Use the commands in this chapter to configure On-Demand Routing (ODR). For ODR configuration information and examples, refer to the "Configuring On-Demand Routing" chapter of the Network Protocols Configuration Guide, Part 1.
To configure a router to accept On-Demand Routing (ODR) routes from a stub routers, use the router odr global configuration command. To disable ODR, use the no form of this command.router odr process-id
Number of a process that identifies the routes to the other ODR routers.
The router ignores any received ODR information.
This command first appeared in Cisco IOS Release 11.2.
Use this command on hub routers to enable ODR to update the routing table with information learned via ODR stub routers.
The following example sets up the routers in the distribution list to accept ODR routes from the specified access list:
router odr distribute-list 101 in access-list 101 permit ip host 10.0.0.1 126.96.36.199 255.255.255.0 access-list 101 permit ip 188.8.131.52 255.0.0.0 184.108.40.206 255.255.255.0 router ospf 1 redistribute odr subnets
You can use the master indexes or search online to find documentation of related commands.
To adjust ODR network timers, use the timers basic router configuration command. To restore the default timers, use the no form of this command.timers basic update invalid holddown flush [sleeptime]
Rate in seconds at which updates are sent. This is the fundamental timing parameter of the routing protocol.
Interval of time in seconds after which a route is declared invalid; it should be at least three times the value of update. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters holddown. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets.
Interval in seconds during which routing information regarding better paths is suppressed. It should be at least three times the value of update. A route enters into a holddown state when an update packet is received that indicates the route is unreachable. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. When holddown expires, routes advertised by other sources are accepted and the route is no longer inaccessible.
Amount of time in seconds that must pass before the route is removed from the routing table; the interval specified must be at least the sum of invalid and holddown. If it is less than this sum, the proper holddown interval cannot elapse, which results in a new route being accepted before the holddown interval expires.
(Optional) Interval in milliseconds for postponing routing updates in the event of a flash update. The sleeptime value should be less than the update time. If the sleeptime is greater than the update time, routing tables will become unsynchronized.
update is 90 seconds
invalid is 270 seconds
holddown is 280 seconds
flush is 630 seconds
sleeptime is 0 milliseconds
This command first appeared in Cisco IOS Release 10.0.
The basic timing parameters for ODR are adjustable. Since this routing protocol is executing a distributed, asynchronous routing algorithm, it is important that these timers be the same for all routers and access servers in the network.
The following example sets updates to be broadcast every 5 seconds. If a router is not heard from in 15 seconds, the route is declared unusable. Further information is suppressed for an additional 15 seconds. At the end of the suppression period, the route is flushed from the routing table.
router odr 109 timers basic 5 15 15 30
Note that by setting a short update period, you run the risk of congesting slow-speed serial lines; however, this is not a big concern on faster-speed Ethernets and T1-rate serial lines. Also, if you have many routes in your updates, you can cause the routers to spend an excessive amount of time processing updates.