Saturday, January 6, 2018

Layer 2 & Layer 3 switches

I'm pretty new so please bear with me.

There was a situation that requested to have certain ports to be configured into a specific vlan. (This occurs when there's a new set up with these machines in a different location but require a specfic vlan to get an ip address; trying to be vague in order to not pin point where I work at) I usually use switchport access vlan (vlan name) and call it a day.

However, i noted that the vlan doesn't reside in that switch and when searching for all vlans, it wasn't listed there. Usually I would attempt to trunk the port by checking cdp neighbors but wasn't too comfortable with it. I asked my co worker to help, and our lead mentioned that it's a layer 2 switch and that vlan doesn't reside on that layer 2 network. After back and forth name calling and bashing from the other department who made that original request, they resolved the issue. (my assumption is that they plugged into the layer 3 switch instead).

This is what I know for sure before this hooplah happened: I know that VLANS are layer 2. I know layer 3 has IP addressing.

The switches were: 3560a, and 3750xa

Are the layer 3 switches allows the VLANS to pass traffic across a trunk through routing but the layer 2 switch can't do that feature?

I'm trying to understand this better so when I have to explain it, not only does it make sense to me but I can interpret my answer multiple different ways because not everyone can understand one way of answering a question.



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