Network Models Flashcards
What are protocols?
rules, regulations, standards and procedures that allow hardware and software developers to make devices and applications that function properly at a particular layer
OSI Layers?
Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link Layer 1 Physical ( All People Seem To Need Data Processing )
What is UTP?
Unshieled Twisted Pair
What is Layer 1?
Physical
- defines method of moving data between computers
- central box, copper cabling, fiber optics, radio waves
What is a NIC?
Network Interface Card
- serves as the interace between PC and network
What is a MAC address?
Media Access Control Address
- 48 bit unique identifier
- also known as physical address
What is the OUI?
Organizationally Unique Identifer
- first six digits of a MAC address
- identifies manufacturer
What is the last portion of the MAC Address?
Device ID
See the mac address in Windows?
ipconfig /all (called physical address)
See the mac address in Mac?
ifconfig (called ?)
See the mac address in Linux?
ip a (called link/ether)
Other names for a MAC address?
MAC-48
EUI-48 (Extended Unique Identifier)
Unit of data at each layer is called?
Protocol Data Unit (PDU)
Can NICs on the same network use different types of frames?
No
What are the parts of a frame?
Header: - receiving MAC - sending MAC Payload: - Type field (indicates whats encapsulated in the frame) Trailer: - FCS (Frame Check Sequence)
What is the FCS?
Frame Check Sequence
- Uses a cyclic redundancy check (CRC) that the receiving NIC uses to determine if the data arrived intact
- 4 bytes long
- if CRC is wrong, frame is dropped
Size of a frame?
1500 bytes
Layer 2 Broadcast Address
FF-FF-FF-FF-FF-FF
A frame addressed specifically to another devices MAC address?
unicast frame
Layer 2?
Data Link Layer
- any device that deals with a MAC address
What is LLC?
Logical Link Control
- first job of the NIC, talks to the OS via device drivers
What is MAC?
not MAC Address
Media Access Control
- second job of the NIC that creates and addresses frames
What is logical addressing?
IP addressing
needs a network protocol
What does TCP/IP stand for?
Transmission Control Protocol/Internet Protocol
Layer 3?
Network Layer
- creates and addresses packets to go to another network
What is the PDU for layer 3?
Packet
Where is the MAC address stored?
Burned into chip on the NIC
Parts of an IP Packet?
- Destination IP
- Source IP
- Data
- enclosed in a frame
Layer 4?
Transport Layer
- segmentation (chops up data into chunks that will fit into packets) on sending NIC
- reassembly (reassembles data on receiving NIC)
- chunks are called segments (TCP) or datagrams (UDP)
- initializes requests for packets that weren’t recieved in good order
Layer 5?
Session Layer
- accepts, opens and closes all sessions
- connects applications to applications
- keeps track of all sessions
Layer 6?
Presentation Layer
- translates data from lower layers into a format usable by the application layer, and vice versa
Layer 7?
Application Layer
- the code built into application that make them network-aware
API?
Application Programming Interface
- a way for programmers to enhance or extend an applications capabilities
Preparing to send out and receive data on a network?
Encapsulation & de-encapsulation
View TCP connections in Windows?
netstat -n
Encapsulation at Layer 2
Frame
Encapsulation at Layer 3
IP Packet
Encapsulation at Layer 4?
TCP Segment / UDP Datagram
Encapsulation at Layer 7?
Data (or payload)
