In a WCCP deployment with multiple Edge SWG appliances in a pool, one appliance is selected as the lead appliance or "Designated Cache".
The "Designated Cache" is the appliance responsible for notifying the router or routers how redirected traffic should be distributed between the Edge SWG appliances in the WCCP pool.
To find the "Designated Cache" from the Edge SWG CLI execute the 'show wccp statics' from enable mode and look for the "Designated Cache" line:
ProxySG#show wccp statistics
;WCCP Statistics
;Version 1.3
Current time :Wed, Feb 10 2010 03:16:46 UTC
Last stats reset time:Fri, Feb 05 2010 03:06:34 UTC
<Other WCCP Statistics is removed>
Designated Cache :<IP Address of ProxySG>
<Other WCCP statistics is removed>