Giuseppe Larosa Tue, 12/08/2009 - 06:07
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Hello Senthil,

3G-HWIC is intended to be used as a backup path when primary fails.

So you can use it in DDR scenarios: the cellular interface needs to dial to start to be of use.

Among DDR scenarios there is the dialer-watch feature that can be used to have the cellular interface to dial when specific routes learned by a dynamic routing protocol disappear from routing table a clear sign of a problem over the primary link (that can be connected to another router this makes the difference with backup command for example).

you should be able to use OSPF on a cellular interface like it happens for an ISDN circuit.

But there are some notes:

you should avoid to include OSPF among  the definition of interesting traffic or the cellular interface will stay indefinitively up.

you may need to implement OSPF specific features for on demand circuits



Restrictions for Configuring the 3G HWIC

The following restrictions apply to configuring the Cisco 3G HWICs:

Data connection can be originated only by the 3G HWIC. Remote dial-in is not supported.

Throughput—due to the shared nature of wireless communications, the experienced throughput varies depending on the number of active users or congestion in a given network.

Cellular networks have higher latency compared to wired networks. Latency rates depend on the technology and carrier. Latency may be higher because of network congestion.

Any restrictions that are a part of the terms of service from your carrier.



based on the sentence

Any restrictions that are a part of the terms of service from your carrier.

and on other threads on this you may need to use a GRE tunnel using the cellular line: you may not be able to run OSPF directly over the cellular line.

As reported by others providers can close the connection if they see unexpected IP addresses.

Hope to help



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