1. 1 Transport Protocols Relates to Lab 5. An overview of the transport protocols of the TCP/IP protocol suite. Also, a short discussion of UDP.

2. 2 Orientation We move one layer up and look at the transport layer.

3. 3 Orientation Transport layer protocols are end-to-end protocols They are only implemented at the hosts

4. 4 Transport Protocols in the Internet UDP - User Datagram Protocol datagram oriented unreliable, connectionless simple unicast and multicast useful only for few applications, e.g., multimedia applications used a lot for services –network management (SNMP), routing (RIP), naming (DNS), etc. TCP - Transmission Control Protocol stream oriented reliable, connection-oriented complex only unicast used for most Internet applications: –web (http), email (smtp), file transfer (ftp), terminal (telnet), etc. The two major transport protocols of the Internet are

5. 5 UDP Format Port numbers identify sending and receiving applications (processes). Maximum port number is 2 16 -1= 65,535 Message Length is at least 8 bytes (I.e., Data field can be empty) and at most 65,535 Checksum is for header (of UDP and some of the IP header fields)

6. 6 Format of TCP segments TCP segments have a min. 20 byte header with ≥ 0 bytes of data.

7. 7 Port Numbers UDP (and TCP) use port numbers to identify applications A globally unique address for applications consists of 65,535 ports per protocol

8. 8 UDP - User Datagram Protocol UDP is supports unreliable transmissions of datagrams UDP merely extends the host-to-to-host delivery service of IP datagram to an application-to-application service The only thing that UDP adds to IP datagrams is multiplexing and demultiplexing (by adding port numbers)

9. 9 New Transport Protocols New Transport Protocols were added: –DCCP (2006): Datagram Congestion Control Protocol –SCTP (2000): Stream Control Transmission Protocol

10. 10 DCCP and SCTP SCTP “TCP for datagrams” connection-oriented (full duplex) more delivery options than TCP Message-oriented –preserves message boundaries Supports multiple flows (“streams” per connection) unreliable or reliable ordered or partially ordered congestion control support for multi-homing Used for signaling in telephone networks DCCP “UDP with congestion control” “TCP without reliable byte stream” connection-oriented message-oriented unreliable unordered congestion control Intended for applications that transfer large volumes of data Provide more service than UDP, but less than TCP

11. 11 SCTP Format Many different chunk types –Data chunks –Control chunks Each chunk has a type- dependent header

12. 12 DCCP Format