MTP3B Slide

7/27/2019 MTP3B Slide

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Message Transfer Part level 3(MTPb)Switching Core Network Signalling

M14/U4





Nokia Siemens Networks Academy

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Document change history

Date Version Name Change comment

21.2.08 1 Gatot

Mardianto

More slides and NSN template





Protocol stacks – Narrowband / Broadband SS7





ATM Layer

ATM cell structure

ATM cell header structure





SAAL protocol structure


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ATM Adaptation Layer

Typical

Use

Fixed Connection

Video &

Audio

Data IP

Data SMDS

AAL AAL1 AAL2 AAL5 AAL3/4

Connection Oriented Connectionless

Synchronised Not Synchronised

Constant Variable Bit Rate

Source & Dest.

Connection

ATM Layer

Physical Layer

A B C D

ATM Service Classes

Convergence Sublayer

Segmentation and Reassembly Sublayer

AAL

CS

SAR

Higher Protocol Layers

ATM Layer




ATM Layer functionsUser data

AAL

Scramble frame andadapts the signals to theoptical or electricaltransmission medium

STM-1 Frame

PhysicalLayer

Convergence Sublayer (CS)

PayloadPayload Header Header

48 bytes5 bytes

Segmentationand Reassembly

Sublayer (SAR)

ATM Layer

Transmission Convergence(TC)

48 bytes

Physical Medium Dependent(PMD)

S D H

O / H

PayloadHeader




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 datawhich no timingrequest between

Tx and Rx




AAL5 PDU structure




SSCOP

SSCOP is a peer-to-peer protocol which provides the following

functions:

•Transfer of user data with sequence integrity

•Error correction by selective retransmission

•Flow control

•Keep Alive

•Connection control

•Protocol error detection and recovery

•Status reporting




SSCOP PDU names and definitions





Variable Name Description

VT(S)

N(S)

Send The sequence number of the next SD PDU to be transmitted for the firsttime. Incremented after transmission of a SD PDU. Does not increment

when the same SD PDU is retransmitted.

VT(PS)

N(PS)

Poll Send The current value of the POLL sequence number. Incremented beforetransmission of the next POLL PDU.

VT(A) Acknowledge The sequence number of the SD PDU that we expect to be acknowledgednext. Increments each time the SD PDU is acknowledged. Forms the

lower edge of the window of acceptable acknowledgements.

VT(PA) Poll Acknowledge

Sequence number of the STAT PDU (lowest edge of the acceptable STATsequence window) that we expect to receive next as an acknowledgement

to our POLL PDU. If the received STAT PDU contains and invalid valuethe recovery or release is initiated.

VT(MS) Maximumsend

Highest sequence number of a PDU that the transmitter interface cansend. (and the receiver will accept). Represents the upper edge of the

transmit window. Updated based on the receipt of a USTAT, STAT, BGN,BGAK, RS, RSAK, ER and ERAC PDU.

VT(PD) Poll data Represents the number of transmitted SD PDUs between 2 POLL PDUs.

Incremented upon transmission of an SD PDU and reset to zero upontransmission of a POLL PDU.

VT(CC) Connectioncontrol

Number of unacknowledged DGN, END, ER, or RS PDUs. If the ATMinterface sends END in response to a protocol error it does not wait for

the ENDAK and the value is not incremented.

VT(SQ)

N(SQ)

Transmitter connectionsequence

Identifies retransmitted BGN, ER and RS PDUs. Set to 0 when theSSCOP process starts and incremented and mapped to N(SQ) field

before transmission of either BGN, ER or RS PDU.

Transmitter State Variables





Variable Name Description

VR(R)

N(R)

Receive Expected sequence number of the next SD PDU.

VR(H) Highestexpected

The sequence number of the highest expected SD PDU. Updated uponreceiving of an SD or POLL PDU.

VR(MR)

N(MR)

Maximumreceive

The sequence number of the first SD PDU not allowed by the receiver. SDPDUs with N(S) higher than VR(MR) will be discarded.

VR(SQ) Receiver connectionsequence

Identifies retransmitted BGN, ER and RS PDUs. If the received N(SQ)field id different than VR(SQ) the PDU is processed as a new. If they are

equal the PDU is the retransmission.

Receiver state variables





SSCOP PDU formats





SSCOP PDU formats

Poll PDU

SD PDU





SSCOP PDU formats

STAT PDU

USTAT PDU





SSCOP Phases and timers

SSCOP connection is partitioned in different phases by timers

•Active Phase – When there are SD PDU to be transmittedor any acknowledgement outstanding. Timer for this phase is“poll”

•Transient Phase – When “poll” timer expires and no SD PDU

to be send and no acknowledgements outstanding. Timer for this phase is “keep_active”.

•Idle Phase – When STAT PDU is received during“keep_active” timer runtime. Timer for this phase is “idle”. After expiry of “idle” timer, transient phase is entered again.

•Connection Control Phase – During connectionestablishment, release, resynchronisation or recovery,transmission of PDU is protected by the “cc” timer.





SSCOP connection set up

examples

SSCOP flow control andcorrection procedure





Functions of SSCF

•SSCF maps the data coming from the MTP3 into SSCOP PDU

for transfer. No additional protocol specific information is addedto the MTP3 data.

•SSCF receives signals from SSCOP and MTP3 and maintainslocal state variables pertaining to the status of the link. SSCF

also reports to the layer management about changes insignalling link state.

•Same function as LSSU (Link Status Signal Unit) in MTP2





SSCF PDU format





Frame format of MTP3b over SAAL





F CK SIF SIO LIF

I

BFSN

B

I

BBSN F

First bit

transmitted8 16 8n, n>2 8 2 6 1 7 1

7 8

User Data

SIO

SIO

SIODPCOPCS

L

C

User Data DPCOPCS

L

S

User Data DPCOPCS

L

SCIC

SIOUser Data DPCOPCCICTUP

ISUP

Network Management

SCCP

Structure of messages from MTP users





SLS OPC DPC

OPC Originating Point Code

DPC Destination Point Code

SLS Signalling Link Selection

User information

subfieldLabel

DCBA

Subservice

field (SSF)

DCBA

Service

indicator(SI)

Signalling Information Field (SIF)

Service information

octet (SIO)First bit

transmitted

4 bits 14 bits 14 bits 4bits 4 bits

Routing label

0000-0011 : IN0

0100-0111 : IN11000-1011 : NA0

1100-1111 : NA1

0000 : SNM

0001 : SNT0011 : SCCP

0100 : TUP

0101 : ISUP

1001 : B-ISUP

1010 : Satellite B-ISUP

Structure of SIF, SIO and Routing Label





Signalling Link Selection (SLS)

To control in LOAD Sharing the selection of a Signalling Link in

a Signalling Route Set, giving the corresponding SLC.





1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

- - - - - - - - - -- -- -- -- -- -- --

0000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0001 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

0010 1 1 3 3 3 3 3 3 3 3 3 3 3 3 3 3

0011 1 2 1 4 4 4 4 4 4 4 4 4 4 4 4 4

0100 1 1 2 1 5 5 5 5 5 5 5 5 5 5 5 5

0101 1 2 3 2 1 6 6 6 6 6 6 6 6 6 6 6

0110 1 1 1 3 2 1 7 7 7 7 7 7 7 7 7 7

0111 1 2 2 4 3 2 1 8 8 8 8 8 8 8 8 8

1000 1 1 3 1 4 3 2 1 9 9 9 9 9 9 9 9

1001 1 2 1 2 5 4 3 2 1 10 10 10 10 10 10 10

1010 1 1 2 3 1 5 4 3 2 1 11 11 11 11 11 11

1011 1 2 3 4 2 6 5 4 3 2 1 12 12 12 12 12

1100 1 1 1 1 3 1 6 5 4 3 2 1 13 13 13 13

1101 1 2 2 2 4 2 7 6 5 4 3 2 1 14 14 14

1110 1 1 3 3 5 3 1 7 6 5 4 3 2 1 15 15

1111 1 2 1 4 1 4 2 8 7 6 5 4 3 2 1 16

Load Sharing Between Links

LINK

SLS





1 2 3 4 5 6 7 8

- - - - - - - -

0000 1 1 1 1 1 1 1 1

0001 1 1 1 1 1 1 1 1

0010 1 1 1 1 1 1 1 2

0011 1 1 1 1 1 2 2 2

0100 1 1 1 2 2 2 2 3

0101 1 1 1 2 2 2 2 3

0110 1 1 2 2 2 3 3 4

0111 1 1 2 2 3 3 3 4

1000 1 2 2 3 3 3 4 5

1001 1 2 2 3 3 4 4 5

1010 1 2 2 3 4 4 5 6

1011 1 2 3 3 4 4 5 6

1100 1 2 3 4 4 5 6 7

1101 1 2 3 4 5 5 6 7

1110 1 2 3 4 5 6 7 8

1111 1 2 3 4 5 6 7 8

Load Sharing Between Link

Sets

LINK SET

SLS





CCS7 MTP-3

Level 3 - Signalling Network Level

–This level has two functions:▪ Message handling - routing of outgoing messages,

distribution of incoming messages (matches OSI layer 3)

▪ Network management - (functions go beyond OSI layer

3.)Sends Signalling Network Test (SNT) and Signalling

Network Management (SNM) messages.

–Uses Signalling Point Code (SPC) to

address messages to individual networkelements.

–Uses Service Information Octet (SIO) toaddress messages to higher level

applications





Signalling Network Management

It is an MTP-3b function taking care of

signalling network management duringfaulty situations.

• Loss of signalling link.

• Loss of signalling point.

• Congestion.





Signaling Network Management

The SIO in MSU classifies two groups (See in MML>> ZNPI):

SNM (Signalling Network Management) , SI in SIO=0000

SNT (Signalling Network Testing & Maintenance) , SI in

SIO=0001





SNT Messages

There are only two SNT messages:

SLTM (Signalling Link Test Message)

SLTA (Signalling Link Test Acknowledge)





Structure of the NetworkManagement messages - SNM

H1 H0 SLC OPC DPC

4bits 4 bits 4 bits 14 bits 14 bits 4 bits

OPC = Originating point code,

DPC = Destination point code,

SLC = Signalling link code,H0 = Heading code indicating which message group the message belongs to.

H1 = Heading code indicating the message within the group in question.

Subservicefield 0000

First bit

transmitted

F CK SIF SIO LIF

I

BFSN

B

I

BBSN FMTP message

User informationsubfield





Heading Codes for Groups and Messages

GROUP H0\H1 0001 0010 0011 0100 0101 0110 0111 1000

0000

CHM 0001 COO COA CBD CBA

ECM 0010 ECO ECA

FCM 0011 TFC TFC

TFM 0100 TFP TFA

RSM 0101 RST

MIM 0110 LIN LUN LIA LUA LID LFU LLT LRT

TRM 0111 TRA1000





Network Control Function

Signaling Traffic Management

Changeover, ChangebackForced rerouting

Controlled Rerouting

Signaling Link Management

Link activation deactivationLink restoration

Link Set activation

Signaling Route Management

Transfer prohibited, allowedTransfer controlled, restricted

Route set test

SIGNALING NETWORK MANAGEMENT

C





Changeover to a parallel link

A B

SLC=x SLC=y

1) On link y, XCO (SLC=x), N(S) of last correctly received PDU

2) XCA (N(S) of last correctly received PDU)

3) Change Signalling link selection table in CCSU

Ch b k d li k





Changeback to a recovered link

A B

SLC=x SLC=y

1) Traffic to Signalling link with SLC=x

2) Update Signalling link selection table in all CCSUs

3) CBD

4) CBA

T f hibit d (l f d ti ti )





Transfer-prohibited (loss of a destination)

2) TFP (DPC=D)

2) TFP (DPC=D) 2) TFP (DPC=B)

1)

SP A

SP B

SP C

SP E

SP D

T f ll d ( t il bl )





Transfer-allowed (route available)

2) TFA (DPC=D)

2) TFA (DPC=D)2) TFA (DPC=B)

1)

SP A

SP B

SP C

SP E

SP D

MTP3b MML P t H dli



For public use IPR applies

MTP3b MML Parameter Handling

•Mostly valid both for MTP and MTPb, to change parameters

•Level 3 parameters: NMI (interrogate) and NMM (modify)•Network-Specific Parameters: NMO (interrogate) and NMC(modify)

•Signalling Link-Specific Parameters: NOI (interrogate), NOM(modify)

– Parameter G is for ATM specific parameters (SAAL level)

– The second parameter defines which parameter from parameter set tomodify

– E.g., Interrogate the data on all the parameter groups inparameter sets 1, 3, and 8-10, and display the parameter

descriptions. – ZNOI:1&3&8&&10,,Y;

• Signalling Route Set-Specific Parameters: NNI (interrogate),NNM (modify)

http://127.0.0.1:43231/NED/NED?action=retrieve&library=m14_0_2008_01_11&identifier=mmlnoi&edition=0&language=en&coverage=global&encoding=xhtml_1_0&component=data&item=data&pointer=cmdnoi




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