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Cisco MGX 8850 Routing Switch Command Reference
Release 2.0, Part Number 78-10467-04 Rev C0, October 2001
Chapter5 PNNI Commands
cnfpnni-routing-policy
Syntax Description
-sptEpsilon The shortest path (SPT) epsilon you supply specifies a tolerance in the form of
a percent that can influence wh ic h paths qualify as equal-cost d u ring r o ut e
calculation. A higher tol erance results in a broader ra nge of path cost-values that
can qualify as equal-cos t. If tw o pa ths have very similar adminis tr at ive weights
(AWs), a large enough tolerance eliminates e qu al - co st a s a ro ut in g fac to r
because the routing algorithm r ega rd s t he co s ts as eq u al .
The range of 0–20 for this parameter comes from the ATM Foru m PNNI
specification. However, the percent of toler an ce th at th e numbers dictate is
determined by individual ven dors. Cisco Systems cur re ntly maps the following
percentages for the Cisco MGX 8850 switch:
0: the total AWs along both directi ons of the route must be i de nt ica l.
1-2: the total AWs along both directions of the route must be within 1.06%.
3-4: the total AWs along both directions of the route must be within 3.125%.
5-9: the total AWs along both directions of the route must be within 6.25%.
10-15: the total AWs along both directions of the route must be within 12.5%.
16-20: the total AWs along both directions of the route must be within 25.0%.
Range:0–20
Default: 0, which mean s th e cost of two paths must be iden tical to qualify as
equal-cost
-sptHolddown The interval between two consecutive calcul ations for generating routing tables.
If a network is stable, it may not be n ecessary to generate routing ta bles 10 times
per second. In such a case, you can increase the value to reclaim C PU time
needlessly used to update unchanging routing tables.
Units:100 millisecond increments
Range: 1–600 (0.1–60 seconds)
Default: 1
-bnPathHolddown The minimum interval between con sec utive calculations of routing tables fo r
border nodes. For a stable network, generating the routing tables 10 times a
second may be unnecessary . I f t his case, you c a n inc re ase t he i nt erv a l to s av e the
CPU time spent on updating routing tables that are not changing.
Note The current release does not support complex nodes, so leave this
parameter as is.
Units:100 milliseconds
Range: 2–600 (0.2–60 seconds)
Default: 2