [RRG] map change due to a path failure?

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

On 2008-03-26 14:12, William Herrin wrote:
> On Tue, Mar 25, 2008 at 8:31 PM, Brian E Carpenter
> <brian.e.carpenter@gmail.com> wrote:
>>  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.
> 
> Hi Brian,
> 
> Well, yes. Isn't that the whole idea?

Yes, but *without* several orders of magnitude more update
traffic. See Scott Brim's message re reachability bits.

    Brian

> 
> 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?
> 
> Regards,
> Bill Herrin
> 

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