Appendix A Caching Solutions and Performance 125
Figure 5 illustrates policy-based routing for HTTP objects. This routing scheme
has the following characteristics:
✔All client Internet traffic is sent to a router that feeds the appliance.
✔The router sends port 80 (HTTP) traffic to the appliance and sends the
remaining traffic to the next hop router.
✔The ARM translates intercepted requests into appliance requests so they can
be served.
✔Translated requests are sent to the appliance.
✔Web documents to be served transparently are readdressed by the ARM on
the return path to the client, so that the documents appear to have come
straight from the origin server.
An appliance cluster with virtual IP failover adds reliability; if one node fails,
another node can take up its transparency requests. See Virtual IP failover‚ on
page 146.
Figure 5 Using a router to filter HTTP requests
ARM redirection
The ARM can make two changes to an incoming packet’s address: its destination
IP address and its destination port.
✔Typically, HTTP packet destination IPs and ports are readdressed with the IP
address of the Intel NetStructure Cache Appliance and the appliance’s HTTP
proxy port (usually port 8080).
end users
Intel NetStructure Cache Appliance
world wide web
router
non port:80 traffic
non
80
80
all
port:80 traffic