Routers

they say routers work on the Network Layer .. what does it means?

This refers to the OSI model. There are seven layers and network is one of them. To truly understand what this means, take a peek at this link:

http://www2.rad.com/networks/1994/osi/layers.htm

--TH13

Actually not to confuse but they can work at both layer 2 (data link) and layer 3 (network layer). Both layers use addressing. IP addresses are associated with the network layer and physical (mac) addresses are associated with the data link layer. Some routers can preform bridging functions to segment different parts of a lan therefore also working at layer 2.

The Network Layer can most easily be understood by the word Network. Routers separate networks and subnetworks and directs packets between them. Another device that also works at the Network layer are Level 3 switches. The "routers" that are commonly sold to people for their home network are actually Level 3 switches. The call them routers because they have router capabilities in its software(NAT). In other words they are switches that think they are routers.

Bridges and repeaters and hubs work at the Data Link layer.

Quote:

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Originally posted here by One Who Watches
Bridges and repeaters and hubs work at the Data Link layer.

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Bridges do operate at the data link layer, however hubs and repeaters operate at the physical layer as they perform no intelligent function, they just retransmit and amplify the recieved data.