www.networkbulls.com
Best Institute for CCNA CCNP CCSP CCIP CCIE Training in India
M-44, Old Dlf, Sector-14 Gurgaon, Haryana, India
Call: +91-9654672192
On-demand routing (ODR) is a mechanism for reducing the overhead with routing. Only Cisco routers can use ODR. With ODR, there is no need to configure dynamic routing protocols or static routes at a hub router. ODR eliminates the need to manage static route configuration at the hub router.
Figure 9-8 shows a hub-and-spoke network where you can configure ODR. The stub router is the spoke router in the hub-and-spoke network. The stub network consists of small LAN segments connected to the stub router and a WAN connection to the hub. Because all outgoing traffic travels via the WAN, no external routing information is necessary.
ODR simplifies the configuration of IP with stub networks in which the hub routers dynamically maintain routes to the stub networks. With ODR, the stub router advertises the IP prefixes of its connected networks to the hub router. It does so without requiring the configuration of an IP routing protocol at the stub routers.
ODR uses Cisco Discovery Protocol (CDP) for communication between hub and stub routers. CDP must be enabled for ODR to work. CDP updates every 60 seconds. Because ODR route prefixes are carried in CDP messages, a change is not reported until the CDP message is sent.
The hub router receives the prefix routes from its stub routers. You can configure the hub router to redistribute these prefixes into a dynamic routing protocol to propagate those routes to the rest of the internetwork. Stub routers are configured with a static default route to the hub router.
- Less routing overhead than dynamic routing protocols
- No configuration or management of static routes on the hub router
- Reduced circuit utilization
No comments:
Post a Comment