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Cisco MGX 8850 Routing Switch Command Reference
Release 2.0, Part Number 78-10467-04 Rev C0, October 2001
Chapter 5
PNNI Commands
cnfpnni-routing-policy
cnfpnni-routing-policy
Configure PNNI Routing Policy
—
specify the routing policy parameters.
The cnfpnni-routing-policy command specifies which routing policy values are used during UNI call
setup. Routing policies control PNNI routing for your network.
The cnfpnni-routing-policy command specifies which routing policies are used for:
•
Generating background routing tables
•
Load balancing
•
On-demand routing—applies to crankback or a situation where the node must route a call to a
destination for which no route exists in the pre-computed routing tables
The two dynamic routing protocols are shortest path and on-demand routing.
Background Routing Tables
The background routing tables contain all routes within the peer group. The routes are calculated from
information in the internal data base (IDB). When a topology change affects usable routes within the
peer group, a PNNI topology state packet carries the formation to each node so it can update its IDB.
The background routing tables are updated to reflect the change in routing parameters.
Routing tables are generated (or pre-computed) to support routing based on the shortest path.
•
The administrative weight (AW) background routing table stores the AWs for all routes.
•
The cell transfer delay (CTD) background routing table stores the CTD data for known routes.
•
The cell delay variation (CDV) background routing table stores the CDV data for known routes.
On-demand routing is used if any of the following occur:
•
All pre-computed routing tables are disabled.
•
A route does not appear in the precomputed routing tables.
•
Crankback is enabled within a designated transit list (DTL).
Caution
Poor
routing policies can cripple or even crash a network. You should not change routing policies on
a deployed network unless you have carefully planned the changes and know how the changes can
affect the network.
Cards on Which This Command Runs
PXM45
Syntax
cnfpnni-routing-policy
[-sptEpsilon epsilon]
[-sptHolddown holddown]
[-bnPathHolddown bn-path-holddown]
[-loadBalance {random | maxbw}]
[-onDemand {firstfit | bestfit}]
[-awBgTable {on|off}]
[-ctdBgTable {on|off}]
[-cdvBgTable {on|off}]