topic Re: Communication between two VLAN'S in Switching

Communication between two VLAN'S

ankitohc — Tue, 25 Jul 2023 23:19:52 GMT

Hello Team,

Can two different VLANs on the same switch communicate without trunking?

Is it possible?

For an example fa/01 to 10 vlan 10 and fa/11 to 20 vlan 20

Ankit

Re: Communication between two VLAN'S

MHM Cisco World — Tue, 25 Jul 2023 23:34:05 GMT

Sure yes

Only

Ip routing <<- this make l2 sw l3 sw ( you need assing ip for vlan svi in sw' the svi IP must be in same subnet of pc)

What you need to add

Re: Communication between two VLAN'S

Flavio Miranda — Tue, 25 Jul 2023 23:31:36 GMT

Hi @ankitohc

In a layer3 switch is possible but you need to create interface vlan for each vlan. For exampl

Int vlan 10

Ip address 192.168.10.1 255.255.255.0

Int vlan 20

Ip add 192.168.20.1 255.255.255.0

ip routing

Then, you need to assign ip address and gateway to PC. The gateway must be the ip address for the interface vlan.

If your switch have no layer3 cabability, you are going to need a router.

Re: Communication between two VLAN'S

ankitohc — Tue, 25 Jul 2023 23:39:09 GMT

Okay so it's possible but that is not a standard practice that we follow in day-to-day operations activities?

Re: Communication between two VLAN'S

Flavio Miranda — Tue, 25 Jul 2023 23:46:05 GMT

Actually it is. Most companies now a days have layer3 switch.

Re: Communication between two VLAN'S

MHM Cisco World — Tue, 25 Jul 2023 23:46:58 GMT

It depends

Re: Communication between two VLAN'S

ankitohc — Tue, 25 Jul 2023 23:50:21 GMT

But we usually set the router IP address as the default gateway, not the switch, right?

Re: Communication between two VLAN'S

MHM Cisco World — Tue, 25 Jul 2023 23:51:53 GMT

That why I mention it depend

If you have sw and router or fw then gw is router or fw

No need inter vlan in sw

Re: Communication between two VLAN'S

MHM Cisco World — Tue, 25 Jul 2023 23:53:34 GMT

If you have three layer data center

The access layer no need inter vlan

The distribute or core layer need inter vlan.

So you need to know how config inter vlan and use it when you network need it

Re: Communication between two VLAN'S

Flavio Miranda — Tue, 25 Jul 2023 23:56:16 GMT

In the scenario I describded, there will be no router. The layer3 switch do both function.

But, if you are studying for CCNA certification, for example, is is very usuall they do this using a router and a switch. For leaning purpose, they prefer keep router doing routing and switch doing switching. Thats why you may see the router as the gateway.

Re: Communication between two VLAN'S

ankitohc — Wed, 26 Jul 2023 00:57:29 GMT

How to communicate with PC0 to PC3?

PC0 is on VLAN 10 and PC3 is on VLAN 20

Re: Communication between two VLAN'S

ankitohc — Wed, 26 Jul 2023 00:59:29 GMT

Re: Communication between two VLAN'S

MHM Cisco World — Wed, 26 Jul 2023 01:02:05 GMT

Many issue in your network' first vlan10 and vlan20 have same subnet.

What is ip between sw and router?

And lastly I am sorry I can not help you in pkt' may be other can help you.

Thanks

MHM

Re: Communication between two VLAN'S

ankitohc — Wed, 26 Jul 2023 01:19:46 GMT

its okay I will figure it out myself... thank you for your help

Re: Communication between two VLAN'S

Flavio Miranda — Wed, 26 Jul 2023 01:51:19 GMT

@ankitohc you using the same network 192.168.1.0 255.255.255.0 . This is a problem.

You need to assign different networks for each vlan example

Vlan 10 - 192.168.10.0

Vlan 20 - 192.168.20.0

Then, you put the port between switch and router as trunk

On the router, you need to configure subinterface and each subinterface will represent one vlan.

You can send this PacketTracer file and I can show you. You just need to zip the file first.

Re: Communication between two VLAN'S

ankitohc — Wed, 26 Jul 2023 02:02:09 GMT

Please see attached pkt file in zip file..

Re: Communication between two VLAN'S

Flavio Miranda — Wed, 26 Jul 2023 02:15:14 GMT

So, here is a file where you can ping from one PC to another.

This scenario you built is the classic scenario called Router in a stick, very used to practice concept of Vlan, trunk, subinterface and routing between vlans.

Pay attention on how I setup the router. See that the interface does not have Ip address but instead the subinterface have.

Each subinterface is the gateway for each vlan and we use "encapsulation dot1q" which means trunk on the router side. On the swich side we need to change the interface from access to trunk.

Let me know if you undestood and ask if you dont

Re: Communication between two VLAN'S

ankitohc — Wed, 26 Jul 2023 02:37:32 GMT

@Flavio Miranda it was really helpful since I was not aware of subinterfaces... Good learning..

Now if we don't do trunking which we have done on the router and want to communicate between the two VLANs?

Re: Communication between two VLAN'S

Flavio Miranda — Wed, 26 Jul 2023 02:42:40 GMT

With one switch would not be possible. What you can do is use two switches and connect one switch to interface

GigabitEthernet0/0/0 and connect other switch to GigabitEthernet0/0/1.

On this case you dont use trunk and you can add the IP address on the interface directly, you dont use subinterface.

The scenario would change to something like this