It was a nice feature. In fact, it was one of the senior certified ironport engineer taught me this.
Now, I can only edit the configuration xml file directly. (am I missing something). Nothing in the manuals or the knowledgebase seems to talk about this.
<ip_groups>
<ip_group>
<ip_group_name>outbound</ip_group_name>
<interface_name>InternalNet1</interface_name>
<interface_name>InternalNet2</interface_name>
<interface_name>InternalNet3</interface_name>
<interface_name>InternalNet4</interface_name>
</ip_group>
</ip_groups>
How do i use them? In a filterconfig,
roundrobin_outbound: if true {
alt-src-host ("outbound");
}
force_outbound_src: if (remote-ip == "XXX.YYY.") OR (remote-ip == "YYY.ZZZ") {
alt-src-host ("InternalNet4");
}