Technical data

ServerIron ADX Advanced Server Load Balancing Guide 99
53-1002435-03
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