max size in the sua

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Hi, 

 

T-REC-Q.714 says that max data size is 3952 octets. Is this limit of max
data size also valid in case of SUA. 

Please find attached portion of the T-REC-Q.714.

 

Thanks 

Rishi Srivastava

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restriction on the max size.txt (text/plain, 2.6 KB)
1.1.2 Protocol classes

 

When one connectionless message is not sufficient to convey the user data contained in one NSDU

making use of MTP services provided by an MTP-SAP that supports a maximum MTP SDU size

of 272 octets including the MTP routing label, a segmenting/reassembly function for protocol classes

0 and 1 is provided. In this case, the SCCP at the originating node or in a relay node provides

segmentation of the information into multiple segments prior to transfer in the "data" field of XUDT

(or as a network option LUDT) messages. At the destination node, the NSDU is reassembled.

If it is certain that only MTP services according to ITU-T Q.2210 are used in the network, then no

segmentation information is needed.

 

The connection-oriented protocol classes (protocol classes 2 and 3) provide the means to set up

signalling connections in order to exchange a number of related NSDUs. The connection-oriented

protocol classes also provide a segmenting and reassembling capability. If an NSDU is longer than

255 octets, it is split into multiple segments at the originating node, prior to transfer in the "data"

field of DT messages. Each segment is less than or equal to 255 octets. At the destination node, the

NSDU is reassembled.

 

4.1.1 Segmentation/reassembly

4.1.1.1 Segmentation

4.1.1.1.1 General

The connectionless segmentation mechanism is provided by the SCLC block. It is used in two

situations:

1) When an SCCP user generates an N-UNITDATA request primitive and SCLC is able to

segment the message before passing it to SCRC.

2) When the compatibility test in SCRC sends a message to SCLC for segmentation.

The actions of SCLC depends on the length of the user data as follows:

– If the length of the user data is lower than Z octets6, then SCLC shall avoid segmentation

and an XUDT or LUDT or UDT message is passed to SCRC.

– If the length of the user data is between Z (lower limit) and Y (upper limit, see

Table 19/Q.713) octets, then the SCCP may decide to segment the message, based on locally

stored information regarding network performance and configuration.

– If the length of the user data is between Y octets and 3952 octets inclusive, then the SCCP

shall segment the message. If segmentation is not possible, then the error treatment is

initiated.

– If the length of the user data is greater than 3952 octets then the error treatment shall apply.

 

Bits 4-1 of octet 1 are used to indicate the number of remaining segments. The values 0000 to 1111

are possible; the value 0000 indicates the last segment.
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