Hi Amol,
- By enabling WCCP how much increase in CPU utilization % can be expect?
I doubt if we can confirm this. But since the first packet will be software switched then yes there will be a spike in CPU.
- CPU % increase is depend on number of Accesslists?
Yes it will depend.
- Is there any supporting document from Cisco for CPU utilization % with WCCP?
Please find below link for same. I am also putting a SNIP which would be of your interest regarding the query.
Link : http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/116134-config-wccp-6500-00.html
A common question about WCCP on the Catalyst 6500 is, "Why does the CPU utilization increase when I enable WCCP?" When hash-based assignments are in use, the software-based processing of the initial packet in each flow places a burden on the CPU and is most often the cause of increased utilization. With the currently available Policy Feature Card 3 (PFC3) forwarding hardware, if WCCP is configured as an egress feature or if hash-based assignment is in use (ingress or egress), some level of software processing is always required.
The use of the hash-based assignment method impacts these features:
NetFlow table - The number of entries supported by the PFC is limited, and the flow mask changes to interface full-flow for the entire NetFlow table.
CPU utilization - There is an increase in CPU utilization as the first packet in each flow is software switched.
Performance - The rate at which traffic is sent to the CPU for lookup is limited so that the CPU is protected.
NetFlow features - Other features that use NetFlow resources might be impacted if the NetFlow resources are consumed by WCCP.
HTH,
Nikhil
