Technical data

ServerIron ADX Advanced Server Load Balancing Guide 39

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Configuring transparent cache switching

Assigning web cache servers to cache groups

TCS requires all cache servers to belong to a cache group. To assign cache servers to a different

cache group, use the server cache-group <number> command.

The ServerIron ADX uses one of two methods to distribute requests among the servers in a cache

group: a hashing algorithm based on source and destination IP addresses or the least-connection

method.

• The hashing algorithm is the default method for the HTTP and SSL protocols.

• The least-connection method is the default method for all other protocols.

The method can be changed from the default setting for all protocols. Refer to “Increasing the TCS

hash bucket count” on page 54.

In addition, cache groups provide automatic recovery from a failed or otherwise out-of-service web

cache server. If a web cache server failure occurs, ServerIron ADX detects the failure and directs

subsequent requests to the next available cache server or forwards the request directly to the WAN

link. For more information see, “csw-policy <policy-name>” on page 73 and “Redirecting client

requests to an available cache server” on page 57.

To assign Cache Server 1 and Cache Server 2 to the same cache group (as in Figure 9 on page 30),

create the server group and assign the servers to the group, as shown in the following.

For IPv4

ServerIronADX(config)# server cache-group 1

ServerIronADX(config-tc-1)# cache-name server1

ServerIronADX(config-tc-1)# cache-name server2

For IPv6

ServerIronADX(config)# server cache-group 2 ipv6

ServerIronADX(config-tc-2)# cache-name server3

ServerIronADX(config-tc-2)# cache-name server4

Syntax: server cache-group <number> [ ipv6 ]

The <number> variable specifies an integer that identifies cache group you are creating. Up to 14

server cache groups can be assigned to a ServerIron ADX.

The ipv6 parameter specifies that the cache group being created is for IPv6 servers.

NOTE

If IPv6 TCS is enabled, please enable the optimized mode for IPv6 (using the ipv6 optimized-mode

enable command), save the configuration (using the write memory command), and reload the

ServerIron ADX.

NOTE

You can gain additional reliability by using redundant ServerIron ADXs, thus eliminating any single

point of failure in the network path to the web cache server group.

NOTE

While TCS can be configured to support IPv4 and IPv6 cache servers separately or concurrently,

NOTE

Define Pv4 cache servers and IPv6 cache servers in separate cache groups.