How can I configure a layer 2 switching? and a layer 3 switching? What are their difference?
Lets say I have this setup:
access(2950)-->Distribution(3750)-->2 redundant Core switch(6500)
Thanks in advance.
L2 switching = classic LAN switching based on MAC addresses and L2 broadcast domains (Vlans)
in your case the C2950 probably acts only as L2 switch.
You need to setup the correct ports to Vlans associations and to configure correctly the trunk ports to Distribution.
if VTP is used you need to setup it as VTP client
L3 switching a.k.a. as multilayer switching (see other thread of today) provides the capability to perform inter-vlan routin in an efficient way.
In your case it is configured likely at distribution layer.
For each L2 broadcast domain Vlan a L3 logical interface SVI Vlanx is configured to provide routing services to users in this Vlan.
Distribution to Core can be done with L3 only links.
Hope to help