[nsp] Hardware WCCP on 6500

[Lincoln Dale]

Hi,

its been a while since i was involved with WCCP but here are the answers 
you're after.

WCCP will be the same regardless of whether the switch is running Native or 
Hybrid.
it will also be the same for Sup2 & Sup720.
for simplicity in the reply, i won't go into the permutations of Sup1.

it "depends" on the mode of WCCP.  for WCCPv2:

if its XOR-based hashing and GRE-based tunnelling to the cache, then WCCP 
will be performed entirely in software on the MSFC and performance will be 
limited to what the MSFC is capable of.
note that non-intercepted traffic will remain in CEF in hardware as there 
will be entries programmed into the TCAMs to punt traffic elegible for 
interception to the MSFC using a layer-4 match.

if its XOR-based hashing and Layer-2-rewrite to the cache, then WCCP will 
be performed entirely in software on the MSFC and performance will be 
limited to what the MSFC is capable of.
note that non-intercepted traffic will remain in CEF in hardware as there 
will be entries programmed into the TCAMs to punt traffic elegible for 
interception to the MSFC using a layer-4 match.

if its HashMask-based hashing and GRE-based tunnelling to the cache, then 
WCCP will be performed entirely in software on the MSFC and performance 
will be limited to what the MSFC is capable of.
note that non-intercepted traffic will remain in CEF in hardware as there 
will be entries programmed into the TCAMs to punt traffic elegible for 
interception to the MSFC using a layer-4 match.

if its HashMask-based hashing and Layer-2-rewrite to the cache, then WCCP 
will be performed entirely in hardware on the PFC with no impact on 
performance.


thus, in summary: if your cache can do "Hash Mask" + "L2 Rewrite" then it 
can scale as high as you wish.
if your caching vendor doesn't support this, ask them why they have an 
incomplete implementation of WCCP.
the specification is open, so there is no reason why they cannot support 
that mode.

note also that 12.1(8b)E14 is relatively old; its been quite a while since 
i was involved with WCCP but there were some critical bugs that got fixed 
around that time.  a later 12.1E would be recommended.


hope this helps.


cheers,

lincoln.

At 04:01 AM 18/09/2003, Antoine Versini wrote:
>Hi.
>
>Could someone tell me if 6500s with SUP2, PFC2 and MSFC2 running CatOS on
>the Supervisor and IOS on the MSFC2 (hybrid mode) do perform the WCCP v2
>redirection in hardware ? The gears run CatOS 7.1(1) and IOS 12.1(8b)E14.
>
>Same question for the gears powered by SUP720, PFC3 and MSFC3 running
>CatOS 8.1(1) on the Supervisor and IOS 12.2(14)SX2 on the MSFC3.
>
>I've browsed through the CCO, but I found different documents
>contradictoring each other. It seems to me that hardware WCCP redirection
>can only be done in native mode and WCCP is software performed on the
>MSFC in hybrid mode...
>
>Thanks,
>vox
>
>--
>Antoine Versini     «Tu vois, ça ne coûte pas plus cher de bien manger.»
>IP Networks Project Manager / T-Online France - Club-Internet
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