HP 200 Series Services And Applications page 199

setup delays or other problems that can occur with switched backup
schemes.
Flexible networking options. Although the permanent alternate path
selected for wide-area networks is typically a leased line, it could be
a public switched service such as X.25, frame relay, or SMDS. In
addition, there is a wide range of link speeds from which to choose.
Performance. Better throughput and response times for traffic (if
any) between sites A and C (in figure 1) are easily achieved.
Coterminus Circuits
Another way to establish an alternate path is to create a circuit group with
two or more coterminous circuits. A circuit group is a logical structure that
contains one or more circuits. Coterminous circuits are simply circuits that
have common starting points and common end points.
Consider the network in figure 2. Two coterminous circuits are used to
connect routers A and B. Both circuits have been configured as members of
a single circuit group on each router. The forwarding process within each
redirector directs traffic to circuit groups. The forwarders are not aware of
the lower circuit-level detail. Thus, each router in figure 2 has one route to
the LAN attached to the other router. However, data is routed on both
circuits in a load-sharing fashion.
a
Figure 2. Interconnecting Routers with Coterminus Circuits
Improving Network Availability
Circuit Group
Circuit 1
b
Circuit 2
Coterminus Circuits
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