Posts Tagged ‘osi’

Data Link Layer

2 primary functions:

1. Prepares L3 packets for transmission.
2. Controls access to the physical media.

Accessing the media:

A L3 exchange may involve many L2 and media transitions.
At each hop, routers decapsulate and re-encapsulate frames to match the right media.
The L3 protocol is not aware of which media is used.
L2 includes many types of media and access methods (eg. how it is getting to the wire).
L2 protocols specify the frame type and how to get a frame on and off each medium (media access control method, MAC method).
Devices use adapters to connect to a network (eg. NIC)
The adapter manages the framing and media access control (generates the signal transition).
Routers have different physical interfaces that frame the data as suitable for each link.

Read the rest of this entry »

Tags: guides, vlan, router, wan, ip, switch

OSI Transport Layer:

Transport Layer

Accepts data from Application layer and prepares it for layer 3;
Responsible for end to end transfer of data.
Enables multiple applications to communicate simultaneously.
Ensures data received reliably and in order.
Employs error handling mechanisms.

Read the rest of this entry »

Tags: cisco, 802.1q, guides, router, vlan, ip