Brocade Communications Systems ServerIron ADX 12.4.00 Service Manual download pdf (Page 84)

72 ServerIron ADX Advanced Server Load Balancing Guide

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Content aware cache switching

1. Since the URL ends with "gif", the CSW policy on the ServerIron ADX directs the request to one

of the cache servers in Server Group ID=1.

2. When a server group consists of more than one cache server, the ServerIron ADX uses a

hashing algorithm to select one of the cache servers, and directs the request to the selected

cache server.

3. Since this is the first time the content is requested, the selected cache server does not have

the content stored, so the cache server retrieves it from the Internet.

4. The cache server receives the content, caches it, and sends it to the requesting client.

The next time a client requests the content, the following events take place.

1. Since the URL begins with "gif", the CSW policy directs the request to one of the cache servers

in Server Group ID=1.

2. The ServerIron ADX hashes the URL string, selecting the same server it selected previously.

3. This time the cache server has the content and does not have to go to the Internet to get it; it

sends the cached content to the requesting client.

Setting up content aware cache switching consists of the following steps.

1. Enabling TCS on the ServerIron ADX

2. Setting up CSW policies

3. Configuring the cache servers

4. Assigning the cache servers to a cache group

These tasks are described in the following sections.

Enabling TCS

To enable TCS on all interfaces (globally) of the ServerIron ADX shown in Figure 19, enter the

following command.

ServerIronADX(config)# ip policy 1 cache tcp 80 global

Syntax: ip policy <index> cache | normal | high tcp | udp <tcp/udp-portnum> global | local

Setting up the CSW policies

The CSW policies define selection criteria for URL strings and specify what happens when a URL

string matches the selection criteria. In content aware cache switching, if an HTTP request contains

a URL string that matches a policy’s selection criteria, the HTTP request can be sent to a

load-balanced cache server group or to another policy for additional matching.

NOTE

The CSW policies discussed in this section apply to the example in Figure 19 on page 71.

The following commands define a CSW policy called p1.

ServerIronADX(config)# csw-rule r1 url suffix “gif”

ServerIronADX(config)# csw-policy p1

ServerIronADX(config-csw-p1)# match r1 forward 1

ServerIronADX(config-csw-p1)# default forward 2

ServerIronADX(config-csw-p1)# exit

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Brocade Communications Systems ServerIron ADX 12.4.00 Service Manual Page 84