[c-nsp] 10G for 6506-E with Sup32-8Gb or replace with 4900M

[Holemans Wim]

We have 3 campus with on each campus a 6506-E/Sup720-10G as 'master router' and a 6506/E-Sup32-8gbit as backup router, in a HSRP config. In each router we also have GBIC boards to connect the different buildings. These Sup32 routers also act as  L2 concentrator for part of each campus.

Now we are thinking about connecting both routers to each other on each campus with a 10G connection. As the Sup32 don't have a 10G yet, we have multiple options to do so.
We can add a 10G board to the chassis, replace the supervisor with a Sup720 or replace the whole router with a 4900M.
If I take a look at listprices, I get 28000$ for Sup720, 20000$ for 6704 (but these are Xenpacks), 37500$ for 6708 and 22000$ for 4900M (base + 10/100/1000 card, dual power).
We have  65XX as routers because we had FWSM boards in them  but these are not used anymore.
Based on the price, it seems we best opt to replace the 6506-E/Sup32 with the 4900M option (there is also a difference in maintenance cost). With Twingig convertors this offers us  a good combination of 10G and 1G SFP ports. For 7500$ we can add a second 8 port X2 board that gives us extra 10G/SFP-ports if needed.

Has anyone had bad/good experience with using a 4900M as router, given the following environment :

-          Router acts as backup router, so in 99.xxx% of the time it only has to forward L2 traffic

-          Only static routes, no active routing protocol.

-          40 vlans, 40 SVI's with ACLs on it

-          No IPv6 for the moment, but according to the specs, the 4900M should handle IPv6 in hardware just fine.

-          No Qos yet, but we are planning to implement that in 2011


I know we lose the netflow capability if the primary router fails, but we can live with that.

All comments are welcome.

Wim Holemans
Network Services
University of Antwerp
Belgium