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Cisco MGX 8850 Routing Switch Command Reference
Release 2.0, Part Number 78-10467-04 Rev C0, October 2001
Chapter7 SPVC and SVC Commands
addcon
-frame Frame discard: Enter a 1 to enable or a 0 to disable. The default is disabled (0).
-mc Maximum cost (maxcost): a value that creates a priority for the connection route .
The switch can select a route o nly if the cost does not exceed maxcost. The ran ge
for maxcost is 0–2147483647. If you do not speci fy maxcost, the conn ect ion ha s
the highest routing priorit y by de fau lt. T herefor e, the maxcost parameter lets you
lower the routing priority of a connection. Note the following effects of values
in the maxcost rage:
•To assign the highest priority to an SPVC based on cost (any path is
acceptable), enter 2147483647. You can achieve the s a m e re sul t by n o t
specifying maxcost at all, in which case the cost appears as a –1 in the
dspcon output. (You cannot enter a –1 for either maxcost in addcon or to
the cnfpnni-intf command, but dis p la y commands can show u ns p e c ifie d
values a s –1.).
•Enter a 0 for optimal (or least expensive) path.
•For any non-zero maxcost, the switch assigns a path if the total cost for all
links does not exceed maxcost.
Although maxcost applies to an individual connection, routing costs
substantially depend on a cost-per-link that you specify at every PNNI logical
port in the network. The applicab le P N NI co m ma nd is cnfpnni-intf. (See the
description of the administrative weight parameter for cnfpnni-intf in the
chapter, “PNNI Commands.”
The cost of a route is as follows:
routing cost=sum of all costs-per-link
where:
•The cost-per-link has been specified through cnfpnni-intf at the egress of
each logical port under PNNI control throughout the network. The impact
of cost-per-link is cumulative, n o t j us t lo ca l.
•Each link has two egress points: one going to the far endpoint, and one in
the return direction. The cost- pe r-lin k can d iffer in e ach direction, so the
switch adds the cost-per-link i n each egress instead multiply ing cost by two.
The cost-per-link applies to a ll connections of a particu lar service type on a port.
For example, the cost-per-link is the sam e for all VBR.1 connections th at PNNI
controls on a port, and this cost can differ from all UBR.1 connections on the
same port. Alternatively, you can use cnfpnni-intf to make the cost-per-l ink the
same for all service types.
To illustrate by examining a four-li nk r o ut e:
1. You s pe ci f y a ma xcost of 100000.
2. A potential route has four links for a total of eight egress points (four going
to the endpoint and four coming back).
3. The cost-per-link at 6 ports is 5040 (the default) and 10000 at 2 ports.
The PXM45 would use the route because the result ing co st of 50 240 is less th an
the maxcost of 100000.