Archive for 25 July 2008

OSI Data Link Layer [layer 2] 25 July 2008 at 10:34 pm by admin
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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.

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

+ Planning & Cabling Networks By admin 25 July 2008 at 12:19 pm and have Comments Off

Planning & Cabling Networks

Media Required to Make a LAN Connection:

LANs use gateways to connect o other networks.
They use hubs or switches to connect end devices.
Each port on a router connects to a different network.
Routers break up broadcast domains and collision domains.
Routers can have both LAN and WAN interfaces.

Intranetwork Devices:

Hub

Receives signals, regenerates and sends them over all ports.
Creates a logical bus (i.e. multi-access media, everybody is on the same wire). [topologies].
Shared bandwidth approach – reduced performance (only one device can talk at a time).
A single collision domain.
Less expensive than switches.

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Tags: switch, ip, 802.1q, vtp, vlan, study