lecture 3 - transport layer

two common protocols in transport layer

-TCP (transmission control protocol)

-UDP (user datagram protocol)

3 transport layer functions

1) linking to the application layer

2) segmenting

3) session management

What layer does TCP/UDP link to?

Application layer

What do TCP and UDP serve?

Multiple application layer protocols

What identifies an application in TCP/UDP?

Ports (2-byte numbers)

What do many source/destination ports follow?

Standards

What is the common port standard for HTTP?

Port 80

What is the common port standard for SMTP?

Port 25

What is the common port standard for DNS?

Port 53

What is segmenting in networking?

Breaking large files into smaller segments.

How are segments passed to the application layer?

Segments are passed individually to the application layer after reassembly.

What does the segment size depend on?

The segment size depends on the network and data link layer protocols.

segmenting process

application layer sees message -> TCP breaks large message into smaller segments -> negotiations -> TCP puts packet back together at destination -> delivers incoming packets as they arrive

What is session management in networking?

It refers to the conversation between two computers or creating a virtual circuit.

What type of messaging is used for connection-oriented communication?

TCP (Transmission Control Protocol)

What type of messaging does not require establishing a session?

Connectionless messaging (UDP)

TCP connections 3-way handshake

1) request for TCP connection

2) transit segments

3) close TCP connection

-SYN, SYN-ACK, ACK

TCP (circuits)

makes end-to-end connections broken into segments sent in order, then retransmitted if negative acknowledgement is received

UDP (user datagram protocol)

connectionless protocol that does not require a connection to send a packet and does not guarantee that the packet arrives at its destination

wireshark

Application that captures and analyzes network packets

wireshark purposes

-troubleshoot network problems

-examine security problems

-quality assurance (QA) verify network applications

-debug protocol implementations

-learn network protocol internals