Nortel Networks NN10029-111 manual Reliability and fault tolerance

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26 Overview	Nortel Networks Confidential

Reliability and fault tolerance

The SIP Application Module provides reliability and fault tolerance through multiple SIP Application Modules deployed in an N+M active-standby configuration.

Note: The supported active/standby configurations include:

•a 1+1 configuration (one active plus one standby server), which is the most basic reliable configuration

•an N+M configuration of up to four servers (the sum of N plus M should not exceed 4)

—a 2+1 (2 active and one standby)

—2+2 configuration

—3+1 configuration

To accomplish this, all the servers in a reliability group are configured with the same set of NSDs. This gives the standby server the information it needs in case an active server fails. Each server in the group transmits messages indicating its current state. Other servers respond with their current states, including the NSD activated on them.

An initializing server configures itself with one of any inactive NSDs. If all NSDs are active, the initializing server becomes the standby. This prevents conflicts where more than one server is activating simultaneously.

Before activating, the server determines whether it is isolated from critical network resources defined through provisioning. If any of the resources cannot be reached, the server cannot activate and raises an alarm. The alarm clears when the resources become available.

When there are two or more active servers, the group is called a cluster. You can configure both the N+M strategy and the cluster at the Transport Management tab in step 22 in the Configuration chapter.

When one of the active SIP Application Modules fails, the passive Module takes over the IP address. The passive Module has now become active and assumes the responsibilities of the failed Module. When this occurs, any sessions already in the active state remain up. This means that calls that have already been established continue and the parties maintain voice path. Any future requests during that session, however, fail (for example, Hold, Retrieve, and Web Pushes) since the session information is no longer available. Any sessions that were not in the active state before the failover are lost. The originating clients of

NN10029-111 Standard MCP 1.1 FP1 (02.02) April 2003

Copyright © 2003, Nortel Networks

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Contents MCP SIP Application Module Page Overview How this chapter is organizedOverview Functional descriptionBack-to-Back User Agent service UserA Agent Client Internal ProtocolNetwork configuration BigMart.com BiggerMart.comInterfaces Public networkPCP ProtocolsSQL Services and features HardwareRouting and Translation services Foreign termination Telephony routing Call Transfer serviceLocal termination Relationship between Telephony routing stages SIP Aliases Multiple Route Termination Interworking services Discriminator service Call Processing LanguageAuthentication services Privacy Control serviceService package enforcement Bearer Path ControlConverged PC service Network/Address Hiding service Enterprise Clients Notification support Voicemail server interoperability and MWI Instant MessagingPresence Nortel Networks Confidential Overview Registration-static and dynamic Network address book Overload controlReliability and fault tolerance Manual failover OAM&P strategy Upgrades Updating the SIP Application Module softwareUpdating the Application Module from the menu tree Updating the SIP Application Module from the pull-down menu Load list for updating Progress of update Page Alarm clearing procedures Procedure 1 Clearing the SLE701 Slee Health Monitor alarmProcedure 2 Clearing the SMDI101 alarm Configuration Configuration Nortel Networks Confidential Displaying help text Procedure 1 Adding a component Adding a componentAdding a component Configuration window top half Adding Services Progress dialog box Configuring the SIP Application Module tabs Application Server tab field descriptions Sheet 2 Field Value DescriptionConfiguration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential URL Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Completing the Database Base tab fields DNS SRV Locate User Svc tab field descriptions Sheet 2 Completing the Data Synchronization tab fieldsConfiguration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Completing the Local Accounting Manager tab fields Completing the In Memory Database tab fields Configuration Nortel Networks Confidential Memory Database tab field descriptions Sheet 2 Completing the Location Service tab fields Location Service tab field descriptions Sheet 2 Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Server.blade.host.label for Privatestaticaddress whose valueCompleting the Server Subscription tab fields Addrsip Porthttp Portprotocol Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential SipFwdAdapter tab field descriptions Sheet 2 Completing the Transport Management tab fields Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Configuration Nortel Networks Confidential Nortel Networks Confidential Configuration Figure above Nortel Networks Confidential Configuration Transport Management tab subfields, cont’d Transport Management tab subfield descriptions Active-standby server group configuration Nortel Networks Confidential Configuration UDP/TCP/SSL Config values Parameter Value Description Additional SIP TCF Base tab configuration informationTCF Config details ExampleInvite Timer parameter Retransmission Off parameterCheck Mandatory Headers parameter Add Defaults parameterTime Transaction parameter Accounting management Page Performance management Page Security and Administration SecurityPage Appendix a Basic call flows Voice plus videoClient-to-client voice plus video diagram Client-to-client voice plus video call flow Application Client a Module Client BCall transfer to client diagram Client a Client C Client B Call transferCall transfer blind to client call flow Application Client a Module Client B Client CAppendix a Basic call flows Nortel Networks Confidential Failed call transfer call flow Appendix a Basic call flows Nortel Networks Confidential Authentication Authentication diagramAuthentication call flow Application Client a Module DatabaseNortel Networks Confidential Appendix a Basic call flows Page Page Page Page MCP SIP Application Module