verio arrogance

Fri Jul 19 17:05:02 UTC 2002

At 12:16 -0400 7/19/02, Richard A Steenbergen wrote:
>On Fri, Jul 19, 2002 at 11:00:38AM -0400, Daniel Golding wrote:
>>
>>  I think we are at the point where the vast majority of backbone routers can
>>  handle 200K+ routes, at least in terms of memory. The interesting point we
>>  are getting to, is that the most popular router in the world for multihoming
>>  can't handle the routing table. I'm referring to the Cisco 3640, which has
>>  largely supplanted the venerable 2501 as the low-end multihomer's edge
>>  router of choice.
>>
>>  With a reasonable number of features turned on (i.e. SSH, netflow, CEF), the
>>  3640 can't handle two full views anymore, due to it's limitation of 128MB.
>>  While this may be a good thing for Cisco's sales numbers, in this winter of
>>  financial discontent, I wonder how this is effecting the average customer,
>>  and what is generally being installed to replace the 3640s.
>
>If a 3640 customer can't handle multiple full views, why can't they
>filter some junk /24s themselves? This isn't really a good enough reason
>for backbone providers to do the filtering.

That was my thinking also.  I would imagine a lot of customers what a 
full route view, it's what they are paying for especially if they are 
an ISP or multihomed large customer.  They should have their own 
policies then.
>
>As for the convergence time argument, the limiting factor is CPU time,
>not the number of routes or amount of data exchanged (though obviously
>more routes == more cpu). In the core, is there really that big a
>difference between 93k and 113k? On the borders, how much cpu time is
>saved vs how much cpu time is burned doing the filtering?

I would assume a flapping session with a large backbone would cause 
much higher load time and stress on the router then simply a large 
table.  It's the reason why some backbones have Draconian route 
dampening policies, and rightly so.  I would love to see some 
engineers from vendors weight in on this (did I just say that?). 
Most brag that they can handle large tables without a problem.  A 
good question might be, if a large backbone started flapping 150,000 
routes, what would that do to the peers.    Perhaps a better issue 
much be CPU usage of complex route filters on large tables, as a 
limitation on performance.

>
>Which leaves us with the question of, are there still MSFC1's or other
>devices with 128mb memory limits in these networks which are hurting at
>113k? Is there actually a legitimate technical need to filter off 20k
>routes, or are the people doing it stuck in a mental time warp from the
>days when it was a necessity?
>
>Or, is it really just people trying to do the "correct" thing? If you see
>"almost" no change in connectivity after removing 20k of cruft, and the
>very few people who are broken are the ones who needed attention called
>to their poor route announcing skills anyways, maybe it's a good thing
>for reasons other than router performance?

Interesting thought is, there are probably a great many engineers on 
this list that have /24s at their home, that dont enjoy being 
filtered.  Some of us just get tired of reIPing our servers.

dave

>
>--
>Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
>PGP Key ID: 0x138EA177  (67 29 D7 BC E8 18 3E DA  B2 46 B3 D8 14 36 FE B6)

-- 

David Diaz
dave at smoton.net [Email]
pagedave at smoton.net [Pager]
Smotons (Smart Photons) trump dumb photons