Transport layer Flashcards
TCP Features
- Establish session - establish connection between source and destination device
- Ensure reliable delivery - ensures all packets arrive at destination
- Ensure same order delivery - sequencing
- Flow control - limit rate of data flow
UDP Features
- No flow control
- No session establishment
- Segments are ordered in the way they were received
- Segments that are lost are not sent back
TCP Protocols
- HTTP
- SMTP
- FTP
UDP Protocols
- Live and multimedia applications
- Simple request and reply applications - DNS DHCP
- Applications that handle reliability themselves - TFTP
Socket pair
Combination of destination IP address and destination Port address or source IP address and destination port address
Explain 3 way handshake
Step 1: The initiating client requests a clientto-server communication session with the
server.
Step 2: The server acknowledges the clientto-server communication session and
requests a server-to-client communication
session.
Step 3: The initiating client acknowledges
the server-to-client communication session.
Explain session termination
Step 1: When the client has no more data
to send in the stream, it sends a segment
with the FIN flag set.
Step 2: The server sends an ACK to
acknowledge the receipt of the FIN to
terminate the session from client to server.
Step 3: The server sends a FIN to the client
to terminate the server-to-client session.
Step 4: The client responds with an ACK to
acknowledge the FIN from the server
How is data loss managed in tcp
- SACK (Selective acknowledegement) is applied
- If both host support SACK then it can be used, and SACK is used to explicitly acknowledge the packets that were received as well as any packets that were not received.
How is flow control managed in tcp
- When A sends segments to B and does not receive expected acknowledgements, it will reduce the size of the MSS until it receive ACK from B in order to reduce congestion
