8-8
Cisco MGX 8850 (PXM1E/PXM45), Cisco MGX 8950, Cisco MGX 8830, and Cisco MGX 8880 Configuration Guide
Release 5.0.10, OL-3845-01 Rev. B0, August 16, 2004
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]
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