RDP: reliable data protocol

RDP is a connection-oriented transmission protocol designed to effectively transmit a large number of data for host monitoring applications such as download/upload and remote debugging. RDP attempts to provide only the necessary services to achieve effective operations and a small scale. Its main functions are as follows:

• RDP provides a full-duplex communication channel for each transport layer connection port;
• RDP attempts to send all user information reliably. Once the sending fails, an error is reported to the user. RDP extends the IP datagram service to ensure reliable transmission;
• RDP tries to detect and delete all corrupted and repeated data segments. It uses the verification code and serial number in the Data Segment header to implement this process;
• RDP allows you to send data segments at will. You must specify the sequence of data segments for sending when the connection is established;
• RDP will respond to data segments outside the validation sequence, which will release the resources of the sending end.

Compared with TCP, RDP supports simpler functions. RDP's Stream Control, buffer, and connection management modes are quite simple. The goal of RDP is to be simple and effective and suitable for a series of applications.

RDP function set may also be a subset to further reduce the size of Special execution. For example, a target processor requesting download from another host may execute an RDP module that only supports default open functions and single connections. This module may also choose not to perform unordered response confirmation.

Protocol Structure

The structure of the RDP version 2 protocol header is as follows:

1	2	3	4	5	6	8	16bit
SYN	ACK	Eak	RST	Nul	0	Ver No	Header Length
Sourceport
Destinationport
Data Length
Sequence Number
Acknowledgement number
Checksum
Variable header area...

Control flags-eight control bits are divided as follows: SYN: The SYN bit indicates the current synchronization segment. Ack: The ack bit indicates the acknowledged sequence number of the protocol header. Eack: The eack bit indicates that the field is currently recognized by the extension .. RST: The RST bit indicates that the data packet is a reset field. Nul: The NUL bit indicates that the data packet is an empty field. 0: the value of this field must be set to 0. Ver No: version number. The current version number is 2. Header Length-the length of the RDP protocol header. Source ports-source address to identify the communication process. In the network access protocol header, the combination of the source address and the destination address port identifier completely limits the connection and forms a connection identifier. This RDP can be used to differentiate multiple connections between two hosts. Destination Ports-the destination address to identify the target process in the communication. Data Length-the Data Length (eight bits) in this field. The data length does not include the RDP header. Sequence Number-the serial number of the field. Acknowledgement number-if the ACK bit is set in the protocol header, This is the serial number of the field, that is, the sender of the field is correctly received in the sequence. This field should be sent once the connection is successful. Checksum-check and ensure integrity. Variable header area-parameters used to transmit SYN and eack fields.

Protocols	UDP, rudp, IP, TCP, ICMP
Organization Source	RDP is defined by IETF (http://www.ietf.org) in RFC 908 and revised in RFC 1151.
Related Links	Http://www.javvin.com/protocol/rfc908.pdf:Reliable Data Protocol (RDP) Http://www.javvin.com/protocol/rfc1151.pdf:Version 2 of the reliable data Protocol (RDP)