05-30-2006 10:40 AM - edited 03-03-2019 03:26 AM
Hi,
whats the difference between layer 2 VLAN and Layer 3 VLAN.
regards
Neo
05-30-2006 10:59 AM
a VLAN is a VLAN...no matter what layer they call it.
basically a VLAN is a layer-2 entity.
if you have what may be called a "layer 3 VLAN" then what you actually have is:
1) a layer 2 VLAN
2) a router (usually in the switch itself) configured with a VLAN interface to perform VLAN routing.
VLAN routing is required when you need a device in one VLAN to communicate with a device in another VLAN.
(remember, both VLANs in this case are still layer-2, they just also have a layer-3 interface/ipAddress to be used as routing interfaces)
05-30-2006 11:03 AM
Hi,
Thanks for your response , actually i am aware of this , but i thought that there might be some other defination for Second layer VLAN and third Layer VLAN.
regards
Neo
05-30-2006 11:23 AM
Here's the IEEE 802.1 defintion of VLAN. This is basically your layer 2 VLAN.
Provides for the logical grouping of stations (MAC Service Access Points - MSAPs) and/or switch ports, allowing communications as if all stations/ports are on the same physical LAN segment. This includes stations/ports that are physically located on different LANs or segments within the physical boundary of an 802.1D Bridged LAN. A single Bridged LAN may include multiple VLAN segments.
With that said, as the previous poster mentioned, for a host on a VLAN to communicate with a host on another VLAN you need a layer 3 device (router). Often, this is done by a layer 3 switch (like 3550, 6500 etc.). On a layer 3 device you have to create a logical interface, vlan interface on a switch or sub-interface if you are doing router-on-a-stick, to route traffic between VLANs. This is basically your layer 3 VLAN (interface) if you like to call it that way.
HTH,
Sundar
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