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TAC03012_G Ed 02 1 2009 Alcatel-Lucent., All rights reserved

Alcatel-Lucent University Antwerp 1

University

ISAM Voice Operator

Managed with 5520 AMS

Section G: Redundancy

Alcatel-Lucent University Antwerp

University

During class please switch off your mobile, pager or other that may interrupt.


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Course objectives

At the end of this section, you will be able to

Understand MEGACO ISAM Voice Redundancy


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Table of contents

MEGACO ISAM Voice Redundancy . . . . . 4


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Alcatel-Lucent University Antwerp 4

University

MEGACO ISAM Voice Redundancy


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NVPS 1+1 Redundancy

Both configuration data (including CDE files) and dynamicdata are synchronized with the redundant board

The maximum data synchronization interval is 60sRedundant NVPS must be in adjacent slots (odd+even)

For FD shelf, the slots of NTIO and NTB don t support NVPS

NT sees difference through LT Protection Group status

Only active NVPS can be managed by AMS


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NVPS Hot Switch Over (HSO)

ISAM Voice supports NVPS hot switch, which means:POTS/ISDN Established voice calls are not lost. Voice flows arebriefly interrupted although the user does not perceive this

disruption.POTS/ISDN Calls being established during HSO process are lostPOTS/ISDN Call releases initiated during the HSO process can bedelayed no longer than 2-3 seconds after HSO startH.248 connection is kept alive

MGC is not aware of the NVPS switchoverSame address for H.248 is held between active NVPS and standby NVPSWhen switchover happens, the newly active NVPS will send GARP for

signaling IP/voice IP

The ISDN signaling gateway interface is kept alive (SIGTRAN itf.)The XLES link between NVPS and POTS/ISDN boards is kept alive


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Triggers for NVPS Switch Over

Criteria for NVPS to be activeThe NVPS will be active if its planned on the NT. The other NVPS

board would remain passive standby.The active NVPS board should be plugged in an odd slot

Triggers for Switch OverFatal error (causing a restart) occurs on the active NVPS

Active NVPS is pulled out

Lock/Unplan/Restart the active NVPS

Operator sends the switch over command to active NVPS

Uplink failure between NT and NVPS


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Control Interface with MGC Heart Beat

Direction MGC to MGMGC will send heart beat messages to ISAM Voice periodically.ISAM Voice will self-study the time interval of the heart beat messagesand update it if any change. This time interval will be treated as heartbeat period.If MG has not received any message from MGC during the continuous 7times of heart beat period, ISAM Voice will judge that MGC is failed.

Direction MG to MGCISAM Voice will send heart beat messages to MGC timely. The heartbeat period is defined in CDE file.MGC will give Reply to ISAM Voice when receiving the MG heart beatmessage.In the condition ISAM Voice MG has not received Reply from MGC, ISAMVoice will resend the heart beat message for 7 times (currently timeinterval is about 2s), if still not receive Reply from MGC, ISAM Voice willjudge that MGC is failed.

> MGC to MG: the heart beat message is a AuditValue command to ROOT termination with NULLparameter.

> MG to MGC: the heart beat message is a Notify command with it package.


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Control Interface with MGC Process After MGC failure

Process After MGC failureIf there is no secondary MGC, ISAM Voice will periodically try toregister again to the failed MGC.

If there is a secondary MGC, ISAM Voice will try to register to thisMGC. If no response, then he will try again to register to theprimary MGC. If still no response, then to the secondary MGC,etc If the ISAM Voice is unable to connect to an MGC within 10minutes (configurable), it will release all its established RTPpaths.If the ISAM Voice connects to an MGC, then the normalregistration process takes place between MGC and ISAM Voice.If the ISAM Voice has established connection with the secondary

MGC, and the primary MGC has recovered, ISAM Voice will notswitch off from the secondary one to the primary one.

> To a failed primary MGC, ISAM Voice will register through a ServiceChange command with therestart method parameter.

> To a secondary MGC, ISAM Voice will register through a ServiceChange command with thefailover method parameter.


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Control Interface with MGC MGC/MG Association

The MG may register in one of two ways:Announce its initial presence.

Indicate that it was commanded by MGC to change its association

MGC Association failureMG detects the MGC Association failure through the heart beatmechanism described before.

If MG detects the failure of MGC, it attempts to contact the nextMGC on its pre -provisioned list.

MGC switch over (handoff)When MGC encounters a failure condition, it may direct the MGto a specific secondary MGC.

> The MG may register to announce its initial presence with Method = Restart, Reason = cold/warm

> The MG may register to indicate that it was commanded by MGC to change its association with Method =Handoff, Reason = MGC Directed Change

> If MG detects the failure of MGC, it sends a ServiceChange message with a Failover method and a "MGC

Impending Failure" reason. When contacting its previously controlling MGC, the MG sends the ServiceChangemessage with restart" method.

> If an MG fails, but is capable of sending a message to the MGC, it sends a ServiceChange with an appropriatemethod (Graceful or Forced) and specifies the Root TerminationID. When it returns to service, it sends aServiceChange with a "Restart" ServiceChangeMethod.

> When MGC encounters failure condition, it sends a ServiceChange command with a ServiceChangeMethod ofHandoff, a ServiceChangeReason of 903 (MGC Directed Change) and the address of the new MGC in theServiceChangeMgcID parameter.

> When MG receive hand-off from MGC, it then sends a ServiceChange Command to the specified MGC with aserviceChangeMethod of Handoff and a ServiceChangeReason of 903 (MGC Directed Change).

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6. Tac03012 g Ho Ed02 p04 Isam Voice Redundancy Ce