Week 3: Overview of Networking Concepts Flashcards
Granting one party exclusive access of a shared transport path
impractical because it can delay all other parties
packet switching
They share by taking turns
To avoid long delays, the amount of data that can be transferred on a turn is limited
The unit of data that can be transferred at one time is called a packet
Two addresses are contained in the header of a packet
The source address (where the message came from)
The destination address (where the message is going)
A communication protocol is
an agreement that specifies a common language two computers use to exchange messages
The term comes from diplomacy
A computer communication protocol defines
The exact format and meaning of each message that a computer can send
The conditions under which a computer should send a given message
How a computer should respondwhen a message arrives
A computer communication protocol defines
The exact format and meaning of each message that a computer can send
The conditions under which a computer should send a given message
How a computer should respondwhen a message arrives
Encapsulation is
the addition of a header, and possibly a footer, to the data received by each layer from the layer above before it is handed off to the layer below
Open Systems Interconnection (OSI)
Each layer both performs specific functions to support the layers above it and uses the services offered by the layers below it
The three lowest layers focus on passing traffic through the network to an end system (hardware/firmware)
The top four layers come into play in the end system to complete the process (software)
Who standardized OSI Model
ISO (International Organization for Standardization)
Layer 1
physical layer
connector and interface specifications
medium (cable) requirements
electrical, mechanical, functional, and procedural specifications for sending a bit stream on a computer network
Physical Layer components
Cabling system components Connector design and pin assignments Hub, repeater, and patch panel specifications Wireless system components Network Interface Card (NIC)
Layer 2
data link layer
Allows a device to access the network to send and receive messages
Offers a physical address so a device’s data can be sent on the network
Works with a device’s networking software when sending and receiving messages
Provides error-detection capability
Layer 2 components
Network interface cards (NICs)
- NICs have a layer 2 or MAC address (Media Access Control)
Ethernet and Token Ring switches
Bridges (similar to switches)
- normally work in software
switches
- switches use Application-Specific Integrated Circuits (ASICs) to perform the task on dedicated hardware
Layer 3
Network layer
modelprovides an end-to-end logical addressing system so that data packets can be routed across several layer 2 networks
Layer addresses can also be referred to as logical addresses
The Internet Protocol (IP)addresses make networks easier to both set up and connect with one another
Some basic security functionality can also be set up by filtering traffic using layer 3 addressingon routers or other similar devices
Layer 3 components
Router
When passing packets between different networks, it may become necessary to adjust their outbound size to one that is compatible with the layer 2 protocol that is being used
Routers at the network layer accomplish this via a process known as fragmentation
Layer 3 protocols
Routing Information Protocol (RIP)
Open version of Shortest Path First (OSPF)
Layer 4
Transport layer
of the OSI model offers end-to-end communication between devices through a network
Depending on the application, the transport layer either offers reliable, connection-oriented or connectionless, best-effortcommunications
Layer 4 protocols
the connection-orientedTransmission Control Protocol (TCP)
the connectionlessUser Datagram Protocol (UDP)
Layer 4 functions
Client-side entity identification
- Transmission-error detection
- Confirmation that the entire message arrived intact
Segmentation of data for network transport
Control of data flow to prevent memory overruns
Establishment and maintenance of both ends of virtual circuits
- Realignment of segmented data in the correct order on the receiving side
Multiplexing or sharing of multiple sessions over a single physical link
Layer 5
Session Layer
establish, manage, and terminate a dialog through a network
Layer 5 functions
-Virtual connection between application entities
Synchronization of data flow
-Creation of dialog units
Connection parameter negotiations
Partitioning of services into functional groups
Acknowledgements of data received during a session
Retransmission of data if it is not received by a device
Layer 6
Presentation Layer
how an application formats the data to be sent out onto the network
Layer 6 functions
Encryption and decryption of a message for security
Compression and expansion of a message so that it travels efficiently
Layer 7
Application layer
an interface for the end user operating a device connected to a network
Layer 7 functions
Support for file transfers
Ability to print on a network
Electronic mail
Browsing the World Wide Web
TCP/IP Layers with UDP
Application Layer (Application, Presentation, Session) Transport Layer (Transport Layer) Internet Layer (Network Layer) Network Interface Layer (Data Link, Physical)
TCP/IP Layers with TCP
Application Layer (Application, Presentation) Transport Layer (session, Transport Layer) Internet Layer (Network Layer) Network Interface Layer (Data Link, Physical)
Network Interface Card
The networks may use different technologies
The computer can send or receive packets on any of the networks
The process of selecting a network over which to forward a packet
routing
Routers communicate with one another using routing protocols such as
Routing Information Protocol (RIP) and Open Shortest Path First (OSPF), to learn of other networks that are present and to calculate the best way to reach
Locations that connect directly to the backbone are called
backbone sites
tier 1 providers
Major ISPs that operate a backbone network
AT&T and Sprint are examples
tier 2 providers
Regional ISPs
tier 3 providers
Local ISPs
A connection between a pair of tier 1 providers is called a
peering arrangement
Tier 2 and 3 providers are___ a provider in a tier above them
customers of
Residential and business customers usually connect to
regional or local provider