Faster 'Net growth rate raises fears about routers

Mon Apr 2 12:29:12 UTC 2001

At 20:09 02/04/01 +0800, Adrian Chadd wrote:

>On Mon, Apr 02, 2001, Travis Pugh wrote:
> >
> >
> > Not to oversimplify, but assuming we can continue to separate forwarding
> > from the routing process itself, is this really a situation that calls for
> > a complete redesign of BGP?  If you look at the routing processors on
> > Cisco and Juniper hardware, Cisco's GSR is using a 200Mhz MIPS RISC
> > processor and Juniper is using a 333Mhz Mobile Pentium II.
> >
> > With RISC reaching 1Ghz and Intel pushing 2Ghz, it appears that the actual
> > processors in use by the 2 big vendors are a couple of years behind.  What
> > happens to the boxes ability to process a 500,000 route table if you
> > quadruple it's memory and give it 5 times more processing power?
> >
> > Also, it would likely require a re-write of software, but what's keeping
> > us from using SMP in routers?
>
>Performance of a routing protocol is not a function of just
>the CPU avaliable.
>
>Performance of a routing protocol is a function of the CPU
>avaliable and the network characteristics.
>
>*shakes head* people keep forgetting this. Do you guys also
>think you can solve the internets problems by adding more bandwidth?

I think the current large routers can handle flapping (50,000 routes every 
30 seconds):
http://www.lightreading.com/document.asp?site=testing&doc_id=4009&page_number=12
and they can handle large BGP tables (Cisco: 400K, Juniper: 2.4M):
http://www.lightreading.com/document.asp?site=testing&doc_id=4009&page_number=10

The problem is all the legacy Cisco 7500s in the core that are defaultless 
and currently carry 99,000 routes.  I think Geoff is wrong in his statement 
that the problem is not routing table size, but rather flapping.  To quote 
Geoff: "It's not the size of the table, but the number of updates per 
second that kills a router stone dead."  But the rate of flapping is 
proportional to the size of the routing table, IMO.  If you have 1000 
routes in your table, and on average 5% of the nets will flap every 60 
seconds, that comes to 50.  If you table is 100,000 and the same 5% will 
flap, that comes to 5000 every minute.  Reduce the table size and you 
*will* affect the flapping as well.

-Hank

>Adrian
>
>--
>Adrian Chadd            "The fact you can download a 100 megabyte file
><adrian at creative.net.au>  from half way around the world should be viewed
>                             as an accident and not a right."
>                                         -- Adrian Chadd and Bill Fumerola