Example of weight computation

The following example illustrates how a class of service is used to assign a weight to an element of a route. This example illustrates what weight is assigned to a TG with default characteristics using the #CONNECT class of service. Default characteristics of a TG are shown in Table 1. Default LINEROW values for the #CONNECT Class of Service are shown in Table 2.

Table 1. Default TG characteristics
TG number	TG1
CAPACITY	8K
COSTBYTE	0
COSTTIME	0
PDELAY	TERRESTR
SECURITY	UNSECURE
UPARM1 UPARM2 UPARM3	128 128 128

Table 2. #CONNECT Class of Service LINEROW values
LINEROW	CAPACITY	COSTBYTE	COSTTIME	PDELAY	SECURITY	Weight
1	4M MAXIMUM	0 0	0 0	MINIMUM NEGLIGIB	UNSECURE MAXIMUM	30
2	56000 MAXIMUM	0 0	0 0	MINIMUM TERRESTR	UNSECURE MAXIMUM	60
3	19200 MAXIMUM	0 0	0 0	MINIMUM TERRESTR	UNSECURE MAXIMUM	90
4	9600 MAXIMUM	0 0	0 0	MINIMUM TERRESTR	UNSECURE MAXIMUM	120
5	19200 MAXIMUM	0 0	0 0	MINIMUM PACKET	UNSECURE MAXIMUM	150
6	9600 MAXIMUM	0 128	0 128	MINIMUM PACKET	UNSECURE MAXIMUM	180
7	4800 MAXIMUM	0 196	0 196	MINIMUM MAXIMUM	UNSECURE MAXIMUM	210
8	MINIMUM MAXIMUM	0 255	0 255	MINIMUM MAXIMUM	UNSECURE MAXIMUM	240

The values shown in Table 2 for capacity, cost per byte, cost per unit of time, propagation delay, security level, and the user-defined characteristics (UPARM1, UPARM2, and UPARM3) represent ranges, with the top value in a LINEROW representing the minimum value and the bottom value in a LINEROW representing the maximum value. In comparing these values with the TG characteristics shown in Table 1, the first match occurs at row 7.

The cost per byte, cost per unit of time, security, and user-defined characteristics are acceptable for all rows. However, the possible LINEROW values for capacity (number of bits per second that the link can transmit data) are MINIMUM, 600, 1200, 2400, 4800, 9600, 14400, 19200, 48000, 56000, 64000, 4M, 16M, and MAXIMUM, and effective capacity is not within the range for rows 1 through 6. The possible values of propagation delay (from lowest to highest) are:

MINIMUM
NEGLIGIB
TERRESTR
PACKET
LONG
MAXIMUM

Propagation delay is not within the range for the first row.

So, the default values for a TG match both rows 7 and 8 of the #CONNECT Class of Service. Row 7 has a weight of 210 and this weight is assigned to this TG for the route being calculated. Row 8 has a weight of 240, but even if it had a lesser weight it would not be used. (It is recommended that you code your rows from least weight to highest weight to ensure that the least weight row is used in the event of multiple matches.)

This TG is used if no other TG is available. If another TG is available, it is used if its weight is less than 210. In the event two or more TGs are equally weighted, one is chosen at random.

If this TG is being considered for part of a route that involves nodes and other TGs, the weight of this TG would be added to the weights of the other TGs and nodes, to produce a total weight for the route.

If the origin or destination of this TG is a virtual node, the weight of the TG is divided by two and the calculated value is used in route calculation.

For an example of how to use the node and TG characteristics to force a route, see Forcing an APPN route in a VTAM network.