Layer-2 Network

[Arjun Dabol]

Hi,

its a very basic switching doubt.

can someone help me understand what is the meaning when we say ..... " its just a layer-2 network " ...?  Because today's network have IP address configured on all the devices so why we still say Layer-2 network.

switch-B  (ip address)

|

|

Switch - A (ip address)

|

|

Hosts (ip address)

[Julio E. Moisa]

Hi 

Layer 2 networks use the MAC addresses to send data on a local area on a switch, Now there are switches multi layer, they can work on layer 2 and layer 3 at the same time. A layer 2 network is built by layer 2 switches or bridges only.

The layer 2 switches can have a management IP but they are unable to run routing tasks by themselves, a layer 3 devices is required for routing. 

Hope it is useful.

:-)

[Joseph W. Doherty]

An IP address on a L2 switch, as also noted by Julio, is for management of the switch.  I.e. it's basically just another host IP, where in this case, the host is a L2 switch.

For " its just a layer-2 network " would imply the network does not use any L3 routing.  Your hosts, on a L2 only network, should also work with Ethernet hubs and/or dumb/non-management switches.

[Richard Burts]

To look at this question from a slightly different perspective let us start from a fundamental concept:

a layer 2 network does forwarding using layer 2 MAC addresses.

a layer 3 network does forwarding using layer 3 IP addresses.

With that is mind I would say that the answer to the original post is that when you say it is just a layer 2 network then you are saying that it is a network that forwards traffic using the MAC address and ignoring the IP address. So functionally in this network all devices are in the same IP network.

HTH

Rick