[c-nsp] Question on 7204vxr modules

[Justin M. Streiner]

On Thu, 10 Jul 2008, Steven Pfister wrote:

> We have a 7204vxr currently in use as our border router. As part of a 
> transition of our upstream bandwidth from an ATM connection to gigabit 
> Ethernet, we need to replace some of the modules.
>
> The router currently has a PA-A6-OC3MM module connecting to our service 
> provider (in the lower right slot). The IO controller has 2 FE/E ports 
> (don't have the part number). We want to replace the IO controller with 
> a c7200-I/O-GE+E and the other module with a PA-GE. Our questions are:
>
> - As a first step, we're going to replace the I/O controller with the 
> new one using a FE GBIC, and put the PA-GE in along with the PA-A6-OC3MM 
> until its time to cut over to gigabit Ethernet. Is there any 
> restrictions  on where we can put the PA-GE during this time? Can it be 
> any slot?
> - Where is the configuration stored? Is it on the flash card? When we 
> put the new IO controller in, can we just move the flash card over?

You don't mention what type of processor engine you're using, so there are 
a number of caveats to consider.

You will not get anywhere close to line-rate out of a PA-GE, regardless of 
what processor you're using.  It's a limitation of the PCI buses on that 
platform.  If you need closer to gig-e line-rate on a VXR, you really want 
to replace the processor blade with an NPE-G1 or NPE-G2, plus those 
processors have compact flash slots for storing images and so forth.

Also note that many processors for the 7200/XVR are at or near the 
end of their life cycle, so getting support may be an issue, should you 
need it.  In fact, everything except the NPE-G1 and G2 are at least 
end-of-sale now - the NPE-400 went end-of-sale earlier this year and most 
of the rest are already end-of-life/support.

The config is stored in NVRAM, which I think is on the NPE, but you still 
need a flash/CF clot available for to hold IOS images, crash dumps, etc.

If you're running an older NPE, like a 225, 300, 400 or NSE-1, I don't 
think those have built-in flash/CF slots, so you'd still need an I/O 
controller for its flash slot.

The VXRs have two PCI busses, one covers slots 0/1/3/5 and the other 
covers slots 2/4/6.  Each bus is limited to 600 'bandwidth points', so any 
configuration of port adapters is valid as long as each bus stays under 
600 points.  That can be tricky.  A PA-GE is 400 points by itself.  That's 
another reason to look at an NPE-G1 or G2.  It has built-in GE ports, so 
they don't touch the PCI busses and are not subject to the bandwidth point 
limitations like the PA slots.

jms