Page 1190 of 1814 MCDN Alternate Routing553-2901-301 Standard 9.00 January 2002The MCDN Alternate Routing feature may be configured for each of the 512different routes.Congestion occurs when channels within the network are not available. Withthe introduction of the MCDN Alternate Routing feature, each entry of a routelist on one node can be configured to take an alternate entry (route) from theroute list of that node (Private Exchange or Central Office), if congestion isencountered.Alternate routing configuration takes place in LD 86, the Electronic SwitchedNetwork (ESN) administration overlay. The option defined for the Step BackOn Congestion (SBOC) prompt determines the type of alternate routingavailable to calls over a particular route.Alternate routing options are:• NRR: no alternate routing is performed. The call receives congestiontreatment.• RRO: re-route at the originating node if a call encounters congestion. Ifcongestion is encountered at a transit node, the call drops back to thepreceding node, so that the preceding node decides if re-routing isrequired.• RRA: re-route the call at any node, whether originating or transit node,when congestion is encountered.The MCDN Alternate Routing feature is triggered at the controlling nodewhen a Call Clearing message (DISCONNECT or RELEASE COMPLETE)is received, and the cause value in the Call Clearing message is supported forthe MCDN Alternate Routing feature. The cause values which activate theMCDN Alternate Routing feature are:• Cause 3 = No route to destination• Cause 27 = Destination is out of service• Cause 34 = No channel/circuit available• Cause 38 = Network out of order• Cause 41 = Temporary failure• Cause 42 = Congestion
