Technical data

90 ServerIron ADX Advanced Server Load Balancing Guide
53-1002435-01
Sample configurations
2
Policy-based caching
Policy-based caching enables you to selectively cache some web sites but not others, on specific
cache servers. For example, an ISP can use a ServerIron ADX configured for policy-based caching to
redirect HTTP traffic to a series of web cache servers made by different vendors with different
caching criteria.
In the example shown in Figure 22, there are four cache servers with 2 cache servers in one group
(cache group 1) and 2 cache servers in another group (cache group 2). Policy based caching is
applied for traffic destined to Web Server 1, Web Server 2, and Web Server 3.
Access Control List “101” is tied under Cache Group 1. The filter-acl 101 command diverts traffic to
cache 1 and cache 2 that was originally destined to Web Server 3 (IP address 1.1.1.1).
In the same way, Access List “102” is tied under Cache Group 2. The filter-acl 102 command
diverts all the traffic that was originally destined to Web Server 2 (IP address 1.1.1.2) to cache 3
(ch3) and cache 4 (ch4).
The server cache-bypass 103 command divert all the traffic to Internet Web Server 3 (IP address
1.1.1.3). The fundamental use of the server cache-bypass command is to skip the caching
mechanism and send web queries directly to the Internet.
FIGURE 22 Policy based caching topology
Internet
e3
Cache Group 1
Border Access
Router
e4
e7
e6
e5
e1
Organization Domain LAN
Remote Access
Router
10.10.0.0/16
Client Web Queries
40.40.40.100
40.40.40.101
40.40.40.102
40.40.40.103
Web Server 3
1.1.1.1
Web Server 2
1.1.1.2
Web Server 1
1.1.1.3
15.15.0.0/16
80.80.0.0/16
ch1
ch2
ch3
ch4