3.3.1 Data Interchange Method:
In data communication, the data transfer between nodes in a communication subnet is called
Its pseudo-technology is called data exchange technology.
1, Circuit Exchange: From the telephone switching network technology
2. Storage and Forwarding Exchange: from Telegram transmission mode
3, Packet Exchange: Also known as packet switching two kinds
Services provided by the 3.3.2 Network layer
1. Connection-oriented services
2, for non-connected services
3.3.3 Route Selection
3.3.4 Congestion Control
The most typical protocol for the network layer is the IP protocol, x., when scrolling trunking, and ATM
The transport layer is between the communication subnet and the resource subnet, which plays a connecting role
3.4.1 function of the transport layer
The transport layer is the core of OSI/RM, which provides services similar to the data connection layer
The difference is the data Link layer control in the local area network, "one-to-one link on the ' point '" transmission situation,
and "End-to-end" refers to the source end to the destination, in the middle can have one or more switching nodes
Output Layer function
1, end-to-end delivery
2. Addressing
3. Reliable Transmission
4. Flow control
5. Re-use
6. Segmentation and Reorganization
3.4.2 connection oriented and no connection oriented
Connection-oriented protocol establishes a virtual circuit or path between the source and destination of the Internet
Then many packets belonging to the same message are passed on this path. Connection-oriented connections are established,
Data transfer and connectivity in up to three stages
The non-connected transport service provides only one type of service for the upper layer, which provides a single, separate unit of data for all transmission information
Each unit contains all protocol control information required for transmission, but does not provide sequence and flow control
TCP and UDP in the TCP/TP protocol are transport layer protocols
The TCP protocol for Transmission Control Protocol is a connection-oriented protocol, and the user Data protocol UDP is a non-connection oriented protocol.
Network layer and Transport layer