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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.

By configuring route redundancy, you can use a back-up line to route 
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.

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.

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>