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Question on about Policy Based Routing (PBR) on MSFC

snakayama
Level 3
Level 3

Hi everyone,

I have a question about Policy Based Routing (PBR) on MSFC.

Does MSFC1 process Policy Based Routing in software or in hardware ?

What about MSFC3 ?

The background of this question is as follows.

Our customer facing CPU utilization issue on MSFC1. The peak CPU utilization on the MSFC1 become about 30%. Hardware component of that Catalyst 6506 is as follows,

Catalyst 6506

SUP1A : CatOS 5.5(3)

MSFC1 : IOS 12.1(2)E

PFC1

The MSFC1 is configured with

8 VLAN interfaces

20 static routes (dynamic routing is not operating)

1 named ACL with 16 entries

2 numbered ACL with 50 entries each

I think above configuration does not effect CPU utilization so much. So I am doubting that PBR raises CPU utilization.

The following PBR configured on the MSFC1.

----------

route-map PBR permit 0

match ip address 111

set ip default next-hop xxx.xxx.xxx.xxx

route-map PBR permit 1

match ip address 222

set ip default next-hop yyy.yyy.yyy.yyy

----------

Now customer is thinking of upgrading the Cat6506 to Cat6504-E.

Hardware component of new Catalyst 6504-E is as follows.

Catalyst 6504-E

SUP720-3B : Cat IOS 12.2(17d)SXB11a

MSFC3

PFC3

And customer similarly uses same PBR configuration also on new Cat6504/MSFC3.

I understand I should test on both MSFC1 and MSFC3 to compare CPU utilization, however unfortunately I can not prepare those system now. So I posted it becasue I would like to know any information.

Would you please let me know MSFC1 process Policy Based Routing in software or in hardware ?, and what about MSFC3 ?

Your information would be appreciated.

Best regards,

6 Replies 6

Jon Marshall
Hall of Fame
Hall of Fame

Hi

I can answer at least part of your questionas i have just had to look this up myself.

PBR is supported in hardware on a 6500 by the Policy Feature Card and Distributed Forwarding Card. Certainly with a PFC3 PBR is supported in hardware with the following caveats (from Cisco doc)

=============================================

Policy-based routing (PBR) for route-map sequences that use the match ip address, set ip next-hop, and ip default next-hop PBR keywords.

=============================================

This is link to full doc for more details

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a00801609f4.html#wp1029188

AFAIK a PFC card will also support PBR in hardware with the same caveats but i could be wrong as i could find no definitive answer on the Cisco site.

Hope this has at least partially answered your question

Jon

Yes, I agree with Jon,

your focus shall be the PFC, and not MSFC. The Policy Feature Card (PFC) and any Distributed Feature Cards (DFCs) provide hardware support for policy-based routing (PBR) for route-map sequences that use the match ip address, set ip next-hop, and ip default next-hop PBR keywords.

Check the release notes about specific behavior of PBR (for example: on 12.2 SX PBR traffic through switching module ports where PBR is configured is routed in software if the switching module resets -> CSCee92191)

For more informations:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a0080160a07.html#wp1027016

Another good advice is 'enable CEF' to improuve the PBR performances:

'ip cef'

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a008075fae6.html

Let me know

HTH

Andrea

Hi,

I actually agree with both Jon and Andrea, but i just have one concern, AFAIK CEF is supported in HW starting from MSFC2 and not MSFC1.

HTH,

Mohammed Mahmoud.

Hi Jon, Andrea and Mohammed,

Thank you very much for your reply.

I understand I should focus on PFC not MSFC. According to the following URL,

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a00800c9470.shtml#wp43942

----------

Policy-Based Routing TCAM and Adjacency Utilization

In Supervisor 2 with PFC2 and Supervisor 720 with PFC3, policy-based routing (PBR) is fully supported in hardware using a combination of the security and feature ACL TCAM and the hardware adjacency table.

----------

PBR is fully supported in hardware in Supervisor 2 with PFC2 and Supervisor 720 with PFC3. So in my case that using PFC1, I think PBR might not be fully supported in hardware.

Best regards,

Correct, Shinichi,

I agree with Mohammed, you need at least a Sup2 MSFC2 PFC2.

HTH

Andrea

Hi Andrea,

Thank you very much for your reply.

I understand it and I plan to test whether PBR effect cpu utilization on SUP720-3B/PFC3/MSFC3.

Best regards,

Shinichi

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