Using End Systems with Multiple Local Gateways

Currently, it is not uncommon for an end system to have more than one local gateway. Unfortunately, this is one of the weakest areas of IP routing. It is readily apparent that, when the concept of IP gateways for end systems was being considered by those writing IP protocol stacks, it was not common to have more than one local gateway.

In Figure 5-19, the PC on the Token Ring has two possible gateways to reach 168.71.5.0. Because most PCs running Windows are not usually running a dynamic routing protocol, they are restricted to using a single gateway at a time. In this case, the PC can use either RouterB or RouterC to reach 168.71.5.0—but not both. If RouterA failed while a PC was using it, the ...

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