Supervisor 2 Question

lamav · ‎10-17-2007

Sometimes Cisco makes it so difficult to understand their products -- or maybe Im just stupid.

Does the SUP2 PFC2 support routing protocols? Or do you have to add the MSFC2? I think you have to add the MSFC2.

This is what it says on the Cisco website:

Â• PFC and PFC2-Perform hardware-based Layer 2, Layer 3, and Layer 4 packet forwarding as well as packet classification, traffic management, and policy enforcement

Â• MSFC2-Performs Layer 3 control plane functions including address resolution and routing protocols

Is there a difference between "layer 2,3 and 4 p

lamav · ‎10-17-2007

For some reason, my question keeps getting corrupted.

The last sentence was supposed to read

"Is there a difference between what Cisco refers to as L2,3 and 4 packet forwarding" and "routing"? I always thought of L3 forwarding as routing....huh??

Jon Marshall · ‎10-17-2007

Hi Victor

Policy Feature Card is primarily responsible for forwarding the packets. The MSFC is responsible for building the routing table, peering with neigbour routers.

You need an MSFC to route traffic at layer 3.

L3 forwarding is routing. It is often called layer 3 switching on Catalysts which basically means there are dedicated ASIC's(Application Specific Intergrated Chip) for the L3 forwarding as opposed to routers which use software.

Yes i agree, sometimes Cisco can make it quite hard to understand things but the 6500 is a complicated piece of kit :)

Attached is a link to an architecture paper on the 6500 which explains all the functions of the PFC/MSFC cards.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper0900aecd80673385.shtml

HTH

Jon

lamav · ‎10-17-2007

Jon, I have known for 10 years or so that an MSFC is the L3 switching (routing) engine. I must have configured 100 of them. But its the language Cisco used that was confusing me....glad you did that sanity check for me. LOL

Jon Marshall · ‎10-17-2007

:). I know exactly what you mean, happens to me all the time. You think you understand something and then read something else that makes you wonder...