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Chapter 36
IP Policy Routing
This chapter covers setting and applying policies used for IP routing.
36.1 IP Policy Routing Overview
Traditionally, routing is based on the destination address only and the IAD takes
the shortest path to forward a packet. IP Routing Policy (IPPR) provides a
mechanism to override the default routing behavior and alter the packet
forwarding based on the policy defined by the network administrator. Policy-
based routing is applied to incoming packets on a per interface basis, prior to the
normal routing.
36.2 Benefits of IP Policy Routing
•
Source-Based Routing – Network administrators can use policy-based routing
to direct traffic from different users through different connections.
•
Quality of Service (QoS) – Organizations can differentiate traffic by setting
the precedence or TOS (Type of Service) values in the IP header at the
periphery of the network to enable the backbone to prioritize traffic.
•
Cost Savings – IPPR allows organizations to distribute interactive traffic on
high-bandwidth, high-cost paths while using low-cost paths for batch traffic.
•
Load Sharing – Network administrators can use IPPR to distribute traffic
among multiple paths.
36.3 Routing Policy
Individual routing policies are used as part of the overall IPPR process. A policy
defines the matching criteria and the action to take when a packet meets the
criteria. The action is taken only when all the criteria are met. The criteria
includes the source address and port, IP protocol (ICMP, UDP, TCP, etc.),
Contivity 251 VPN Switch User's Guide
36-1
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