Network Layers = source to destination
Transport Layers = program to program
Transport Layer
- Responsible for end-to-end delivery of messages
- Responsible for segmentation ( divide large data to small pieces ) and reassembly (make it be original data)
Internet transport-layer protocols
- Reliable (TCP) - Before it can send data it has to establish connection first
- congestion control - If high traffic reduce speed of sending data
- flow control - recieve data correctly by order
- connection setup - need to connect first
- no-frills extension of "best-effort" IP
- delay guarantees
- bandwidth guarantees (Shared by a lot of users)
- Responsible for addressing (Assign unique address) and routing (Major task and find the best part from source to destination ) of messages
Transport vs. Network layers
- Network layer = between host
- Transprot layer = between process
Transport Layer function
- Establish connection
- Connection Oriented
- Connectionless
- Quality of service
Linking to Application Layer
- Port number = use number to connect program to another program, 2 bytes is each source and destination
Packetization = Break a large message into a small pieces
Reassembly = Put them back together at the destination
Three ways handshake
1. Client host sends TCP SYN segment to server
2. Server host recieves SYN, replies with SYNACK segment
3. Client recieves SYNACK, replies with ACK segment
Closing connection
1. Client end system sends TCP FIN control segment to server
2. Server recieves FIN, replies with ACK
3. Client recieves FIN, replies with ACK
4. Connection closed
QoS - Try to guarantees something
- Timeliness - time to delivery of packets
- QoS routing ( realtime, choose parts that give the best bandwidth)
Socket programming - Allow to create network program without go deep in TCP
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