This feature sends SIP MESSAGE requests to instruct superfluous session removal .

For an architectural view of co-ordinating signalling anchors refer to Shared ATU-STI.

Feature cheat sheet

B2BUA Instance SAS Support Originating / Terminating Point in Session Plan Network Operator Data Subscriber Data Stateful or Stateless POJO Feature or SBB Feature

SCC

Yes

Originating and Terminating

SipMidSession_PartyRequest and SipEndSession

Yes

No

Stateless

POJO

Prerequisite Features

Network Operator Data

Network configuration is stored in a JSLEE profile table named SCCCoordinateSignallingAnchorsConfigProfileTable.

Parameter Type Default Value Description

CoordinateSessionsDelay

int

2000

Time in milliseconds to wait between receiving the access transfer ACK and sending out SIP MESSAGEs to remove superfluous sessions.

Session input variables

Variable Type Description 
ASURI

String

The URI of this SCC node loaded by SCCDetermineSessionType

 
AccessTransferACKed

boolean

Set by SCCProcessHandoverInsideAnchor to indicate that the Access Transfer INVITE has been ACK’d.

 
SuperfluousSessions

Set<TrackedSession>

The set of TrackedSessions that will be removed. A SIP MESSAGE is sent for each entry. Set by SCCDetermineTransferableSet.

Session output variables

None.

Statistics

SCCCoordinateSignallingAnchors statistics are tracked by the sentinel.volte.sip SBB and can be found under the following parameter set in REM:
SLEE-Usage → sentinel.volte.sip service → sentinel.volte.sip SBB → feature → SCCCoordinateSignallingAnchors
or with rhino-stats:
"SLEE-Usage.Services.ServiceID[name=sentinel.volte.sip,vendor=OpenCloud,version=4.1].SbbID[name=sentinel.volte.sip,vendor=OpenCloud,version=4.1].feature.SCCCoordinateSignallingAnchors"

Name Description 
Started

Incremented each time the feature runs

 
FailedToStart

Incremented when a fatal error occurs before feature execution

 
IssuedWarning

Incremented when a non-fatal error occurs during feature execution

 
FailedDuringExecution

Incremented when a fatal error occurs during feature execution

 
TimedOut

Incremented when feature execution does not complete within a reasonable time frame

 
TimerStarted

Incremented when the feature starts the timer

 
TimerFired

Incremented when the feature receives the timer event

 
TimerCanceled

Incremented when the feature cancels the timer

 
SentSuperfluousSessionMessage

Incremented when the feature sends a SIP MESSAGE request to a remote node to remove a superfluous session

 
SentSuperfluousSessionMessageInternally

Incremented when the feature sends a SIP MESSAGE event internally to remove a superfluous session

 
CouldNotFindInternalTargetSession

Incremented when the target session could not be found

Behaviour

The feature is first triggered when an Access Transfer is completed by receiving an ACK for the handover INVITE. When the ACK is received, the SCCProcessHandoverInsideAnchor feature sets the session state flag AccessTransferACKed. When that flag is TRUE, this feature will arm a timer with the value in CoordinateSessionsDelay.

Then when either the timer fires, or the session is ending the feature will construct a SIP MESSAGE for each TrackedSession in SuperfluousSessions. These MESSAGEs are sent to trigger SCCRemoveSuperfluousSession on the node in control of those sessions.

The MESSAGE will have the following headers set:

Header Name Header Value 
`RequestURI`

The ASURI of the TrackedSession

 
`From`

The ASURI of this node from Session State

 
`To`

The ASURI of the TrackedSession

 
`Target-Dialog`

The EstablishedDialogID of the TrackedSession

 
bxref:oc-access-transfer-procedure-header[OC-Access-Transfer-Procedure]

Remove-Superfluous

 
`P-Asserted-Identity`

The ASURI of this node from Session State
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Sentinel VoLTE Version 4.1