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Re: Level3 Question

  • From: Lincoln Dale
  • Date: Sat Nov 12 01:34:29 2005


i think you misunderstand the h/w / s/w distinction here.

BGP is a 'control-plane'-driven protocol. control-plane = software.

no vendor would have BGP "in hardware" per-se (although its forseeable that they may have 'AS# accounting for netflow' in h/w and that may be limited to addressing 16-bits).

"forwarding a packet" (i.e. data-plane path) is typically in h/w in many {modern,large} routers. even if the routing protocol is based on AS#s, forwarding is typically based on a RIB creating a FIB.
a FIB typically doesn't contain AS# information as there is no need to - you're not 'forwarding' on AS#, you're forwarding on Destination address.

i think the distinction of "old hardware" that the original poster was trying to make was really one of things like RAM and Flash RAM space. if we take "Cisco routers" as an example, it may be that 32-bit AS# support mandates the use of the fictional IOS 12.666S software train which probably won't fit in the 16MB RAM and 16MB FLash on a 15-year-old c2500 series router.


cheers,

lincoln.
NB. obvious 12.666S is fictional. don't try to read anything into that. and if its not obvious, no i'm not officially talking for Cisco.


Wayne E. Bouchard wrote:
Okay, so as people pointed out, I forgot that hardware engineers like
to make assumptions about software for the sake of efficiency in ASICs
and the like. So add a few exponents of pain. Still shouldn't be *all*
that bad I wouldn't think.

On Fri, Nov 11, 2005 at 03:19:45PM -0700, Wayne E. Bouchard wrote:
On Fri, Nov 11, 2005 at 09:41:49PM +0000, Per Gregers Bilse wrote:
On Nov 11,  1:14pm tony.li@tony.li wrote:
The only way to get 32-bit AS number support deployed is to run out of AS numbers in
the 16 bit space.
Exactly.

  - When will the Internet deploy X?

  - Just before it's too late.

How many people on this list remember the transition from BGP3 to
BGP4 and CIDR?  This was, uhh, about 12 years ago.  Before that there
was an EGP to BGP transition, but that was less of an issue.

But history will repeat itself.  Not that I see any great evil in that --
people are always busy, have always been.  It's a case of which priorities
are most pressing, so, indeed, yes, the only way is to run out of the
existing resource.  Likewise for whatever will provide more address space.-)

  -- Per
I think, however, that this will be less dramatic than other
things. This is a "relatively" simple software change. The one thing
it *will* do is make sure that all the old hardware out there that
runs BGP won't work anymore and have to be updated. This is arguably a
good thing. Also remember that this is still some time away. Getting
ever closer, but still a future event.

---
Wayne Bouchard
web@typo.org
Network Dude
http://www.typo.org/~web/
---
Wayne Bouchard
web@typo.org
Network Dude
http://www.typo.org/~web/










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