L2 and L3 Vlans

[kr_madan]

Hi All,

What is the difference between L2 VLAN and L3 LAN?

Regards,

Madan.

[farkascsgy]

Layer 2 interface is operate in Data link layer, so this interface doesn't have IP address.

Layer 3 interfaces have IP addresses.

If you use on a multilayer switch only L2 Vlan interfaces eg. VLAN 10 and VLAN 15, between the two VLAN you can't transfer traffic, but if you use Layer 3 interfaces the multilayer device can route between the two interfaces.

Just imagine that in case of Layer 2 interface you will not reach Network layer only Data link layer...

So if the goal is pass traffic between VLANs you need use Layer 3 interfaces (SVI) and if the goal is separate the VLANs you need use Layer 2 interfaces.

bye

FCS

Please rate me if I helped.

[pnschurr]

The real answer is... there is no such thing as an L3 LAN. It is a marketing concept invented by Cisco.

A LAN is a LAN is a LAN. It means Layer 2. Read 802.3.

If you attach a Layer 3 interface (such as an IP address) to a LAN, the LAN is still a layer 2 connectivity model and operates the same way.

In Cisco marketing speak, a Layer 3 Switch is actually a router. It probably has the look and feel of a Layer 2 switch, and can function as a switch, but can route (at Layer 3) between LANs.

Again, in Cisco marketing speak, MLS is Multi-Layer-Switching - which simply means switching at L2 in different LANs, AND routing between LANs and other routers at L3.

The whole 'L3-Switch' terminology (afaik) came about with CEF - which Cisco called switching to make it sound better than routing.

peter