Specifications

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Cisco MGX 8800/8900 Series Software Configuration Guide
Release 5.1, Part Number OL-6482-01, Rev. A0, January 25, 2005
Chapter 8 Managing PNNI Nodes and PNNI Routing
Managing PNNI Nodes
You can use the cnfpnni-routing-policy command to control which SPTs are created, how often they
are updated, and other SPT related features. To display the current routing policies for a node, enter the
dsppnni-routing-policy command as follows:
M8830_CH.1.PXM.a > dsppnni-routing-policy
SPT epsilon......... 0 Load balance........ random
SPT holddown time... 1 On demand routing... first fit
bn path holddown time 2 AW Background Table on
CTD Background Table on CDV Background Table off
To configure the SPT routing policies, enter the cnfpnni-routing-policy command as follows:
mgx8830a.1.PXM.a > cnfpnni-routing-policy [-sptEpsilon] [-sptHolddown] [-bnPathHolddown]
[-loadBalance] [-onDemand] [-awBgTable] [-ctdBgTable] [-cdvBgTable]
Table 8-3 lists the parameter descriptions for the cnfpnni-routing-policy command.
Table 8-3 Parameters for cnfpnni-routing-policy Command
Parameter Description
-sptEpsilon The SPT epsilon allows you to specify a percentage range in which shortest path
routes to a particular destination are considered equal. For example, you can
specify that all routes within 6.25% of the lowest cost route are to be considered
equal and considered for placement in the appropriate SPT.
The range of 0-20 for this parameter comes from the ATM Forum PNNI
specification. However, the percentage applied to this range is determined by
individual vendors. Cisco Systems currently maps this range to percentages as
follows:
• 0 = The routing metric (which is AW, CTD, or CDV) value for all SPT
routes to a particular destination must be identical.
• 1-2 = The SPT considers routes within 1.06% of the shortest path to be
equal.
• 3-4 = The SPT considers routes within 3.125% of the shortest path to be
equal.
• 5-9 = The SPT considers routes within 6.25% of the shortest path to be
equal.
• 10-15 = The SPT considers routes within 12.5% of the shortest path to be
equal.
• 16-20 = The SPT considers routes within 25.0% of the shortest path to be
equal.
Default: 0
-sptHolddown The SPT holddown timer defines the node’s minimum time interval between
two consecutive calculations of the SPTs. If a network is stable, it may not be
necessary to generate routing tables 10 times per second. In such a case, you
can increase the holddown timer value to reclaim CPU time needlessly spent on
updating unchanging routing tables.
Units: 100 millisecond increments
Range: 1-600 (0.1-60 seconds)
Default: 1