Overview
8
Fault Tolerance and
Isolation
A single large network has several problems relating to faults. Two are
listed below:
1.
If the network fails all users lose connectivity.
2.
Because of the network size, it may take a long time to find the fault.
Figure 9 shows the failure of a simple network.
When bridges are used, a network becomes much more fault tolerant. This
is especially true if a backbone network topology is used.
With a cascaded network, a fault will split the network into two disjointed
parts. This is shown in Figure 10.
In a backbone network two possibilities arise. If the backbone fails, the
network will be partitioned into as many partitions as there are networks
attached to the backbone. However, in the more common case of a failure
within one of the attached networks, only that network is affected, while
all other networks can still communicate with each other. This is shown in
Figure 11.
Figure 9: Failure on a Simple
Network
Figure 10: Failure of a Cascaded
Bridged Network
