6. Reliable Communication Flashcards
1
Q
How does TCP ensure a reliable transmission?
A
- 3 way handshake
- sequence numbers to ensure order and nothing is missing
- acknowledgement numbers to confirm reception of packets, contains next expected sequence number
- time-out triggers a retransmission
- checksums to ensure integrity
- flow control to prevent overrunning the receiver, reducing packet loss
2
Q
Which application protocols run over TCP?
A
- ssh
- http(s)
- IRC
- SSL
- Transport Level Security
3
Q
What duplex is TCP?
A
Two way full-duplex, like a telephone call. Only unicast though.
4
Q
What is a problem with having sequence numbers in TCP?
A
The next one can be predicted by Trudy, interecpted or could send a new message with that sequence number.
5
Q
Disadvantages of TCP over UDP?
A
- bigger header size
- congestion control means data doens’t always get sent immediately
