Cabletron Systems SmartSwitch 04-0053-01 User Manual

Also see for SmartSwitch 9A100: User guide Upgrade instructions Installation and setup guide

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Cabletron Systems SmartSwitch 04-0053-01 User Manual Manual pdf 63 page image

SmartSwitch ATM User Guide 4-7Routing Route MetricsCaution Remember that while some special network configurations may require theTimeoutValue to be zero (0), setting TimeoutValue to less than three secondsmay cause a UNI route to fail unnecessarily. For this reason, care should betaken when setting the TimeoutValue to less than three seconds.4.4 ROUTE METRICSRoute metrics are assigned to routes using a metric tag (one of the input parameters for add atmroute). The metric tagspecifies a particular pair of incoming and outgoing metrics contained within a list of metrics. Metrics are created usingthe add pnnimetric command (whether PNNI, IISP, or UNI routes). Each metric pair specifies a set of values thatdescribe a route’s Service Category, cell rates, bandwidth, and administrative weight. Locally, metric values determinethe behavior of the link. Within PNNI networks, PNNI’s Generic Call Admission Control (GCAC) assesses metricswhen establishing calls.4.4.1 Administrative WeightsThe administrative weight (AdminWt parameter) of a metric allows you to control the use of a route for call set ups. Bydefault, a metric assigns the lowest value (5040) to the AdminWt parameter. Values less than 5040 (for example 500)are considered to have greater administrative weight. Among parallel routes, the route with the greatest administrativeweight is seen as the preferred route; subsequently, most calls are set up through that route. Other parallel routes withlower administrative weights are used as “backup” routes These backup routes will be used only if the route with thegreatest administrative weight is either out of bandwidth or down.4.4.2 Creating Route MetricsThe following section describes how to create a route metric and assign it to a route.Note For a complete description of all pnnimetric parameters, see the SmartSwitchATM Switch Reference Manual.In the following example, a metric pair is created (with metric tag of 9), which specifies CBR as the Service Category,administrative weight of 200, Max Cell Rate of 1000 cells per second, and an Available Cell Rate of 750 cells persecond.Note The default value NotUsed that appears in the add pnnimetric command means“If no value is specified for the parameter, the parameter is not used within themetric.” It does NOT mean that the parameter does not accept values.