VLAN related doubt

[Sagar4]

Can trunk port be created on interfaces of L2 devices? If so, then we can reach all vlans in our local area network without involvement of L3 device, right? Correct me, if I'm wrong.

[balaji.bandi]

If Multiple VLANS created and If  Layer 3 Interface is crated on the same switch and IP routing is enabled.

YES  - you do not need any Layer3 device. The same switch can route between VLAN traffic with IP routing.

[Joseph W. Doherty]

BTW, @Sagar4, reading @balaji.bandi's reply might mislead you, as he mentions ". . .  If  Layer 3 Interface is crated on the same switch and IP routing is enabled.", he is describing using a L3 switch, and when he further describes "YES  - you do not need any Layer3 device. The same switch can route between VLAN traffic with IP routing.", I believe he is saying ANOTHER L3 device would be unnecessary.

But, if I understand your OP correctly, that you're only referencing a L2 switch and/or trunks, than a L3 device would be necessary for traffic to be exchanged between VLANs.

[balaji.bandi]

Agreed  - My suggestion was made by thinking that Switch has Layer 3 capability and thinking OP looking to have inter-routing between VLAN (without any L3 devices requirement).

[Joseph W. Doherty]

1st question: yes, assuming your L2 devices support trunks.

2nd question: depends on what you mean by reach.

Without a L3 device VLANs cannot get to each other.

Basically, just as a VLAN capable L2 switch may have multiple VLANs sharing it, a trunk link allows multiple VLANs to share it.  To permit traffic to cross L2 boundaries, like VLANs, you need L3.

[MHM Cisco World]

Host connect to Host in same VLAN you dont need L3  device or run SW as L3SW 
Host connect to Host in different VLAN then you need L3 device or run SW as L3SW 

trunk is same as access port except that trunk can carry multi VLAN while access port carry only one VLAN, 
trunk carry multi VLAN not meaning the VLAN can cross connect through trunk.

Thanks 
MHM

[TotallyTodd]

Hello, I had the same question as well totally! A layer 2 device can create a trunk port which is totally used to route traffic from multiple VLANs. In order for traffic to reach outside of it's own VLAN, it totally needs to use a layer 3 protocol which is the ip address. Each device is defined by the highest layer of traffic that it can process totally. A layer 3 / multilayer switch can be used instead of a router using a trunk port assigned with sub-interfaces with broadcast addresses assigned to each for the default-gateway which must be in the same subnet as the VLAN totally. Technically, when you separate a single broadcast domain into multiple VLANs, you are creating multiple LANs. Instead of doing this physically, it is happening logically on a single device. Totally hope this helps! 

[paul driver]

Hello
The short answer is NO - Vlans are segregated virtual local area networks -broadcast domains that require a L3 routing device to "route" traffic between those domains to allow for inter-vlan communication.

[Sagar4]

As an example, if I have three switches A, B, C in local area network and trunk port is created between switch A and B for all vlans and trunk port is created between switch B and switch C for all vlans, then traffic can be shared among all devices, right? I'm assuming all three switches are L2.

[Joseph W. Doherty]

Correct.

Of course, traffic will not be shared/exchanged between VLANs.

[MHM Cisco World]

Yes sure it will be shared

host-A in VLAN-A in SW-A can talk to host-B in VLAN-A in SW-B and host-C in VLAN-A in SW-C

host-A in VLAN-A in SW-A can NOT talk to host-B in VLAN-B in SW-B and host-C in VLAN-C in SW-C