Saturday, April 20, 2013

10BASE-T AND 100BASE-T Pin Pairs

Group A
Transmit on 1, 2 and receive on 3, 6:

PC NICs
Routers
Wireless Access Points (Ethernet Interace)
Networked Printers 


Group B
Transmits on 3, 6 and receive on 1, 2: 

Hubs
Switches


You'll need a straight-though cable between Group A and Group B
You'll need a crossover cable between any devices belonging to the same group


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OSI Reference Model

Seven Layers:

7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data-link
1. Physical


Application: acts as the interface between the software and the network

Presentation: defines and negotiates data formats and also Encryption

Session: defines how to start, stop and control conversations

Transport: data-delivery and data-recovery

Network: Logical addressing, routing and path determination

Data-link: defines the format of the header and the trailer

Physical: deals with standards from other organizations, physical characters of transmission mediums.

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OSI vs TCP/IP




OSI                                                           TCP/IP
Application                  ->                        Application
Presentation
Session


Transport                    ->                        Transport

Network                     ->                        Internet

Data-link                     ->                        Network Access
Physical




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Friday, April 19, 2013

Data Encapsulation

Data Encapsulation is a 5-step process in TCP/IP Protocol Architecture

Starts at :
Application layer -> 
Transport layer -> 
Internet Layer -> 
Network access layer -> 
Transmission of bits occurs


Remember:
Network access layer - Frame
Internet layer - Packet
Transport layer - Segment
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TCP/IP Protocol Architecture

Remember: 
Each layer provides a service to the layer above it.


There are four layers:

1. Application. Example: HTTP, POP3, SMTP

Acts as the interface between the software running on a computer and the network.
Most common example is the Browser

2. Transport. Example:  TCP, UDP

TCP provides a mechanism to guarantee data delivery by using a data-recovery feature.

3. Internet. Example: IP 

IP defines addresses so that each host can be found and data can be delivered to it. 

4. Network Access. Example: Ethernet, Frame Relay.

Defines the protocols and Hardware required to deliver data across the network.

Remember:
Same-layer Interaction on different computers 
Adjacent-layer Interaction on same computer

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