User Manual

Configuring IP Policies
316 Enterasys X-Pedition User Reference Manual
Setting Load Distribution for Next-Hop Gateways
You can specify up to four next-hop gateways in an ip-policy statement. If you specify more than
one next-hop gateway, you can use the ip-policy set command to control how the load is distributed
among them and to check the availability of the next-hop gateways.
Note: To ensure that a gateway for policy-based routing is available, use the ip-policy set
command and enable the pinger task.
By default, each new flow uses the first available next-hop gateway. You can use the ip-policy set
command to cause flows to use all the next-hop gateways in the ip-policy permit statement
sequentially. For example, the following command picks the next gateway in the list for each new
flow for policy ‘p1’:
The ip-policy set command can also be used to check the availability of next-hop gateways by
periodically querying them with ICMP_ECHO_REQUESTS. Only gateways that respond to these
requests are used for forwarding packets. For example, the following command checks the
availability of next-hop gateways specified in the policy ‘p1’:
Note: Some hosts may have disabled responding to ICMP_ECHO packets. Make sure each next-
hop gateway can respond to ICMP_ECHO packets before using this option.
Applying an IP Policy to an Interface
After you define the IP policy, it must be applied to an inbound IP interface with the ip-policy
apply command. Once the IP policy is applied to the interface, packets start being forwarded
according to the IP policy. (See the Enterasys X-Pedition Command Line Interface Reference
Manual for complete syntax information for the ip-policy apply command.)
For example, the following command applies the IP policy ‘p2’ to the interface ‘int2’:
Applying an IP Policy to Locally Generated Packets
You can apply an IP policy to locally-generated packets (that is, packets generated by the XP). For
example, the following command applies the IP policy ‘p2’ to locally-generated packets:
xp(config)# ip-policy p1 set load-policy round-robin
xp(config)# ip-policy p1 set pinger on
xp(config)# ip-policy p2 apply interface int2
xp(config)# ip-policy p2 apply local