[c-nsp] WCCP performance problem on a 7600

[Charles Glass]

Hi,

I have a problem with performance on a 7600 with WCCP enabled.

WCCP has been configured to use GRE forwarding and HASH assignment.

I understand that GRE forwarding with HASH assignment is not the
preferred configuration for WCCP on a 7600 and that GRE is not
supported in hardware.

Configuring L2 forwarding and HASH assignment yields no performance
improvement from what I have seen.

WCCP is applied inbound on two interfaces of an ES20 line card (with
DFC-3CXL). The inbound traffic rate on each port is approximately
250Mbps at 10k pps.

My understanding from the Cisco documentation (referenced below) is
that forwarding should be assisted by the routing hardware when using
L2 forwarding with HASH assignment.

To make full use of hardware redirection the cache engines would need
to be configured with L2 forwarding and mask assignment.

CPU utilisation on the ES20 linecard and RP of the 7600 using GRE
forwarding and HASH assignment:

#sh platform hardware capacity cpu

CPU Resources

 CPU utilization: Module             5 seconds       1 minute       5 minutes

                  1                  31% / 12%            42%             41%

                  5  RP              83% / 72%            80%             81%

                  5  SP              10% /  0%             6%              6%


By comparison a 7200 NPE-G1 will forward ~300Mbps with WCCP configured
inbound at ~60% CPU (GRE forwarding with HASH assignment)

Has anyone seen simlar performance when using WCCP with GRE forwarding
and HASH assigment?

Has anyone else seen the same performance with L2 forwarding and HASH
assignment as with GRE forwarding and HASH assignment?

Has anyone seen better performance using L2 forwarding with HASH
assignment than what I have described?

Is anyone using L2 forwarding with MASK assignment?

Could anyone relate their experiences using WCCP on the 65k/7600 using
different forwarding and assignment methods?

Ideally I would like to use L2 forwarding with MASK assignment. GRE is
not the preferred configuration.

Below are excerpts from a cisco document:

"Catalyst 6500 series switches and Cisco 7600 series routers provide
WCCP Layer 2 Policy Feature Card (PFC) redirection hardware
acceleration."

"Redirection processing is accelerated in the switching or routing
hardware, which is more efficient than L3 redirection with Generic
Routing Encapsulation (GRE)."

"L2 redirection takes place on the switch or router, and is not
visible to the Multilayer Switch Feature Card (MSFC)."

"In order for the router or switch to make full use of hardware
redirection, the content engine must be configured with L2 redirection
and mask assignment"

http://www.cisco.com/en/US/docs/ios/12_4t/ip_appl/configuration/guide/htwccp.html

WCCP configuration:

ip wccp web-cache redirect-list 199 group-list 100 password 7  ***

!
interface GigabitEthernet1/0/5
 ip wccp web-cache redirect in
 ip address 192.168.0.1 255.255.255.0
 ip ospf authentication-key 7  ***
 mls qos trust dscp

!
interface GigabitEthernet1/0/10
 ip address
192.168.1.1 255.255.255.0
 ip wccp web-cache redirect in
 ip ospf authentication-key 7 ***
 mls qos trust dscp
!

Regards,

Charles