Transport Layer
Role of the Transport Layer
-Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
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Tracking the individual communication between applications on the source and destination hosts
Segmenting data for manageability and reassembling segmented data into streams of application data at the destination
Identifying the proper application for each communication stream
Conversation Multiplexing
Segmenting the data
Enables many different communications, from many different users, to be interleaved (multiplexed) on the same network, at the same time.
Provides the means to both send and receive data when running multiple applications.
Header added to each segment to identify it.
Introducing UDP
User Datagram Protocol (UDP
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RFC 768
Connectionless
Unreliable delivery
No ordered data reconstruction
No flow control
Stateless protocol
Applications that use UDP:
Domain Name System (DNS)
Video Streaming
Voice over IP (VoIP)
Separating Multiple Communications
Port Numbers are used by TCP and UDP to differentiate between applications.
TCP and UDP Port Addressing
Used to examine TCP connections that are open and running on a networked host
Communication TCP Connection, Establishment and Termination
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Establishes that the destination device is present on the network.
Verifies that the destination device has an active service and is accepting requests on the destination port number that the initiating client intends to use for the session.
Informs the destination device that the source client intends to establish a communication session on that port number
TCP Reliability – Ordered Delivery
Sequence numbers used to reassemble segments into original order
TCP Reliability – Acknowledgement and Window Size
TCP Flow Control – Congestion Avoidance
Datagram Reassembly