Cisco Systems OL-7396-01 Advanced PNNI Configuration

11-29
ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter11 Configuring ATM Routing and PNNI
Advanced PNNI Configuration
Advanced PNNI Configuration
This section describes how to configure advanced PNNI features. The advanced features described in
this section are not required to enable PNNI, but are provided t o tune your network performance.
For additional information about the features described in this section, refer to the Guide to ATM
Technology.
This section includes the following subsections:
•Tuning Route Selection, page 11-29
•Tuning Topology Attributes, page 11-39
•Tuning Protocol Parameters, page 11-49
•Configuring ATM PNNI Statistics Collection, page 11-52
Tuning Route Selection
The tasks described in the following subsections are used to tune the mechanisms by which routes are
selected in your PNNI network.
Configuring Background Route Computation
The ATM switch router supports the following two route selection modes:
•On-demand—A separate route computation is performed each time a SETU P or ADD PARTY
message is received over a User-Network Interface (UNI) or Interim Interswitch Signaling Protocol
(IISP) interface. In this mode, the most recent topology information received by this node is always
used for each setup request.
•Background routes—Call setups are routed using precomputed routing trees. In this mode, multiple
background trees are precomputed for several service categories and quality of service (QoS)
metrics. If no route can be found in the multiple background trees that satisfies the QoS requirements
of a particular call, route selection reverts to on-demand route computa tion.
The background routes mode should be enabled in large networks w here it usually exhibits less stringent
processing requirements and better scalability. Route computation is performed at almost every poll
interval when a significant change in the topology of the network is reported or when significant
threshold changes have occurred since the last route computation.
To configure the background route computation, perform these steps, beginning in glob al configuration
mode:
Command Purpose
Step1 Switch(config)# atm router pnni
Switch(config-atm-router)#
Enters ATM router PNNI mode.
Step2 Switch(config-atm-router)#
background-routes-enable
[insignificant-threshold number] [poll-interval
seconds]
Enables background routes and configures
background route parameters.