Subject: Re: Open Routing Area meeting in Vienna

From: Curtis Villamizar <[email-masked]>
Date: Fri, 01 Aug 2003 14:33:14 -0400

In message <[email-masked]>, Geoff Husto
n writes:
> At 04:40 PM 30/07/2003 -0400, Eric Rosen wrote:
> 
> >Kurt> We all know that BGP doesn't scale
> >
> >Yes,  that  must be  what  prevented the  Internet  from  ever getting  very
> >large. ;-)
> 
> I suspect in this comment that Eric is  skipping across some amazing efforts
> by a small pool of folk to reign in some of the more extreme forms of
> deployed routing abuse (no, I do not count my own small efforts in this pool
> of individuals). Keeping the network vaguely stable at it's current size
> is taking increasingly large amounts of manual effort, and no, this
> cannot scale indefinitely.

Is that an inter-provider coordination problem or a protocol problem?

As I understand it BGP does support aggregation which reigns in the
problem that is putting stress on scaling.  Operators are only able to
provide the simplest single site or single provider aggregation though
the protocol can do better.  A second (possibly greater) problem is
inability to provide assurances of generous address renumbering grace
periods (extending to near infinite if needed) has resulted in far
more provider independent addresses being allocated than the impact of
an infinite renumbering grace period would have ever produced.  Those
are inter-provider operational problems.

As I also recall, there were efforts in the RPS WG to use the routing
registry to coordinate aggregation across providers plus arguments for
generous address renumbering grace periods from a subset of operators
going back as far as 6-8 years ago.

Therefore the BGP protocol scales.  The operators are a bunch of screw
ups, and the protocol can't fix that.  :-)

> There _are_ problems in BGP deployments, and overloading the running
> instance of the protocol to carry more information related to various overlay
> signalling applications does not in itself assist in improving the situation.
> For me its a counter-intuitive action that increases the level of operational
> reliance on a single element of the network. But as Randy and Kurt have
> said this already there's no point in my repeating it.

I wholeheartedly agree.  Regardless of the cause, overloading BGP is
likely to make the situation worse.  That also doesn't have to happen,
but the vendors are screw ups too and are unlikely to get the internal
scheduling coded very well or not break anything making the changes.  :-)

> Geoff

Either way (overloading BGP or a new protocol) is in theory viable,
but people on this list have cited overloading BGP as too great a risk
for a protocol that is critical to operation of the Internet.  The
idea of distributing multicast over BGP died almost a decade ago, yet
VPN use of BGP survived and thrives.  The difference may be that the
2546 use of BGP has been strictly single provider.  Likewise, PW may
prove to be strictly single provider in practice.  IPV6 and telephony
are not.  While IPv6 may be able to start out with isolated islands of
IPv6, it may be less likely that this will work for telephony and
there may also be far more resistance to this.

Curtis

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From: Curtis Villamizar <[email-masked]>
Date: Fri, 01 Aug 2003 14:33:14 -0400

Curtis

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From: Geoff Huston <[email-masked]>
Date: Sat, 02 Aug 2003 06:52:32 +1000

>Is that an inter-provider coordination problem or a protocol problem?

Both - its remarkably easy to do the Wrong Thing on a global scale.
The fact that its too easy is a use issue. The fact that the consequences
are immediately promulgated globally can be interpreted as a protocol
issue. (see the ptomaine work on attempting to limit propagation of
routing  noise).

Geoff

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From: Geoff Huston <[email-masked]>
Date: Sat, 02 Aug 2003 06:52:32 +1000

Geoff