[c-nsp] full routing table

[Łukasz Bromirski]

Alex Howells wrote:
>>> Thanks guys :)  Was just pondering whether a Catalyst 4948 would be good
>>> enough for deployment with two partial feeds, as 76xx series is somewhat
>>> expensive for that particular project!
>>>
>>> Guessing the FIB on it will be the limiting factor.
>> Very very partial feeds.  The 4948 is limited 32,000 routes.  Even the 
>> 4900M is limited to 200,000.
>>
>> http://tinyurl.com/2zd3v4
>>
>> If you want to carry full tables you'd be better off looking at routers 
>> and not switches.  I have 3800s and 2800s with full tables (even had 
>> some 3600s).  If this is a new purchase then I'd recommend a 7200 such 
>> as the 7201.
> 
> Asking purely out of 'curiosity' because a friend who works for an 
> up-and-coming social network aggregator is needing to expand his 
> network, starting to take on their own feeds, etc.
> 
> They've acquired a couple of Catalyst 4948's on the advice from a 
> network engineer that they'll take two full tables.

Alex, You need to be aware of two things: architectures in which
FIB is in the RAM (800/1800/2800/3800/7200), and in the hardware
(TCAMs/etc) - 7600/12000/CRS-1/Cat2/3/4/6k. I assumed You're asking
for software architectures, as usually BGP is implemented on those
boxes, however valid points appeared on this thread as far as
PFC3B/3C and PFC3BXL/CXL is concerned on 7600 platform. For full
BGP table You need XL versions, to be able to fit >249k prefixes for
IPv4.

And unfortunately, all smaller Catalysts that can route and support
BGP (3/4k) can't support such number of routes (usually 10-12 or
20k, with Sup6E for 4500E supporting 256k but that is already
too low for full BGP table, however nobody positions 4500E as
internet-edge router).

-- 
"Don't expect me to cry for all the     |               Łukasz Bromirski
  reasons you had to die" -- Kurt Cobain |    http://lukasz.bromirski.net