Cisco Cisco Web Security Appliance S670 User Guide
R O U T I N G T R A F F I C T O U P S T R E A M P R O X I E S
C H A P T E R 9 : W O R K I N G W I T H E X T E R N A L P R O X I E S
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R O U T I N G TR A F F I C T O U P S T R E A M P R O X I E S
When the Web Proxy does not deliver a response from the cache, it can direct client requests
directly to the destination server or to an external proxy on the network. You use Routing
Policies to create rules that indicate when and to where to direct transactions. A Routing
Policy determines to where to pass the client request, either to another proxy (as defined by
the proxy group) or to the destination server. It addresses the question, “from where to fetch
content?” You might want to create Routing Policies if you have a highly distributed network.
directly to the destination server or to an external proxy on the network. You use Routing
Policies to create rules that indicate when and to where to direct transactions. A Routing
Policy determines to where to pass the client request, either to another proxy (as defined by
the proxy group) or to the destination server. It addresses the question, “from where to fetch
content?” You might want to create Routing Policies if you have a highly distributed network.
Figure 9-1 shows Routing Policies on the Web Security Manager > Routing Policies page.
Figure 9-1 Routing Policies
When you define multiple external proxies in a proxy group, the Web Proxy can use load
balancing techniques to distribute requests to different proxies defined in the group. You can
choose the following load balancing techniques:
balancing techniques to distribute requests to different proxies defined in the group. You can
choose the following load balancing techniques:
• None (failover). The Web Proxy directs transactions to one external proxy in the group. It
tries to connect to the proxies in the order they are listed. If one proxy cannot be reached,
the Web Proxy attempts to connect to the next one in the list.
the Web Proxy attempts to connect to the next one in the list.
• Fewest connections. The Web Proxy keeps track of how many active requests are with the
different proxies in the group and it directs a transaction to the proxy currently servicing
the fewest number of connections.
the fewest number of connections.
• Hash based. The Web Proxy uses a hash function to distribute requests to the proxies in
the group. The hash function uses the proxy ID and URL as inputs so that requests for the
same URL are always directed to the same external proxy.
same URL are always directed to the same external proxy.
• Least recently used. The Web Proxy directs a transaction to the proxy that least recently
received a transaction if all proxies are currently active. This setting is similar to round
robin except the Web Proxy also takes into account transactions a proxy has received by
being a member in a different proxy group. That is, if a proxy is listed in multiple proxy
groups, the “least recently used” option is less likely to overburden that proxy.
robin except the Web Proxy also takes into account transactions a proxy has received by
being a member in a different proxy group. That is, if a proxy is listed in multiple proxy
groups, the “least recently used” option is less likely to overburden that proxy.
• Round robin. The Web Proxy cycles transactions equally among all proxies in the group
in the listed order.
For information about creating Routing Policies, see “Creating Routing Policies” on page 175.