网络术语segment packet datagram frame stream

TCP/UDP segment

IP datagram/packet (where packet can be commonly refered to any layer)

(date link )Frame

 

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Defined from From RFC 1122

Segment

A segment is the unit of end-to-end transmission in the TCP protocol. A segment consists of a TCP header followed by application data. A segment is transmitted by encapsulation inside an IP datagram.

Message

In this description of the lower-layer protocols, a message is the unit of transmission in a transport layer protocol. In particular, a TCP segment is a message. A message consists of a transport protocol header followed by application protocol data. To be transmitted end-to- end through the Internet, a message must be encapsulated inside a datagram.

IP Datagram

An IP datagram is the unit of end-to-end transmission in the IP protocol. An IP datagram consists of an IP header followed by transport layer data, i.e., of an IP header followed by a message.

In the description of the internet layer (Section 3), the unqualified term "datagram" should be understood to refer to an IP datagram.

Packet

A packet is the unit of data passed across the interface between the internet layer and the link layer. It includes an IP header and data. A packet may be a complete IP datagram or a fragment of an IP datagram.

Frame

A frame is the unit of transmission in a link layer protocol, and consists of a link-layer header followed by a packet.