AAL2 Slide

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AAL Type 2 Signalling Protocol (AAL2SIG)

Switching Core Network Signalling

M14 / U4


Nokia Siemens Networks Academy

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Document change history

Date Version Name Change comment

18.2.08 1 Gatot Mardianto M14/U4 upgrade from M13


Functionality

•AAL type 2 signalling (AAL2SIG) protocol provides the signalling capability to establish, release and maintain AAL type 2 point to point connections across series of ATM VCCs that carry AAL type 2 links.

•These services are accessible via the AAL type 2 served user service access point (A2SU-SAP).

•The AAL type 2 signalling protocol also provides maintenance functions associated with AAL type 2 signalling.

•AAL type 2 signalling is defined by ITU-T Q.2630 recommendation.

•M14/U4 implements Q.2630.2 (Capability Set 2)


Protocol stacks

•AAL2SIG can be run over 2 different protocol stacks– MTP3b/SAAL/ATM : used in IuCs, Nb

– SAAL/ATM : used in Iub

AAL5

AAL2SIG (Q.2630.2)SSCF-UNI

SSCOPAAL5

AAL2SIG (Q.2630.2)

MTP3SSCF-NNI

SSCOP

IuCS/Nb Iub


Protocol Structure for Iu-CS

TransportNetworkLayer

RadioNetworkLayer RANAP Iu User Plane

Protocol

AAL2

ATM

Control Plane

Transport NetworkControl Plane

User Plane

Physical Transmission layer

AAL5

SCCP

MTP3

SSCF-NNI

SSCOP

AAL5

Q.2630.2

MTP3

SSCF-NNI

SSCOP

Transport NetworkUser Plane



TransportNetworkLayer

RadioNetworkLayer

Q.2630.2

NBAP

DC

H F

P

AAL2



ATM

Transport NetworkControl Plane

Physical Transmission layer

AAL5

SSCF-UNISSCOP

AAL5

Q.2150.2

SSCF-UNISSCOP

RA

CH

FP

FA

CH

FP

PC

H F

P

DS

CH

FP

CP

CH

FP

User PlaneControl Plane

Protocol Structure for Iub


ATM Adaptation Layer and Supported Traffic

Typical

Use

Voice Video

Voice(silence removed)

Audio

Data

IP

Frame relay

Data

SMDS

AAL AAL1 AAL2 AAL5 AAL3/4

Connection Oriented Connectionless

Synchronised Not Synchronised

Constant VariableBit Rate

Source & Dest.

Connection

ATM Layer

Physical Layer

A B C D

ATM Service Classes


AAL5

PADDING, variable length to fill the 48-byte ATM cell

AAL5 PACKET, fixed header, variable length payload

ATM CELL, 5-byte header + 48-byte payload

AAL5 Packet Data Unit

USER DATA - Variable length 1 - 65 535 bytes

PAYLOAD = N x 48 BYTES

AAL5 Packet Data Unit

USER DATA - Variable length 1 - 65 535 bytes

AAL5header

ATM cell 1 ATM cell 2………... ………..ATM cell n

Suit for data which no

timing request

between Tx and Rx


AAL2

OFFSET, 1 byte (indicates where the next AAL2 PDU starts)

AAL PACKET, fixed header, payload

ATM CELL, 5-byte header + 48-byte payload

String of AAL Packet Data Units

1 2 3 4

AALheader

ATM CELLHEADER 1 2 3 4

ATM cell

Transmission pathVirtual PathVirtual Channel (VC)ATM Cell

User Layer

ATM Adaptation Layer

ATM Layer

Suit for delay sensitive application


Functional architecture of AAL type 2 signalling

T11104330-99

AAL type 2switch

A2SU-SAP A2SU-SAPL

M-S

AP

LM

-SA

P

LM

-SA

P

Lay

erm

anag

emen

t

Lay

erm

anag

emen

t

Lay

erm

anag

emen

t

AAL type 2

Signalling message

AAL type 2

Signalling message

(Note)

GST-SAP GST-SAP GST-SAP GST-SAP

Signalling transport(e.g. MTP3b + NNI-SAAL, UNI-SAAL, SSCOP, ...)

Signalling transport(e.g. MTP3b + NNI-SAAL, UNI-SAAL, SSCOP, ...)

AAL type 2service endpoint

AAL type 2service endpoint

AAL type 2served user

Signallingtransportconverter




AAL type 2served user

Protocolentity

Protocolentity

Protocolentity

Protocolentity

Nodalfunction

Nodalfunction

Nodalfunction

AAL type 2signalling entity



(Note) (Note) (Note)

NOTE – In every AAL type 2 node, a signalling transport converter instance is associated with each AAL type 2 signalling transport.


AAL type 2 signalling protocol entities

•Outgoing protocol procedures provide the mechanism to initiate an AAL type 2 connection request and also release of AAL type 2 connection.

•Incoming protocol procedures are applied when a request for an AAL type 2 connection is received from the peer entity and also provide release of AAL2 type 2 connection.

•Maintenance protocol procedures provide mechanisms to align the status of AAL type 2 resources at two adjacent AAL type 2 nodes and the procedures to block and unblock an AAL type 2 path.

•The nodal function provides the bridge between incoming and outgoing protocol entities, perform the routing functionality and keeps track of the AAL type 2 resources.


AAL type 2 signalling protocol message format

Signalling association identifier has fixed size field of 4 octets.

When it is used as destination signalling association identifier and has value unknown then field is set to ‘0’.

If it is used as originating signalling association identifier, it can not have value ‘0’.


AAL type 2 message identifiers


Compatibility table for message and parameter

a) Send notification indicator

0 Do not send notification

1 Send notification

a) Instructor indicator

00 Pass on message or parameter

01 Discard parameter

10 Discard message

11 Release connection


AAL type 2 parameter format


Parameters of AAL type 2 signalling messages (1)


Parameters of AAL type 2 signalling messages (2)


Identifiers of the AAL type 2 message parametersAAL type 2 parameter Acronym Identifier

Cause CAU 00000001

Connection Element Identifier CEID 00000010

Destination E.164 Service Endpoint Address ESEA 00000011

Destination NSAP Service Endpoint Address NSEA 00000100

Link Characteristics LC 00000101

Modify Support for Link Characteristics MSLC 00001110

Modify Support for Service Specific Information MSSSI 00001111

Origination Signalling Association Identifier OSAID 00000110

Path Type PT 00010000

Preferred Link Characteristics PLC 00010001

Preferred Service Specific Information (Audio Extended) PSSAIE 00010010

Preferred Service Specific Information (Multirate Extended) PSSIME 00010011

Served User Correlation ID SUCI 00010100

Served User Generated Reference SUGR 00000111

Served User Transport SUT 00001000

Service Specific Information (Audio Extended) SSIAE 00010110

Service Specific Information (Audio) SSIA 00001001

Service Specific Information (Multirate Extended) SSIME 00010111

Service Specific Information (Multirate) SSIM 00001010

Service Specific Information (SAR- Assured) SSISA 00001011

Service Specific Information (SAR – Unassured) SSISU 00001100

Test Connection Indicator TCI 00001101


Explanation of parameters

Cause (CAU)• Gives the reason of an operational error• Describes the reason for the release of connection• Indicates the reason why connection could not established

Connection element identifier (CEID)• It consists of AAL type 2 path identifier and Channel identifier (CID). • AAL type 2 path identifier has field size of 4 octets. A value of ‘0’ in all octets

indicates “Null”.• Channel identifier has field size of 1 octet. It can have value in the range of 8 to

255. A value of ‘0’ indicates “Null”.

AAL type 2 service endpoint address (A2EA)• It carries end point address of the destination.• It can have E.164 or NSAP format.

Served User Generated Reference (SUGR)• It carries an unmodified reference provided by the originating ALSU to the

destination served user. Binding ID is used as this reference number


Explanation of parameters

Served User Transport (SUT)•It carries the served user data unmodified to the destination served user.

Test Connection Indicator (TCI)

•It indicates that the AAL type 2 connection to be established is a test connection SSCS information (SSCS)• It identifies the type and the capabilities of an AAL type 2 SSCS protocol.

- service specific information (audio)

- service specific information (multirate)

- service specific information (SAR)

Link Characteristics (LC)•It gives an indication of the resources required for the AAL type 2 connection and is used only for AAL type 2 path selection and connection admission control.


Implementation in M14/U4

•ANI – Adjacent AAL type 2 node identifier It identifies adjacent AAL type 2 node by unique name.

•AAL type 2 path identifier It identifies AAL type 2 path by unique number.

•AAL2 SEA – AAL type 2 Service Endpoint Address Address of AAL2 Service Endpoint in E.164 format.

•Ownership It indicates whether the AAL type 2 path is owned by AAL type 2 signalling entity or its peer.


Successful AAL type 2 connection establishment


Successful AAL type 2 connection release


Example of management operation


MML: Create Routing Objects for Iu Interface

•Create ATM Route in MGW towards RNC: Route = 11ZRRC:ROU=11,TYPE=AAL2:PRO=MTP3:NET=NA0,SPC=701,ANI=AAL2RNC1;

• Check that there is free VCLtp ZLCI: <interface id>,VC:<VPI>:FREE;

•Create an endpoint of VC level under Route 11. Path is 5, Interface Id is 2, VPI 1, VCI 33. Loss ratio 10 exp -3 , Mux delay 10 msZLJC:11,5:2,1,33:LOCAL:3,100;

•Unblock AAL2 path, waiting time for blocking commands is 18 secondsZLSU:AAL2RNC1:11:18;

• Interrogate AAL type 2 service endpoint addressZWEI:AAL2:SEA=35822;

ANI

Path ID(in Connection ID = VP/VC)

Owner

AAL2 E.164 address

AAL2 Slide

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