OSI & TCP/IP MODEL REVIEW

DISCLAIMER:

If you think you know it all, don’t shout out the answers! Go here:

http://www.gocertify.com/games/osi-game.shtml

http://www.funtrivia.com/playquiz/quiz2696101ede0b8.html

http://www.purposegames.com/game/osi-model-layers-and-darpa-layers-quiz/info

Review:

List the 7 layers of the OSI model on your paper. Don’t cheat, don’t tell your neighbor. NO LAPTOPS (2 minutes)

List the 4 layers of the TCP/IP model on your paper. Don’t cheat, don’t tell your neighbor. NO LAPTOPS (1 minute)

All together now

A P S T N D P

Application Presentation Session Transport Network Data Link Physical

Mnemonics

All People Seem To Need Data Processing (7 to 1)

Please Do Not Take Sausage Pizzas Away (1 to 7)

Pew! Dead Ninja Turtles Smell Particularly Awful! (1 to 7)

Layer 1: Physical

Physical transmission of bits. This layer generally defines the transmission medium, such as the standard of cabling used, pins, electrical currents, light modulation, etc.

Devices:-hubs, repeater, cabling

Protocols:-RJ-45, IEEE 802.3

Layer 2: Data Link

Defines the rules (protocols) that determine when a device can send data over a particular medium. Data link protocols also define the format of a header and trailer that allows devices attached to the medium to send and receive data successfully. (FCS field, etc)

Devices:-switches, wireless access points

Protocols:-ARP, CDP, 802.11, Frame Relay, PPP, STP, etc.

Layer 3: Network

Logical addressing, routing (forwarding), and path determination. Define how devices forward packets to their final destination. Logical addressing defines how each device can have an address that can be used in routing. Choosing best path.

Devices:-routers

Protocols:-IP

Pop Quiz:

How is a router different from a switch?

How is a router different from a bridge?

How is a switch different from a bridge?

How is a hub different from a switch?

Hub: dummy device-forwards any incoming traffic out all ports (except the one it came in)

Bridge: acts as a bridge in a network. If traffic attempts to cross that does not have a proper destination, YOU SHALL NOT PASS!

Pop Quiz:

How is a router different from a switch?

How is a router different from a bridge?

How is a switch different from a bridge?

How is a hub different from a switch?

Layer 4: Transport

Data delivery to another computer, data ensurance (error recovery, flow control)

TCP: Transmission Control Protocol•3-way Handshake•Ordered Transmission of Bits•Used for: anything where order and accuracy matter

UDP: User Datagram Protocol•No error-checking•Used for: streaming data (VoIP, video)

•Reserved ports for protocols

Layer 5: Session

Defines how to start, control, and end conversations (called sessions). Includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed. This allows the presentation layer to have a seamless view of an incoming stream of data.

Function:Starts, stops, maintains order

Note: Layers 5-7 generally share the same protocols, but most often are referenced in Layer 7

Layer 6: Presentation

Define and negotiate data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption also is defined by OSI as a presentation layer service.

Function:Encryption, data conversion, ASCII to EBCDIC, BCD to binary, establishing file formats, etc

Layer 7: Application

Provides interface between the communications software and any applications that need to communicate outside the computer on which the application resides. Also defines processes for user authentication.

Devices:-firewall, intrusion detection system

Protocols:-Telnet, HTTP, FTP, SMTP, POP3, VoIP, SNMP

TCP/IP

For next week:

Know the layers of the OSI and TCP/IP models.

Be able to describe the functions and/or basic protocols of each layer

Name the devices that operate at each layer

Know the cabling standards discussed: speed, IEEE standard name, cable type, etc.