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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 dsppnni-routing-policy
Display Contents
This section lists the displayed information for each node. The display shows the configuration that
results from cnfpnni-routing-policy.
SPTepsilon This parameter is meaningful primarily for crank ba ck. The epsilon you suppl y
specifies a tolerance in the fo rm of a p e rcen t that can influence which pat hs
qualify as equal-cost during ro ut e ca lc ulation. A higher tolerance resul ts in a
broader range of path cost-values that can qualify as equal-cost. If two paths
have very similar administrative weights (AWs), a large enough tolerance
eliminates equal-cost as a routing f actor because the routing algorithm rega rds
the costs as equal.
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 individu al ve n d or s . Cisco Systems curre nt ly maps the
following percentages for the Cisco MGX 8850 switch:
0: the total AWs along both direc ti on s o f th e p at h must be identical.
1-2: the total AWs along both directions of the path must be within 1.06%
3-4: the total AWs along both directions of the path must be within 3.125%
5-9: the total AWs along both directions of the path must be within 6.25%
10-15: the total AWs along both directions of the path must be within 12.5%
16-20: the total AWs along both directions of the path must be within 25.0%
Range: 0–20
Default: 0, so only i d ent ical path-cost values qu alify as equal-cost
Loadbalance The load balancing rule if any alternative, equal-cost routes exist for a given
call request.
random = requires the lea st overhead due to minimal calculation. Best choic e
when selecting between pat hs th at have similar available bandwidth.
maxbw= requires the most overhead due to ongoing comparison of available
bandwidth on paths. Best choic e whe n se lec ting be twee n pat hs wi th di ssim ila r
or fluctuating bandwidth.
SPT holddown time Minimum time between consecutive calculations that generate routing tables.
Units:100 millisecond increments
Range: 1–600 (0.1–60 seconds)