4. Transport Layer Flashcards
What is the transport layer responsible for?
- Logical communications between applications running on different hosts
What layers are responsible for network transmission?
- Link between the application layer and the lower layers
What information does Transport Layer adds? ( Responsibilities )
- Header Information
What does Transport Layer track? ( Responsibilities )
- Individual conversations
What does transport layer segment and reassembling ? ( 2 , Responsibilities )
- Data ( Segmenting )
- Segments ( Reassembling )
- Uses segmentation and multiplexing to enable different communication conversations to be interleaved on the same network
What will transport layer do on multiple conversations? ( 3 , Responsibilities )
- Identify
- Separate
- Manage
What does transport layer protocols specify? ( 2 )
- How to transfer between hosts
- Responsible for managing reliability requirements of a conversation
- IP does not specify how the delivery or transportation of the packets takes place
Transport Layer includes what protocols? ( 2 )
- TCP Protocols
- Provides reliability and flow control
- UDP Protocols
- Provides basic functions for delivering datagrams between the appropriate applications, with very little overhead and data checking
List out TCP basic operations ( 5 )
- Number and track data segments transmitted to a specific host from a specific application
- Acknowledge received data
- Retransmit any unacknowledged data after a certain amount of time
- Sequence data that might arrive in wrong order
- Send data at an efficient rate that is acceptable by the receiver
- Transmission Control Protocol ( TCP )
What is the required protocol properties for UDP and TCP?
TCP
1. Reliable
2. Acknowledges Data
3. Resends Lost Data
4. Delivers Data in Sequencial Order
UDP
1. Fast
2. Low Overhead
3. Does not Require Acknowledgements
4. Does not Resend Lost Data
5. Delievers Data as it Arrives
What is UDP is known for?
- Best-effort delivery protocol because there is no acknowledgement that that data is received at the destination
- It was an unreliable protocol because it has little overhead and data checking
- User Datagram Protocol ( UDP )
- It is also a connectionless protocol
What applications uses UDP?
- Request-and-Reply applications
- Where data is minimal, and retransmission can be done quickly
When will TCP used?
- If it is important that all the data arrives and that it can be processed in its proper sequence, TCP is used as the transport protocol
What are the features for TCP? ( 4 )
- Establishes a Session
- Ensures Reliable Delievery
- Provides Same-Order Delivery
- May provide multiple routes
- Supports Flow Control
- It is a stateful protocol which means it keeps track of the state of the communication session
What will TCP records? ( 2 )
- Which information it has sent
- Which information has been acknoledged
What is the 2 most important things in TCP and UDP header?
- Source Port
- Destination Port
What does TCP handles?
- All tasks associated with driving the data stream into segments, providing reliability, controlling data flow, and reording segments
What is the features for UDP? ( 4 )
- Data is reconstructed in the order that it is received
- Any segments that are lost are not resent
- There is no session establishment
- The sending is not informed about resource availability
What application uses UDP? ( 3 )
- Live video and multimedia applications
- Simple request and reply applications
- Applications that handle reliability themselves
What does TCP and UDP transport layer protocols uses to manage multiple, simultaneous conversations?
- Port Numbers
What are placed within the segment?
- Source Port Number
- Destination Port Number
- They are then encapsulated within an IP packet
What is the name for the source IP address and source port number, or the destination IP address and destination port number?
- Socket
What does sockets enable?
- Enable multiple process, running on a client, to distinguish themselves from each other, and multiple connections to a server process to be distinguished from each other
What is the number range for well-known ports?
- 0 - 1023
- Reserved for common or popular services ( web-browser, remote access clients )