[c-nsp] Migrating Cat3550 to Supervisor II on 6506

[Pete Templin]

Peter Hicks wrote:

> I'm trying to put a proposal together for replacing the 3550s with
> Supervisor II blades, as the 6500s have Sup1A's and run CatOS 5.5(2).  Some
> questions:
> 
>   1. In business terms, how can I justify putting the routing functionailty
>      directly inside the core switches rather than on 3550s?  From a
>      technical angle, "It's a lot better" would be enough :-)

Currently, your routing functionality is directly limited to the 
bandwidth on the trunks between switches, and performance is also 
limited by the queueing on the 6500 egress port, 3500 ingress scheduling 
to be routed, and 3500 egress port.

>   2. I'm looking at a WS-X6K-S2-MSFC2 (Sup2, 2GE + MSFC2/PFC2), but I'm a
>      bit confused at to the difference between an MSFC and PFC.  Do I need
>      both?  Or just an MSFC?

The native Sup2 can only switch packets at L2.  With PFC and appropriate 
switching modules (most of them; we just learned the hard way that the 
6248s don't) onboard, you can read the packet's L3 QOS information and 
make intelligent queueing decisions while switching.  The MSFC2 is the 
actual router brains.  It actually builds a CEF table for the linecards, 
so the interface ASICs can route themselves.  Incredible performance.

>   3. Will I be able to run IOS natively on the 6506s after upgrading the
>      supervisor?  One of the juniors in our team is learning IOS and finding
>      CatOS a struggle (as we don't make many changes to the 6500s), and I'd
>      like to have IOS everywhere if possible.  Are there any caveats to
>      running IOS on the 6506s?

You can run IOS natively iff you have MSFC (of any version that will run 
on your Sup) onboard.  The conversion is a challenge; I'm still fighting 
with my lab box (after several weeks, I cannot get it to self-boot into 
IOS; my only option is to leave the config registers at 0x0 and hold its 
hand), but it presents a clean, consistent interface that "the troops" 
are used to.

I happen to like certain features in the CatOS config, but do want to 
migrate to IOS as hardware permits.  The Cisco Press Field Manual for 
Catalyst Switches is a great reference for CatOS.

Side note: AFAIK, Sup1A can have the MSFC(1) or the MSFC2 on board.  The 
MSFC is flow-based and memory-limited, so it's not suitable for most 
service provider applications.  Sup2 can have the MSFC2, which is CEF 
based and can hold 512MB.

pt