PDU
A protocol data unit is one SMPP command on the wire, such as submit_sm: a fixed header, then a body set by the command.
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A protocol data unit is one command on the wire in a named protocol: a fixed header, then a body that depends on the command. In SMPP the header carries the command length, command ID, command status and sequence number.
A submit_sm body carries the addresses, the data coding and the short_message field. That field carries the user data, and a UDH when esm_class signals one; the SMSC maps it into the 3GPP TS 23.040 TPDU on the radio side.
The SMPP decoder parses a pasted PDU in the browser, but it can only read the bytes it is given.
One PDU, field by field
- command_length
- 32
- command_id
- 0x00000004
- command_status
- 0x00000000
- sequence_number
- 1
- service_type
- source_addr_ton
- 0
- source_addr_npi
- 0
- source_addr
- dest_addr_ton
- 0
- dest_addr_npi
- 0
- destination_addr
- esm_class
- 0x00
Text description
Every PDU starts with a four-byte command length, command ID, command status and sequence number. The body follows.