HP 600 Series, Services And Applications

Page: 221 / 316

Figure 14. Packet-Switching Network with Circuit-Switching Backup
The network in figure 14 is set up as follows:
Connections to the packet-switching network are configured in a
single subnet using either RIP or OSPF. OSPF is preferred since it
detects failures and switches around failures faster than RIP.
Connections to the circuit-switching network are configured in a
single subnet (a different subnet than the one used for the packet-
switching network).
Router D (R
d
) is the central site from the perspective of the dial-
backup scheme. R
a
and R
c
have static routes to each of the other
Ethernets; R
d
is the next hop for all of the static routes to the remote
Ethernet networks. The point-to-point circuit between R
b
and R
d
has
been installed to provide a backup path in the envent of a failure in
R
d
’s packet-switching access circuit. A new feature in the next
HP router software release—conditional static routes—allows you
to define a new type of static routeand removes the need for the
point-to-point circuit.
b
a
c
d
Packet
Switching
Network
Circuit
Switching
Network
A
p
p
li
c
a
ti
o
n
N
o
te
s
/
C
a
s
e
S
tu
d
ie
s
3
Improving Network Availability
Sample Networks
3-27