3Com NETBuilder SI manual Ospf over Dial-On-Demand Dial-Up Lines, Using a Static Route, Using Ospf

Configuring IP Routing 107

OSPF over Dial-On-Demand Dial-Up Lines

If you are going to be running OSPF over dial-on-demand dial-up lines, and you do not want the line to come up just for an OSPF packet, configure a demand interface circuit using:

SETDefault !<port> -OSPF DemandInterface = Enable

With this setting, the router negotiates with the neighbor at the other end of the point-to-point link. If the neighbor agrees that the point-to-point link is a demand circuit, the router suppresses sending OSPF hello packets, which allows the data link connection to be closed when not carrying application traffic. The line will still be brought up every 30 minutes to resynchronize routing table information. For the demand circuit to be cost-effective, make sure that it is isolated from as many topology changes as possible because topology changes bring up the interface.

Configuring Route By configuring route redundancy, you can use a back-up line to route Redundancy traffic if your primary line fails. To configure a back-up line for route

redundancy, configure the line according to Chapter 7 and use either a static route or OSPF. To use other dynamic routing protocols, see Using Enterprise OS Software.

Using a Static Route

If you use a static route on the back-up line, but use a dynamic routing protocol like OSPF on the primary line, use the Override option as described in “Override Option” on page 106.

If you are using static routes for both lines, set the metric for the back-up line to a higher number using the syntax in “Configuring Static Routes” on page 109.

Using OSPF

Make sure the metric of the back-up line is higher than the primary line using:

SHow [!<port> !*] -OSPF Cost

If the cost for the back-up line is lower than the primary line, set the cost manually to a higher number using:

SETDefault !<port> -OSPF Cost = <1-65535>