Cisco Systems Cisco MGX 8850 - page 331

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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
-loadBalance The PNNI routing protocol relies on the load balance policy whe n it determines
that the routes to a destinatio n have e qu al cost. (PNNI determines rou tes to b e
identical according to the metrics in the AW, CDV, or CTD routing table.) Note
that the SPT epsilon value can be a f act or w h en PN N I cal cu lat es cos t.
The choice for load bala nc ing is “random” or “maxbw.” Type the entire word .
With “random” load balancing, PNNI randomly chooses between the equal cost
routes. This rule require s le ss computational overhe ad.
With “maxbw” load balancing, P N N I sele cts the route with more availa bl e
bandwidth when it chooses between equal cost routes. This rule has more
overhead due to ongoing comparison of available bandwidth on the routes.
Default: no default
-onDemand On-demand routing applies to crankback or a situation where the node must
route a call to a destination for whi ch no rout e exi sts in the pre- comput ed routi ng
tables. The on-demand policy is either “firstfit” and “bestfit.”
With firstfit (the default), PNNI selects the first route to the destination. This
approach minimizes search time but m a y n o t res u l t i n t h e b est rou te.
With bestfit, PNNI selects a route based on:
•The route with the lowes t cost (see AW in the cnfpnni-intf description and
maxcost in the addcon description because th ese pa rameters are closely
related).
•Link verification.
•Path constraint checks.
•Avoidance of blocked nodes and links.
•Checking limits in the desig nat ed t ra nsi t l ist (DTL).
With bestfit, PNNI selects the optimum route but entails greater computing
overhead. The search-time depends on the density and complexity of the
network.
Default: firstfit
-awBgTable Enable or disable the background routing table for AW.
on: The background routing table of AW is enabled.
off: The background routing table of AW is disabled.
Default: on