Layer 2 and 3

Okay Maybe I need to reread chapter 1 and 2 on the Cybex book. I still dont quite understand the difference of 2 layers. Why some Router is considered layer 2 and some is layer 3? Can anyone point me to a quick web article that explains this?

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Comments

brad-

Routing is layer 3. Switching is layer 2, but some switches can be a layer 3 - which means it does routing and switching.

networker050184

Do you know the layers of the OSI model? Do you know what addresses correspond to those layers?

SteveO86

Definitely refer back to the OSI model, eventually you will have that memorized.

Switches work at layer 2, since switches rely on CAM tables and MAC addresses, to forward the traffic to specific hosts. You can read up on ARP requests and CAM tables for more information.

Routers work at layer 3, since they rely on (ip) routing table to forward traffic. Many routing protocols cover this topic. (You'll get to these later on)

The middle group is a Layer 3 Switch, this is essentially a switch that is capable of routing traffic by IP and not just by layer 2 information (MAC addresses and default gateway)

Note: As you read further the differences will become more apparent, and routers work at Layer 3 not 2.

VinUnleaded

networker050184 wrote: »

Do you know the layers of the OSI model? Do you know what addresses correspond to those layers?

Well I reread the Encapsulation section in Chapter 1. I think I got it now. Thanks for clearing it up guys