[c-nsp] RSP16 drop-in for RSP4?

[LJ Wobker]

On Wed Sep 20, 2006 at 08:09:42AM -0500, Pete Templin wrote:
>Bill Wichers wrote:
>
>> Just a slightly related question: about how many feeds are you able to
>> squeeze into an RSP4 w/ 256MB? Right now I have 1 full view and a partial
>> (filtered from another of our routers) view on one router and run around
>
>Topology: Two GSR core routers, two GSR upstream edge routers.  Edge 
>routers are route reflector clients of the cores but do not receive 
>upstream external routes (hot exit, and propagate your entire set of 
>routes).  Six 7507s as customer aggregation routers, and are route 
>reflector clients of the cores.  Core routers instructed to not reflect 
>client routes to clients; all clients are in turn fully meshed (i.e. 
>full mesh in the POP; route reflectors tie it all together).
>
>The 7507s receive a full table from each local edge router, and receive 
>twin (most of the time) sets of "best route if the core prefers to go 
>outside the POP" routes from the local cores.  The 7507s are all running 
>12.0(27)S5, and are sitting at 13-22MB of free memory.  Way tighter than 
>I'd like to be, and therefore the reason for asking about RSP16s. 
>Nonetheless, knock on wood, we are not seeing any instabilities with 
>such low amounts of free RAM.

Pete-

Remember that in IOS, memory allocation is a "binary solution set" -- when
the system goes to allocate memory it either works or it doesn't  ;-)  

This is unlike some other systems (speaking generally in operating system
terms) where as you get lower on memory the system degrades.  IOS doesn't
swap to disk, so the system runs at 100% speed as long as there is memory
available.

Ultimately, there's nothing wrong with being "low" on memory except that it
means you're statistically more likely to find yourself "out" -- and "out"
is a very very bad place to be.  You need to keep a healthy buffer of free
memory so that when someone accidentally/maliciously dumps 10 thousand more
routes on you, it doesn't break the box.

If you're looking at 13M free, that's sitting dangerously close to The Bad
Place, I'd strongly recommend that you upgrade.

Hope this helps...

--lj

>
>pt
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Lawrence J. Wobker   "Highly trained network monkey"    lwobker at cisco.com
CCIE #5020         Technical Marketing Engineer, Routing Technology Group
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