HP 200 Series Services And Applications page 206

Improving Network Availability
Circuit Group Considerations
Figure 4. Routing Using Switched Network Services
Backup Circuits
Switched circuits are often the most cost-effective alternative to a meshed
network (a network using permanent alternate paths) for improving
availability. Switched services may be used to back up private leased lines or
packet-switching networks. When compared to leased-line CSUs/DSUs with
dial backup capability, the HP routers' switched backup function provides
more flexibility in selecting the type of switched circuit.
Figure 5. Backup and Primary Circuits in a Circuit Group
3-12
a
b
CIRCUIT
SWITCHING
NETWORK
c
Circuit Group
Primary Circuit
DSU/CSU
a
Terminal
Adapter
Backup Circuit
e
d
Leased Line
to Remote
DSU/CSU
To Switched
Network