Appendix A Caching Solutions and Performance 123
Using a WCCP-enabled router for transparency
A WCCP 2.0-enabled router can send all port 80 (HTTP) traffic to the Intel
NetStructure Cache Appliance, as shown in Figure 4. After the WCCP router
sends port 80 traffic, the ARM readdresses port 80 to the appliance proxy port (by
default, port 8080). Then the appliance processes the request as usual, retrieving
the requested document from the cache if it is a hit and sending the response back
to the client. Along the way, the ARM readdresses the proxy port in the response
header to port 80 (undoing the readdressing it did on the way to the appliance).
The user then sees the response exactly as if it were sent directly from the origin
server. In addition to port 80 (HTTP) traffic, WCCP 2.0 supports more protocols
including NNTP (port 119 traffic).
Figure 4 Using a Cisco IOS router to send port 80 traffic to several Intel NetStructure
Cache Appliances
WCCP provides the following routing benefits:
✔The WCCP-enabled router and the appliance exchange heartbeat messages,
letting each other know they are running. The WCCP router automatically
reroutes port 80 and port 119 traffic if the appliance goes down.
✔If several appliances receive traffic from a WCCP router, WCCP balances the
load among them. The group of appliances is called a WCCP cache farm.
end users
Intel NetStructure Cache Appliance 1, 2, and 3
internet
Cisco IOS router
switch or hub
80
all
all