We are doing just this with a couple of 2851's - MPLS/BGP/OSPF/IPv6/NAT for a
small POP. The one 2851 I have in mind is maxed out with 1G third party
approved DRAM and also runs a full BGP table. Initially after boot it takes a
little while to munge the full BGP feed (3 or 4 mins from memory) but after that
it sits at a few percent CPU idle and happily does whatever else I need. Max it
gets up to is about 15% CPU during the day.
The GigE ports support >1500 MTU and MPLS works as expected. I have about 15
DSL services coming in over L2TP to it at the moment, I'd be happy to go to
perhaps 50 or so PPP sessions but after the POP grows past that size I figure we
can financially justify a much bigger device anyway.
Given the 2900 ISRs are now out I wouldn't bother putting in any more 2851s for
this purpose - just go the newer 2900 ISRs and be done with it. For much the
same $$ you get way way more throughput. I would be surprised if a 2951 ISR
won't be sufficient for your needs assuming feature parity with the 2851.
The only point of pain I have with this platform is the per-user QoS via RADIUS,
which is still broken in 12.4T, 15.0M and 15.1(2)T, but supposedly fixed soon
(CSCti80776). It has also been broken on the 7200 platform in 15.0M and later
12.4T, so if that feature is super critical then you may want to choose
something which can run old code that is not affected by the bug.
These routers were not designed as an aggregation routers obviously and they
won't scale to anywhere near a 7200 or ASR, but IOS is IOS and everything we
need on the platform for this environment just pretty much works.
Reuben
On 15/10/2010 3:19 PM, John Elliot wrote:
Hi,
We have a bunch of 7200's currently terminating dsl tails(Also doing
mpls/vrf's etc) - We are rolling out a new site, and have an initial
requirement(6-12months) to only support ~50 DSL tails, and also have a
limited budget - Are there any alternatives to the 7200's that we can use for
the above tasks? (Maybe a 2800 or 2900?)
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