5.5 Static and Default Routing
5.5.1 Use of static and default routes
The nature of DDR networks is that routing and some directory services tables must be maintained over idle connections. DDR designers may use a combination of static, dynamic, and snapshot routing techniques to meet design needs. Default routing and remote node spoofing techniques (such as Cisco IOS EZIP) can be used to greatly simplify routing design.

Often the backbone at the NAS (network access server) site will use a fast-converging routing protocol such as OSPF or EIGRP; however, these protocols do not operate easily on the dialer media due to their broadcast and link-state nature. Typically, static routing and/or distance vector routing protocols are selected for the DDR connections. Routing redistribution may be required to support propagation of routing information between the different routing protocols.

A complete discussion of routing redistribution techniques is beyond the scope of this chapter; however, DDR designers do need to develop and verify their routing strategy for each network protocol.