Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-26
Network Routing Table (NRT) and Multiple Path
Table (MPT)
$NCP sends routing information to the $NCPs at its neighbor nodes at the following
times:
•
As soon as $NCP becomes aware of a change in the network, such as a line going
up or down or a node being added or deleted.
•
During a regular maps exchange. (Maps exchanges are described in Regular
Maps Exchanges on page 18-27.)
Immediate Network Updates
If the communications line between nodes \C and \D in Figure 18-7 were to fail, for
example, both nodes \C and \D would immediately notify the neighbor nodes \A, \B,
and \E. Nodes that are not immediate neighbors would be notified during a regular
maps exchange. This same neighbor-informing scheme is used when a
communications line becomes available or when a new node is added to the network.
For a multi-line path, the procedure is the same as that just described above, with one
exception: a line-ready or a line-not-ready condition can cause a change in a path TF
without causing a change in the best-path route. For a multi-CPU path, the procedure
is the same as that described for single-line paths.
Figure 18-7. $NCP Exchange of Network Change Information
017CDT .CDD
Node \A
Node \C
Node \B
Node \D
Node \E
Informs
Neighbor
of Failure
Informs
Neighbor
of Failure
Informs
Neighbor
of Failure
Line Failure
Informs
Neighbor
of Failure