The document discusses the transport layer in computer networking. It explains that the transport layer provides logical communication between processes running on different hosts. It describes two main transport protocols: TCP and UDP. TCP provides connection-oriented transmission that is reliable and in-order, while UDP provides connectionless transmission that is unreliable and unordered. The document also covers topics like connection establishment, port numbers, sockets, and services provided by the transport layer.

1. Chapter 6

6. Transport Service Access Pint = Port No. Network Service Access Pint = IP No.

13. source port # dest port # 32 bits application data (variable length) sequence number acknowledgement number Receive window Urg data pnter checksum F S R P A U head len not used Options (variable length) URG: urgent data (generally not used) ACK: ACK # valid PSH: push data now (generally not used) RST, SYN, FIN: connection estab (setup, teardown commands) # bytes rcvr willing to accept Internet checksum (as in UDP) window scaling factor, Time-stamping, maximum segment length,… RFCs: 854, 1323 [4Bytes] seq # is byte-stream number of first data byte in segment

19. A state diagram for a simple connection management scheme. Transitions labeled in italics are caused by packet arrivals. The solid lines show the client's state sequence. The dashed lines show the server's state sequence.

29. Three protocol scenarios for establishing a connection using a three-way handshake. CR denotes CONNECTION REQUEST. (a) Normal operation, (b) Old CONNECTION REQUEST appearing out of nowhere. (c) Duplicate CONNECTION REQUEST and duplicate ACK.