alcap and ranap separation

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Date: 31/10/03 UMR 3.0 of 11Confidentiality: Confidential DPC Separation of ALCAP and RANAP

Feature description

DPC Separation for ALCAP and RANAP

Confidentiality: Confidential

Authors: Angelo Ronchi (NEC I)

Revised: Antonio Coricciati (NEC I), Matteo Taglienti (SMC)

Release: UMR 3.0

Version: 1.0Issued: 31 October 2003

Number of pages: 11

History

Version

1.0

Description

First issue





1 Contents

1 Contents..........................................................................................................................2

2 Document Scope .............................................................................................................. 3 2.1 Purpose ......................................................................................................................................3 2.2 Synopsis .....................................................................................................................................3 2.3 References..................................................................................................................................3

3 Overview ......................................................................................................................... 4

4 O & M Parameters and Configuration................................................................................ 5

5 CS RAB assignment .......................................................................................................... 6

6 System Restart.................................................................................................................6 6.1 MSC restart.................................................................................................................................6 6.2 MSC partial restart.......................................................................................................................7 6.3 MGW restart................................................................................................................................7 6.4 RNC restart .................................................................................................................................8 6.5 RNC partial restart ....................................................................................................................... 9

7 Protocol architecture ........................................................................................................ 9

8 VP/VC Basic Configuration .............................................................................................. 10





2 Document Scope

2.1 Purpose

The purpose of this document is to describe the implementation for the separation of DestinationPoint Code (DPC) for RANAP and ALCAP for CS domain.

2.2 Synopsis

This document give an overview of functionality and are also analyzed the System Aspects,Releases compatibility, Functional and Architectural aspects.

2.3 References

[1] TS 25.410 “ UTRAN Iu Interface : General Aspects and Principles ” v3.8.0





3 Overview

Actual configuration (UMR 2.0) of RNC permits an Architecture of CN with common DPC for ALCAPand RANAP for CS Domain, as showed in Figure 1

Figure 1: CN architecture with common DPC for ALCAP and RANAP

At the same time, [1], 3GPP TS 25.410 v3.8.0 mentions :

“For a given MSC, the RNC shall be able to access RANAP and ALCAP either under the same MTP3bdestination point code, or under different point codes”

For this reason from UMR 3.0 the RNC in addition to the common DPC configuration (fig. 1),supports the separation of DPC for RANAP and ALCAP on Iu Interface for CS Domain (Split CN Architecture in Media Gateway –MGW- and MSC Server) Rel ‘4.

The RNC is physically connected only to the MGW (max 1 MGW). MGW and MSC point codes(DPCs) are different. MGW performs the routing messages to the MSC or itself based on theindicated point code (DPC). Signalling bearer of ALCAP is terminated at the MGW. Signalling bearerof RANAP is terminated at the MSC (ATM Cross-connected at the MGW). In addition, the MGWperforms the routing of messages to the SGSN based on the relevant point code (DPC) (ATMCross-connected at MGW).

RNC

MSC

SGSN

Link Group #2 (RANAP Iu-PS)

POINT CODE

(decimal)12801

POINT CODE

(decimal)1275

POINT CODE

(decimal)12930

Link Group #1 (RANAP Iu-CS/Q.AAL2)

RANAP and ALCAP

terminate at the samepoint code (MSC)





RNC MGW

MSC

Server

SGS

N

Link Group #1A

(RANAP Iu-CS)

Link Group #2 (RANAP

Iu-PS)

POINT CODE

(decimal)

12801

POINT CODE

(decimal)

1267

POINT CODE

(decimal)1275

RNC-MSC Server links are ATM

cross-connected at the MGW Link Group #1A

(RANAP Iu-CS)

Link Group #2

(RANAP Iu-PS)

POINT CODE

(decimal)

12930

Link Group #1B

(Q.AAL2)

RNC-SGSN links are ATM

cross-connected at the MGW

Figure 2: CN architecture for the separated DPC for ALCAP and RANAP

The support of this feature allows inter-working with the Core Network implementations supportingthe Rel. 4 architecture of a separated MGW and MSC server, but Rel ‘4 protocols (RANAP-R4,Q.2630.2) are not supported

4 O & M Parameters and ConfigurationIn the separated architecture, the following parameters shall be set to the values of the MGW. Inthe combined architecture, they shall be set to the values of the MSC.

NAME TYPE & RANGE DESCRIPTION

AAL2 end point address

– initial domanin identifier

Type: Octet String

Range: 1-15 digits

0,…,9

This parameters refers to theSP for Q.AAL2 signalling in theCS Domain

AAL2 end point address

– domanin specific part

Type: Octet String

Range: 1-22 hex

(0,…,9,a,…,f)

This parameters refers to theSP for Q.AAL2 signalling in theCS Domain

Destination Point Code (CS)

Type: Octet String

Range: 5-9 digits

0,…,9

This parameters refers to theSP for Q.AAL2 signalling in theCS Domain Destination PointCode

Network Indicator (CS)Type: Integer

Range: 0…3

This parameters refers to theSP for Q.AAL2 signalling in the

CS Domain

Table 1: Parameters for separation of ALCAP and RANAP DPC





Configuration of transport parameters for RNC-MGW connection must be configured and to beused from LMT.

5 CS RAB assignment

During the CS RAB Establishment procedure, upon reception of the RANAP RAB AssignmentRequest message from the CS domain of the CN, the RNC determines the addressing information(NI, DPC) for the node to which the ALCAP signalling shall be sent.

By using O&M parameters, the RNC shall map the NI and DPC values from the “Transport Layer Address” IE included in the RAB Assignment Request message (AAL2 End-point Address -A2EA-).

If there is no mapping found between the A2EA and NI, DPC the RNC shall fail the RAB Assignment procedure.

6 System RestartThe restart sequences are not affected by the different CN architectures. The following behavioursare therefore supported.

6.1 MSC restart

R N CPC= p1

A 2E A = a 1

M G WPC= p2

A 2E A = a 2

M SC ServerPC= p3

RA N A P:RE SE T

(DPC=p1)

RA N A P:RE SE T A CK

(DPC=p3) (DPC=p3)

A L CA P:BL O

(DPC=p2)

A L CA P:BL C

(DPC=p1)

Repeated for thenumb er of locally

blo ck ed A A L2 paths

(DPC=p1)

Release of affected

ALCA P resource

Internal release of allRAN AP/ALCA P resources

Figure 3: MCS restart sequence

When a MSC restarts, it is possible for releasing the AAL2 resources in the MGW. Therefore, when

the RNC receives RANAP : RESET, the RNC releases the AAL2 resources on the Iu Interface locallyand does not initiate any AAL2 reset procedures.





If the MSC does not release the ALCAP resources in the MGW, there is the possibility of mismatchbetween the RNC and the CN.

During the restart, the RNC sends ALCAP : BLO for each locally blocked AAL2 resource. Thissignalling is sent towards the MGW instead of the MSC in case of the split CN architecture

6.2 MSC partial restart

RNC

PC=p1

A2EA=a1

MGW

PC=p2

A2EA=a2

MSC Server

PC=p3

RANAP:RESET RESOURCE

(DPC=p1)

RANAP:RESET RESOURCE ACK

(DPC=p3) (DPC=p3)

(DPC=p1)

Release of ALCAP

resource

Internal release of allRANAP/ALCAP

resources

Figure 4: MSC partial restart sequence

Similar to 6.1, the MSC is responsible for the release of the AAL2 resources in the MGW, thereforethe RNC releases the AAL2 resources locally only.


6.3 MGW restart

Upon reception of the ALCAP: RES, the RNC releases the SCCP connections. Therefore, nomismatch between RNC and CS domain is possible.

During the restart, the RNC releases the SCCP connections, and therefore the NI, DPC of the MSCis used.





RNC

PC=p1

A2EA=a1

MGW

PC=p2

A2EA=a2

MSC Server

PC=p3

ALCAP:RES

(DPC=p1)

SCCP:RLSD

(DPC=p3) (DPC=p3)

SCCP:RLC

(DPC=p1) (DPC=p1)

ALCAP:BLO

(DPC=p2)

Repeated for thenumber of

affected SCCPconnections

ALCAP:RSC

(DPC=p2)

ALCAP:BLC

(DPC=p1)

Repeated for thenumber of locally

blocked AAL2paths

Figure 5: MGW restart sequence

6.4 RNC restart

RNC

PC=p1

A2EA=a1

MGW

PC=p2

A2EA=a2

MSC Server

PC=p3

RANAP:RESET

(DPC=p1)

RANAP:RESET ACK

(DPC=p3) (DPC=p3)

(DPC=p1)

Release of affected

RANAP/ALCAP resource

Figure 6: RNC restart sequence

Upon reception of RANAP Reset, the MSC is responsible for the release of the AAL2 resources inthe MGW. Therefore, the RNC does not send ALCAP: RES to the MGW.






6.5 RNC partial restart

RNC

PC=p1

A2EA=a1

MGW

PC=p2

A2EA=a2

MSC Server

PC=p3

RANAP:RESET RESOURCE

(DPC=p1)

RANAP:RESET RESOURCE ACK

(DPC=p3) (DPC=p3)

(DPC=p1)

Release of affected

RANAP/ALCAP resource

Figure 7: RNC partial restart sequence

Similar to 6.4, upon reception of RANAP Reset Resource, the MSC is responsible for the release ofthe AAL2 resources in the MGW. Therefore, the RNC does not send ALCAP: REL for the affected AAL2 resources.


7 Protocol architecture

The following figures depict the protocol termination points for the split CN architecture. RANAP-CS, RANAP-PS, ALCAP, Iu-CS-UP and Iu-PS-UP are all on separate VCs. There are separate VPsdepending on the terminating node.

RANAP - CS

RANAP

SCCP

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

RANAP

SCCP

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

ATM

L1

RNC MGW MSC

OPC = Self Node

DPC = CN-CS

ATM cross-connect

Figure 8: Protocol termination for RANAP - CS in case of split CN architecture





ALCAP - CS

Q.2630.1

Q.2150.1

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

Q.2630.1

Q.2150.1

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

RNC MGW

OPC = Self Node

DPC = MGW

Figure 9: Protocol termination for ALCAP in case of split CN architecture

RANAP - PS

RANAP

SCCP

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

RANAP

SCCP

MTP-3b

SSCF-NNI

SSCOP

AAL5

ATM

L1

ATM

L1

RNC MGW MSC

OPC = Self Node

DPC = CN-PS

ATM cross-connect

Figure 10: Protocol termination for RANAP - PS in case of split CN architecture

8 VP/VC Basic Configuration

In the following it is possible to compare the difference between actual VP/VC Basic Configuration(UMR 2.0) and that adopted with this feature (UMR 3.0).




Date: 31/10/03 UMR 3.0 of 11

(UMR 2.0)

(UMR 3.0)

There is one VP for RANAP-CS, one VP for ALCAP and Iu-CS-UP, and one VP for RANAP-PS and Iu-PS-UP.

RNC

MSC

SGSN

STM-1

VPI (To MSC) 1 VC Iu CS-UP + 1 VC RANAP CS / ALCAP

VPI (To SGSN) 1 VC RANAP PS + 1 VC Iu PS-UP

VPI (To MSC) 1 VC RANAP CS

RNC

STM-1

MGW

VPI (To MGW) 1 VC ALCAP + 1 VC Iu CS-UP

VPI (To SGSN) 1 VC RANAP PS + 1 VC Iu PS-UP

MSC

SGSN

alcap and ranap separation

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