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MMS related Protocol structure & frame format

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Get from http://wiki.wireshark.org/IsoProtocolFamily

 

 

 

 

 

Summary

 

 

Packet-based vs. stream-based:

 

COTP transports packets of data from one user to the other, so the receiver will get exactly the same data boundaries as the sender transmitted.

 

TCP transports a continuous stream of data to the receiver, so the protocol on top of TCP often has to add such boundaries itself (see the TPKT protocol for such a protocol).

 

TSAPs vs. ports:

 

To multiplex several conversations between two hosts, COTP uses TSAP's which are variable length binary blobs (often a meaningful string is used).

 

These TSAP's are matched at connection establishing phase, and replaced by the 2 byte (destination/source) references at data transfer.

 

TCP uses ports for this. One notable difference is that TSAP's are singletons - if a TSAP is used for a connection it cannot be used by another. XXX - Needs clarification. A single TSAP (Transport Service Access Point) may be used by multiple connections.

 

Tranport Layer:

 

Protocol                     Note

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

COTP                          

TPKT                           = TPKT works on TCP port 102 to emulate COTP

TCP

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

 

 

1.  TPKT = RFC 1006

 

It start with \x03\X00.

 

TPKT is used to "emulate" ISO transport services COTP on top of TCP. The two major points missing in TCP (compared to COTP) are the TSAP addressing and the detection of packet boundaries on the receiving host.


Include Packet Header and TPDU, The format of the TPDU is defined in [ISO8073].  

Note that only TPDUs formatted for transport class 0 [TP0] are exchanged (different transport classes may use slightly different formats).

 

 

 

 

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      vrsn     |    reserved   |          packet length        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 

 

Header:version = always 3, 1 byte

 

TPDU = max. 65531. Based on the size of the data transfer (DT) TPDU, this permits a maximum TSDU size of 65524 octets.

 

 

2.  COTP = ISO 8073 / RFC983

 

Connection-oriented transport protocol

 

To support expedited data, a non-standard TPDU, for expedited data is permitted.  The format used for the ED TPDU is nearly identical to the format for the normal data, DT, TPDU.  The only difference is that the value used for the TPDU's code is ED, not DT:

 

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | header length | code  |credit |TPDU-NR and EOT|   user data   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |      ...      |      ...      |      ...      |
      |      ...      |      ...      |      ...      |      ...      |
      |      ...      |      ...      |      ...      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 

 

 

 

 

TPDU Code

-------------------
CR = 0xE0, Connection Request

CC = 0xD0, Connection Confirm
DR = 0x80, Disconnection Request
DT = 0xF0, Data Transfer
ED = 0x70, Expected Data transfer

 

After the credit field (which is always ZERO on output and ignored on input), there is one additional field prior to the user data.

     

TPDU-NR and EOT = 8 bits

 Bit 7 (the high-order bit, bit mask 1000 0000) indicates the end of a TSDU.  All other bits should be ZERO on output and ignored on input.

 

  

The format of a CR or CC TPDU is:

       0                   1                   2                   3  
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | header length | code  | credit|     destination reference     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       source reference        | class |options| variable data |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    ...        |      ...      |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      |    ...        |   user data   |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 

 

 

 

The format of a DR TPDU is:

       0                   1                   2                   3  
       0 1  2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | header length | code  | credit|     destination reference     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       source reference        |     reason    | variable data |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    ...        |      ...      |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      |      ...      |   user data   |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 

The format of a DT or ED TPDU is:

       0                   1                   2                   3  
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+
      | header length | code  | credit|         TPDU-NR and EOT       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   user data   |      ...      |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      |    ...        |      ...      |      ...      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 


 

3.  ISO 8327-1

ISO Session Protocol

 

 

 

 

 

Format

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

SPDU Type  --  1 byte

Length  --  1 byte

Connect Accept Item  --  8 bytes

Session Requirement  --  4 bytes

Calling Session Selector  --  4 bytes

Called Session Selector  --  4 bytes

Session User Data  --  ...

 

 

ISO Session Protocol (ISO-SP) Messages:

Functional unit

SPDU code

SPDU name

Kernel

CN
OA
CDO
AC
RF
FN
DN
AB
AA
DT
PR

CONNECT
OVERFLOW ACCEPT
CONNECT DATA OVERFLOW
ACCEPT
REFUSE
FINISH
DISCONNECT
ABORT
ABORT ACCEPT
DATA TRANSFER
PREPARE

Negotiated release

NF
GT
PT

NOT FINISHED
GIVE TOKENS
PLEASE TOKENS

Half-duplex

GT
PT

GIVE TOKENS
PLEASE TOKENS

Duplex

 

No additional associated SPDUs

Expedited data

EX

EXPEDITED DATA

Typed data

TD

TYPED DATA

Capability data exchange

CD
CDA

CAPABILITY DATA
CAPABILITY DATA ACK

Minor synchronize

MIP
MIA
GT
PT

MINOR SYNC POINT
MINOR SYNC ACK
GIVE TOKENS
PLEASE TOKENS

Symmetric synchronize

MIP
MIA

MINOR SYNC POINT
MINOR SYNC ACK

Data separation

 

No additional associated SPDUs

Major synchronize

MAP
MAA
PR
GT
PT

MAJOR SYNC POINT
MAJOR SYNC ACK
PREPARE
GIVE TOKENS
PLEASE TOKENS

Resynchronize

RS
RA
PR

RESYNCHRONIZE
RESYNCHRONIZE ACK
PREPARE

Exceptions

ER
ED

EXCEPTION REPORT
EXCEPTION DATA

Activity management

AS
AR
AI
AIA
AD
ADA
AE
AEA
PR
GT
PT
GTC
GTA

ACTIVITY START
ACTIVITY RESUME
ACTIVITY INTERRUPT
ACTIVITY INTERRUPT ACK
ACTIVITY DISCARD
ACTIVITY DISCARD ACK
ACTIVITY END
ACTIVITY END ACK
PREPARE
GIVE TOKENS
PLEASE TOKENS
GIVE TOKENS CONFIRM
GIVE TOKENS ACK

 

  


 

4.  ISO 8823

ISO Presentation Protocol, on top of ASN.1, BER.


 

Frame format

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

Mode-selector  --  3 bytes

Normal-mode-parameters

Padding  --  1 byte

Protocol-version  --  1 byte, 80 = version-1

calling-presentation-selector  --  4 bytes

called-presentation-selector  --  4 bytes

presentation-contex-definition-list  --  ??

Padding --  1 byte

Presentation- requirement  --  1 byte

User-data  --  ...

 

 

Protocol Structure - ISO-PP: OSI Presentation Layer Protocol (X.226, X.216, ISO 8823, 8822)

 

Connection Release Primitive

Token Handling Primitive

P-RELEASE request

P-RELEASE indication

P-RELEASE response

P-RELEASE confirm

P-TOKEN-GIVE request

P-TOKEN-GIVE indication

P-TOKEN-PLEASE request

P-TOKEN-PLEASE indication

P-CONTROL-GIVE request

P-CONTROL-GIVE indication


Presentation Exception Reporting Primitive

Activity Management Primitive

P-P-EXCEPTION-REPORT indication

P-U-EXCEPTION-REPORT request

P-U-EXCEPTION-REPORT indication

P-ACTIVITY-START request

P-ACTIVITY-START indication

P-ACTIVITY-RESUME request

P-ACTIVITY-RESUME indication

P-ACTIVITY-INTERRUPT request

P-ACTIVITY-INTERRUPT indication

P-ACTIVITY-NTERRUPT response

P-ACTIVITY-INTERRUPT confirm

P-ACTIVITY-DISCARD request

P-ACTIVITY-DISCARD indication

P-ACTIVITY-DISCARD response

P-ACTIVITY-DISCARD confirm

P-ACTIVITY-END request

P-ACTIVITY-END indication

P-ACTIVITY-END response

P-ACTIVITY-END confirm

Synchronization Services Primitive

P-SYNC-MINOR request

P-SYNC-MINOR indication

P-SYNC-MINOR response

P-SYNC-MINOR confirm

P-SYNC-MAJOR request

P-SYNC-MAJOR indication

P-SYNC-MAJOR response

P-SYNC-MAJOR confirm


 

 

5.  ISO 8650-1, ACSE-1

ISO Association Control Service Element (Layer 7)

 

The OSI method for establishing a call between two application programs. ACSE checks the identities and contexts of the application entities, and could apply an authentication security check.

 

ICCP uses the ISO Association Control Service element (ACSE) to establish logical associations. Multiple associations may be established from a client to multiple, different control center servers.

 

Application Association & network connection are different.

 

 

 

6.  MMS

ISO 9506-2

 

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