Week 3 Transport Layer Flashcards
What is multiplexing?
Multiplexing is converting multiple signals of traffic into a single signal
What is demultiplexing?
Demultiplexing is taking the 1 multiplexed signal and converting it back to the separate, original signals back to the specific service using its port
What does the transport layer use to perform multiplexing and demultiplexing?
The transport layer uses ports to perform multiplexing
Describe what ports are?
Ports are a 16-bit number that direct traffic to specific services on a networked computer
What’s a socket address/socket number?
A socket address/socket number is the port number added to the end of an IP address through the use of a colon :
What is FTP?
File Transfer Protocol
an older method of transferring files between computers
What port does FTP listen on?
Port 21
What is a TCP segment made of?
TCP header and data payload
What does an Ethernet frame encapsulate?
Ethernet frame encapsulates IP datagram
What does an IP datagram encapsulate?
IP datagram encapsulates TCP segment
Name the 13 sections of a TCP segment
- source port 16
- destination port 16
- sequence number 32
- acknowledgment number 32
- header length/data offset field 4
- empty 6
- control flags 6
- TCP window 16
- checksum 16
- urgent 16
- options 0-16
- padding
- data payload (varies)
Why is a source port important?
Keeps communication lines organized and so the traffic knows where to come back to when it fetches data requested by the client
What does buffer mean?
A buffer is when data is held somewhere before being sent somewhere else
What are the 6 TCP control flags?
- URG urgent
- PSH push
- ACK acknowledge
- SYN synchronize
- FIN finish
- RST reset
Describe the 3-way handshake (control flags)
A sends SYN to B
B sends SYN/ACK to A
A sends ACK to B
