During route computation, APPN determines the optimum route
through a network in the following steps:
- obtains the required route characteristics from the COS database
using the mode name specified in the session request
- determines all possible combinations of transmission groups and
nodes that form a route to the destination database
- the actual characteristics of the Nodes and TGs in these routes are
compared against the COS tables that contain the required
characteristics of the session. A weight is assigned based on how
well the actual characteristics meet the required characteristics.
Where there is no match between actual and required
characteristics, the route containing the node or TG is excluded
from further computation.
- Each possible route is quantified by adding the weights assigned
to the node and TGs in the route. The route with the lowest weight
is the one used for the session.
This attribute is part of the COS tables and specifies the minimum
cost per connect time for a TG. It is represented by a number
between 0 and 255 and is the relative cost of using a TG. The units
for cost-per-connect time are installation-defined and are typically
based on the applicable tariffs of the transmission facility being
used by the TG. The cost-per-connect time values that a network
administrator assigns to the TGs in a network should reflect the
relative expense of each TG as compared to all other TGs in the
network. A value of 0 means that there is no additional cost in
connecting over the TG(as in the case of a non-switched facility).