Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 4: Transport And Application Layer - Coggle Diagram
Chapter 4:
Transport And Application Layer
4.1.1 Explain the purpose of the transport layer in managing the transportation of data in end-to-end communication.
4. Transport Layer Reliability
TCP/IP provides two transport layer protocols:
Transmission Control Protocol (TCP)
:check: Considered reliable which ensures that all of the data arrives at the destination
:check:Additional fields needed in header which increases size and delay
User Datagram Protocol (UDP)
:check:Does not provide for reliability
:check:Fewer fields and is faster than TCP
5. TCP (Cont.)
TCP transport is similar to sending tracked packages. If a shipping order is broken up into several packages, a customer can check online to see the order of the delivery
TCP Three Responsibilities:
:check:Numbering and tracking data segments
:check:Acknowledging recieved data
:check:Retransmitting any unacknowledged data after a certain period of time
3. Conversation Multiplexing
Segmenting the data into smaller chunks enables many different communications to be multiplexed on the same network
6. Benifits UDP
:check:Use UDP for less overhead and toreduce possible delays.
:check:Best-effort delivery (unreliable)
:check:No acknowledgment
:check:Similar to a non-register letter
2. Transport Layer Responsibilities
Tracking the conversation
- Tracks each individual conversation flowing between a source and a destination application.
Segmentation
- Divides the data into segments that are easier to manage and transport. Header used for reassembly is used for tracking
Identifying the Application
- Ensure that even with multiple applications running on a device, all applications receive the correct data via port numbers
1. Role of the Transport Layer
Responsible for eatablishing a temporary communication session between two applications and delivering data between them
Link between the appliaction layer and the lower layers that are responsible for network transmission
7. The Right Transport Layer Protocol for the Right Application
:<3: TCP - databases, web browsers, and email clients require that all data that is sent arrives at the destination in its original condition.
:<3: UDP - if one or two segments of a live video stream fail to arrive, if disruption in the stream, may not be noticeable to the user
4.1.3 Determine whether high-reliability TCP transmission, or non-guaranteed UDP transmission, are the best suited for common applications
TCP flow control-congestion avoidance
Retransmission of segments can make the congestion worse
To avoid and control congestion, TCP employs several congestion handling mechanisms, timers and algorithms
Congestion causes retransmission of lost TCP segments
Example: Reduce the number of bytes it sends before receiving an acknowledgment
UDP low overhead versus reliability
No retransmission, sequencing and flow control
Functions not provided by the transport layer implemented elsewhere
UDP not connection-oriented
TCP flow control-window size and acknowledgments
Window size agreed on during 3-way handshake
Typically, PC B will not wait for 10 000bytes before sending an acknowledgment
In the figure, the source is transmitting 1460 bytes of data within each segment
PC A can adjust its send window as it receives acknowledgments from PC B
Applications that uses the TCP - The TCP frees the applications from having to manage reliability.
Examples of the Applications that uses the TCP
HTTP
Telnet
FTP
SMTP
TCP reliability-ordered delivery
During session setup, an initial sequence number (ISN) is set - represents the starting value of the bytes
As data is transmitted during the session, the sequence number is incremented by the number of bytes that have been transmitted
Represents the first data byte of the TCP segment
Missing segments can then be identified
Sequence numbers are assigned in the header of each packet
TCP three-way handshake analysis
The three-way handshake
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
Informs the destination device that the source client intends to establish a communication session on that port number
Establishes that the destination device is present on the network
TCP session termination
To end each one-way TCP session, a two-way handshake, consisting of a FIN segment and an Acknowledgement (ACK) segment, is used.
To terminate a single conversation supported by TCP, four exchanges are needed to end both sessions.
To close a connection, the finish (FIN) control flag must be set in the segment header
Applications that uses the UDP - There are three types of applications which are best suited for the UDP which is live videos and the multimeadia, simple requests and replies and handling the reliability by themselves.
Examples of the Applications that uses the UDP
DHCP
DNS
SNMP
IPTV
VoIP
TFTP
4.1.2 Explain the characteristics of the TCP and UDP protocols, including port numbers and their uses
5. Multiple Separate Communications
:<3: Users expect to simultaneously receive and send email, view websites and make a VoIP phone call.
:<3: TCP and UDP manage multiple conversations by using unique identifiers called port numbers
4. UDP Header
:<3: UDP is a stateless protocol – no tracking
:<3: Reliability handled by application
3. UDP Features
:<3: Features of UDP
Data is reconstructed in the order that it is received
Any segments lost are not resent
No session establishment
Does not inform the sender about resource availability
2. TCP Header
:<3: Source and Destination Port used to identify application
:<3: Sequence number used for data reassembly
:<3: number indicates data has been received and ready for next byte from source
:<3: Header length – length of TCP segment header
:<3: Control bits – purpose and function of TCP segment
:<3: Window size – number of bytes that can be accepted at one time
:<3: Checksum – Used for error checking of segment header and data
1. TCP Features
:<3: Establishing a Session
Connection-oriented protocol
Ensures the application is ready to receive the data
Negotiate the amount of traffic that can be forwarded at a given time
:<3: Reliable Delivery
Ensuring that each segment that the source sends arrives at the destination
:<3: Same-Order Delivery
Numbering & Sequencing the segments guarantees reassembly into the proper order
:<3: Flow Control
Regulate the amount of data the source transmits
Guide (Colour Code)
Firdaus
Amirul fahim
Dayangku UmiAfifah
Mas Hafiszie
Flaveen
