Protocols
How machines talk to each other even though hard/software is different
What are Packets?
At what layer are they used?
What are two examples?
- streams of bits running as electric signals on physical media used for data transmission
- ex: wire = LAN, air = wifi
Networking
exchanging information between networked computers
How are electrical signals interpreted?
through bits (0s and 1s) that make up the information
Structure of protocol packet
2 parts
header and payload
What’s the purpose of the packet header?
does 2 things
- has protocol-specific structure
- ensures receiving host correctly interprets payload and can handle communications
packet payload
contains actual info, ex: email message, file content
What does the IP protocol header contain?
How many bits is it?
- 160 bits (20bytes) long
- contains info to interpret content of IP packet
What do the first 4 bits of the IP header identify?
- identify IP version
- ipv4 or ipv6
What do the 32 bits of the IP header represent? (position 96)
represent source address
What do the 4 bytes after the source address in the IP header represent?
represent destination address
Protocol Layer[s] (4)
hint: ATNP
- Application
- Transport
- Network
- Physical
What’s the point of the Application Layer?
What are some examples?
Make application work
- ex: email client, ftp, browser
What is the purpose of the Transport Layer in relation to data/packets?
What is one main example?
Transport data between processes
- ex: between server and client programs
What does the Network Layer do?
Identify hosts/computers on a network
What is the Physical Layer’s relationship to packets?
Use physical media to send packets (transmit data)
What are the 7 OSI layers?
Are they used today?
ISO/OSI (open system interconnection)
7 layers, used as reference but never implemented
Physical, Data Link, Network, Transport, Session, Presentation, Application
How does Encapsulation work in relationship to packets and packet components?
- Entire upper protocol packet (header + payload) is payload of the lower one
- every packet adds its own header to the payload
What is another name for TCP/IP?
What is TCP/IP stack and where is it used?
- aka: IP protocol suite
- real world implementation of networking stack
- protocol stack used on the internet
What are the TCP/IP layers?
hint: 4, ATND
- application, transport, network, data link
What is the Internet Protocol in charge of delivering and to who?
How does it utilize IP addresses?
- in charge of delivering datagrams (packets) to hosts in communication
- uses IP addresses to identify a host
What is another name for a datagram?
aka: Internet Protocol packets
Where is IPv4 used?
How many bytes/octets?
- used by vast majority of networks
- 4 bytes / octets
- each byte has 8 bits
what network are the addresses 0.0.0.0 - 0.255.255.255 reserved for?
reserved for “this” network
