Chapter 2 - Network Models Flashcards
What is the OSI Model
Open Systems Interconnection enables us to follow a model to explain almost any type of network including long obscure old ones.
Define Protocol
A set of rules, regulations, and standards that enable hardware and software developers to make devices and applications that will function at a particular level
What are the Seven layers of the OSI Model
7 = Application 6 = Presentation 5 = Session 4 = Transport 3 = Network 2 = Data Link 1 = Physical
What is a way to remember the seven layers (mneomonics)
All People Seem To Need Data Processing
What is part of layer one
Cabling, radio waves, central boxes (hubs, switches, etc.). Doesn’t care what the data is, only moves it from place to place
What makes a NIC unique
48 bit Media Access Control number made up of hexdecimal digits
What are the two parts to a MAC address
First 6 digits identify the manufacturer, Organizationally Unique Identifier
Last 6 digits identify the unique serial number
Who gives out MAC addresses
IEEE, Institute of Electronic and Electrical Engineers
How does Hexadecimal work with binary
Four bits = 1 character 0000 = 0 0001 = 1 1000 = 8 1111 = 15
What is the Organizationally Unique Identifier (OUI)
Used in the first 6 digits of a MAC address to identify the manufacturer
What is another name for MAC-48
EUI - 48 , Extended Unique Identifier
What is a frame
A container for a chunk of data moving across the network
Where is a frame created
The NIC
What does a frame look like
Recipient MAC | Sender MAC | Type | Data | FCS
What is FCS
Frame Checking Sequence, uses binary math (cyclic redundancy check) when recieving to verify that data is all intact
How much data can a frame contain?
1500 bytes (average)
How does a Hub operate
A hub makes an exact copy of the frame and broadcasts it to all system connected. The receiving system is the only one that will process the data.
How does a switch operate
Sends the frame to the proper destination only.
What is a way to think of Cyclic Redundancy Checks
It is similar to the remainder of a division problem
What is a broadcast address
FF-FF-FF-FF-FF-FF, every NIC will process this.
What is considered to be part of layer 2
Any device that deals with a MAC is part of layer 2
What does the Data link layer provide as a service
Data Link Control
What are the two jobs of the NIC
Logical Link Control, and Media Access Control
What is Logical Link control (LLC)
Talks with the system OS (usually drivers), handles network protocols and provides flow control
TCP/IP is considered a network protocol, but is actually…
a protocol suite, can be used to explain many protocols
What happens at layer 3
Containers called packets are created and addressed enabling them to go from one network to the other. This is the last layer that deals with hardware
What happens with an IP packet
Packet handed to NIC and enclosed within a frame.
What does a packet look like in contrast to a frame
IP Header | TCP Header | Segment
OR
IP Header | UPD Header | Message
Why would a packet be stripped away from the frame and put into a new frame
This is so it will be the appropriate technology for its next destination but the IP packet will never change
What connects the NIC to the System
Driver software
What happens in layer 4
Data is broken in to chunks called segments or datagrams depending on the protocol. Each chunk is given a sequence number. Think of it as the assembler disassembler software.
What happens in layer 5
Handles all the sessions incoming/outgoing in a system. Sessions are opened and closed here.
What happens in layer 6
Incoming data is translated to be used by software and applications, vice versa for outgoing
What happens in layer 7
This is the programming that enables application to be network aware.
What is encapsualtion
The process of preparing data to go onto the network
What is de-encapsulation
preparing data too be used by the system
What are the four layers of the TCP/IP Model
Application
Transport
Internet
Link/Network interface
What is a difference between OSI model and the TCP/IP Model
OSI is prescriptive, TCP/IP is descriptive
Explain the Link/Network interface layer (TCP/IP)
Similar to Layer 1 & 2 of the OSI model
Handles all the physical connections
Cabling, hubs, switches, etc.
Explain the internet layer (TCP/IP)
Any device or protocol that deals with pure IP packets.
Any device or protocol that deals with getting the IP packets to its destination.
Similar to the Network layer of the OSI model
Expalin the Transport layer (TCP/IP)
Combines Session and Transport (hint of application) from the OSI model
Involved in the assembly and disassembly of data
What is a connectionless protocol
TCP, Transmission Control Protocol
What is a connection oriented protocol
UDP, User datagram protocol
What si a TCP segment
What is left after a the IP is stripped from an IP packet. Make sure data gets to the destination in the right order using a checksum, flags, and acknowledgment.
What does a TCP segment look like
Destination Port | Source Port | Sequence Number | Checksum | Flag | Acknowledgement | Data
Where does TCP get is data from
The transport layer (OSI) or internet layer (TCP)
What does UDP get its data from
Applcation layer
What does a UDP datagram look like
Destination port | Source Port | Length | Checksum | data
What is the range of prots TCP/IP uses
1 - 65535
Link layer matches with which data structure
Frame
Internet layer matches with which data structure
IP packet
Transport layer matches with which data structure
TCP/IP segment or UDP datagram
Application layer matches with which data structure
Data starts and ends here
What does an IP Header contain
Source IP Address & Destination IP Address
What does a TCP/UDP Header contain
Source Port & Destination Port
