Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-acceptown-community-01.txt
Brian Dickson <briand@ca.afilias.info> Wed, 30 April 2008 23:19 UTC
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Date: Wed, 30 Apr 2008 19:20:33 -0400
From: Brian Dickson <briand@ca.afilias.info>
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To: "John G. Scudder" <jgs@bgp.nu>
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Cc: idr idr <idr@ietf.org>, Danny McPherson <danny@tcb.net>
Subject: Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-acceptown-community-01.txt
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John G. Scudder wrote: > On Apr 30, 2008, at 6:39 PM, Danny McPherson wrote: > >> Traffic wasn't the issue. It's more CPU, memory, etc.. Just >> because it's available doesn't mean it's free. >> > > Regarding memory, it needn't be consumed for a this-is-my-own-route > path. (It may be, but this is an implementation decision.) > > You need to be careful about steady-state memory usage vs high-water-mark memory usage. Processing updates chews memory *prior* to installation of entries in various RIBs/FIBs, and unless you have an excess of CPU power (and can handle line-rate packets in the slow path), it isn't possible to feasibly pre-filter without degrading performance. And not pre-filtering means memory gets hit on the transient prior to discarding this-is-my-own-route. > Regarding CPU, remember that you want to optimize the bottleneck, > nothing else matters really. In most cases, the RR is the control > plane bottleneck. Loading it up more to protect the CPUs of non- > bottleneck devices seems like an odd design decision. > > The red flag has gone up. Using the term "*the* bottleneck" means you don't understand the nature of complex systems. Yes, there will *always* be a bottleneck. However, solving for one bottleneck will *always* move the bottleneck to some other place. It may be acceptable for a stable state with several equally-pernicious bottlenecks affecting the system, or to move the bottleneck to a portion of the solution space that scales best (e.g. one that scales as O(n log n) vs one that scales as O(n^2). The two other points I'd like to make, are, that: (1) saying "in most cases" is the same as saying "it's not always the case". Solving for one case without considering other cases is very short-sighted and can cause unforseen consequences. It is much better to *consider* those cases, explicitly, and discuss whether and to what degree they would get affected; and (2) keep in mind - an RR is *strictly* control plane. It is possible for it to reside on a device that also does data plane stuff. However, if RR performance is a huge deal, throwing *computer* hardware at it, rather than *router* hardware at it, is an entirely feasible solution - with likely higher (by orders of magnitude) ceiling on performance that can be bought, and likely at much lower price point than equivalent router vendor RR solutions. RR can achieve equivalent topological solutions (and thus avoid topological variance versus router-based RR's) by sitting as a one-armed device hanging off a core router. There is something to very much consider, however: RR's are fundamentally required to achieve suitable scaling on big non-VPN networks. Please keep those networks in mind when messing about with core BGP protocols. (Never mind that I'm working on something to *really* mess with those same core BGP protocols... but with good reason. :-) ) Brian Dickson _______________________________________________ Idr mailing list Idr@ietf.org https://www.ietf.org/mailman/listinfo/idr
- [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acceptow… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Ilya Varlashkin
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Ilya Varlashkin
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Enke Chen
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Enke Chen
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Enke Chen
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… Robert Raszuk
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Danny McPherson
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… Danny McPherson
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… John G. Scudder
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… Brian Dickson
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… Robert Raszuk
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… UTTARO, JAMES, ATTLABS
- Re: [Idr] Fwd:I-D ACTION:draft-pmohapat-idr-accep… Danny McPherson
- [Idr] Route reflectors [was: Re: Fwd:I-D ACTION:d… John G. Scudder
- Re: [Idr] Route reflectors [was: Re: Fwd:I-D ACTI… Brian Dickson
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… Ilya Varlashkin
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… UTTARO, JAMES, ATTLABS
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… Danny McPherson
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… Jim Guichard (jguichar)
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… Ilya Varlashkin
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jim Guichard (jguichar)
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… UTTARO, JAMES, ATTLABS
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… John G. Scudder
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… Jeffrey Haas
- Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acce… David Ward
- Re: [Idr] Fwd: I-DACTION:draft-pmohapat-idr-accep… Pradosh Mohapatra (pmohapat)
- [Idr] draft-pmohapat-softwire-lb-00.txt Pradosh Mohapatra (pmohapat)