Cisco Systems 78-11741-02 manual Configuring On-Demand Routing, IPC-195

Configuring On-Demand Routing

This chapter describes how to configure On-Demand Routing (ODR). For a complete description of the ODR commands in this chapter, refer to the “On-Demand Routing Commands” chapter of the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols publication. To locate documentation of other commands in this chapter, use the command reference master index or search online.

ODR is a feature that provides IP routing for stub sites, with minimum overhead. The overhead of a general, dynamic routing protocol is avoided without incurring the configuration and management overhead of static routing.

A stub router can be thought of as a spoke router in a hub-and-spoke network topology—as shown in Figure 34—where the only router to which the spoke is adjacent is the hub router. In such a network topology, the IP routing information required to represent this topology is fairly simple. These stub routers commonly have a WAN connection to the hub router, and a small number of LAN network segments (stub networks) are directly connected to the stub router.

Figure 34 Hub-And-Spoke Network Topology Example

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These stub networks might consist only of end systems and the stub router, and thus do not require the stub router to learn any dynamic IP routing information.

Cisco IOS IP Configuration Guide

IPC-195