Transport Protocols
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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.
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Transport Protocols. Relates to Lab 5. An overview of the transport protocols of the TCP/IP protocol suite. Also, a short discussion of UDP. Orientation. We move one layer up and look at the transport layer. Orientation. Transport layer protocols are end-to-end protocols - PowerPoint PPT Presentation
Transcript of Transport Protocols
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
Orientation
• We move one layer up and look at the transport layer.
ApplicationLayer
NetworkLayer
Link Layer
IP
ARPHardwareInterface
RARP
Media
ICMP IGMP
TransportLayer
TCP UDP
UserProcess
UserProcess
UserProcess
UserProcess
3
Orientation
• Transport layer protocols are end-to-end protocols • They are only implemented at the hosts
Application
Transport
Network
HOST
Data Link Data Link Data Link
Network
Application
Transport
Network
HOST
Data Link
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Transport Protocols in the Internet
UDP - User Datagram ProtocolUDP - 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 Internet supports 2 transport protocols
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UDP - User Datagram Protocol
• UDP 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 is multiplexing and demultiplexing
UDP
IP IPIP IP IP
UDP
Applications Applications
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UDP Format
IP header UDP header UDP data
UDP message length Checksum
DATA
20 bytes 8 bytes
0 15 16 31
Source Port Number Destination Port Number
• Port numbers identify sending and receiving applications (processes). Maximum port number is 216-1= 65,535
• Message Length is at least 8 bytes (I.e., Data field can be empty) and at most 65,535
• Checksum is for whole UDP segment and pseudo header of IP - I.e., some of the IP header fields -protocol number, source and dest. address and UDP length field (again).
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Port Numbers
• UDP (and TCP) use port numbers to identify applications• A globally unique address at the transport layer (for both UDP
and TCP) is a tuple <IP address, port number>• There are 65,535 UDP ports per host.
IP
TCP UDP
UserProcess
Demultiplex
based on
Protocol field in IP
header
UserProcess
UserProcess
UserProcess
UserProcess
UserProcess
Demultiplex
based on
port number
