Networking Notes 3 - Internet Transport-Layer Protocol

More than one transport-later protocol available to applications

Internet: TCP and UDP

TCP

• Reliable, in-order delivery
• Connection setup
• Flow control
• Congestion control

UDP

• Unreliable, unordered delivery

More about TCP

Full name: Transmission Control Protocol

• Connection-oriented protocol
• Provide a reliable unicast end-to-end byte stream over an unreliable internetwork

Before any data transfer, TCP establishes a connection(hand shark?)

1. Client: send Request a connection
2. Server: Accept a connection
3. Do Data Transfer
4. Client: Disconnect

Reliable

• The reason why we use TCP is because it is reliable.
• Byte stream is broken up into chunks - segments
• The receiver sends acknowledgements (ACKs) for segments.
• TCP maintains a timer, if ACK is not received in time, the segment is retransmitted.
• Detecting errors (checksums for header and data)
• Each byte has a sequence number

UDP

Full name : User Datagram Protocol

• Connectionless - no handshark
• Unreliable
• No flow control
• No congestion control

Good:

• No connect establishment ← can add delay
• simple
• small segment header
• no congestion control: as fast as desired

Good for: Streaming multimedia application

• Loss tolerant
• rate sensitive
• DNS