Multiple VLANS with the same IP range and the same Subnet

[riki.marhadi]

Hi guys,

Basically I would like to install 3 separate networks with the same IP range and the same Subnet.

The purpose of this set up is to have 3 separate jobs running at the same time. ( Locally in the office before we send it to site )

Internet : 192.168.12.1/255.255.255.0

- Network 1:

Controller 1 : 192.168.12.101/255.255.255.0

Controller 2 : 192.168.12.102/255.255.255.0

Controller 3 : 192.168.12.103/255.255.255.0

etc

- Network 2:

Controller 1 : 192.168.12.101/255.255.255.0

Controller 2 : 192.168.12.102/255.255.255.0

Controller 3 : 192.168.12.103/255.255.255.0

etc

- Network 3:

Controller 1 : 192.168.12.101/255.255.255.0

Controller 2 : 192.168.12.102/255.255.255.0

Controller 3 : 192.168.12.103/255.255.255.0

etc

Can this setup be done using VLAN? 

I have SG350-10P cisco manage switch and be able to created multiple Vlan,

But couldn't set up the same IP range ( Vlan10 : 192.168.1.2 and Vlan20 : 192.168.1.2 )

Any advice please?

Is there any other ways to make this work without using VLAN?

I was thinking to add 3 more routers on the network.

So each Network will have their own router.

Will that work and act like VLAN to segregated the 3 networks?

Or if you have any thoughts, please let me know.

Appreciate your help.

Thank you.

Regards,

Riki

[Richard Burts]

I do not know anything about your environment and am not really clear about what you want to achieve. But based on the information in your post I suggest that the best solution is 3 routers.

You tell us "The purpose of this set up is to have 3 separate jobs running at the same time" It is not clear whether these jobs are self contained or whether they need access to resources that are external. Especially if they need access to resources that are external then routers can do Network Address Translation and each of the jobs can access external resources. If you try to do it with vlans and one job requested data then how would the external resource know which one to send the data to?

[riki.marhadi]

Hi Rick,

Thank you for replying my question.

In the job normally we will install bunch of smart controllers for BMS. Before we send it to the building to be installed, we will set up the configuration & system logic as much as we can in the office. ( Roughly around 2-3weeks sitting in the office network )

The controllers will connect with our cloud server. And we can access the controller remotely using internet.

If there is only 1 job at the time, there is no problem.

However, between 2-3weeks, there will be few jobs come in to be configured in the office.

We are trying to make all the controller in every job the same IP address for easier fault finding/investigate/etc in the future.

Master controller always 192.168.15.101.

2nd controller always 192.168.15.102

Etc

My goal is to have 3 networks segregated from each other, so I could have 3 jobs running at the same time which there will be 3 master controllers running at the same time ( 1 for each job ) with IP address 192.168.15.101.

All the 3 networks need access to the internet to be able to connected with cloud server.

Please don't hesitate to reply and give some advice how to achieve my goal.

Thank you.

Regards,

Riki

[johan.merello]

Hi, maybe you can work with dhcp on each network and on each site do you have the same network, because his gateway to be the  ip of master controller.

Other wayse is subnetting the network and create multi vlan.

Othe is to use one router or switch to each network and maybe use some type of NAT, because do you have the same network on 3 sites.

[Richard Burts]

Riki

Thanks for the additional information. We do not know much about your environment and there may be things that would impact our advice. But based on what we know so far I believe that if you use 3 routers it could work. Each router could have an interface that connects to your SG350 and other interface(s) that connect to the controllers. The router would need to do address translation for the controller addresses. This would allow 3 sets of controllers to run at the same time and to access your cloud server.

Some routers have interfaces that act as switch ports. If you use this type of router then the controllers could connect to the router (on a vlan that the router would configure). If you use a router that does not have interfaces that act as switch ports then you would need another switch to connect to the router and to the controllers.

[riki.marhadi]

Hi Rick,

Thank you for your response.

Looks like I will use 3 routers.

Do I need to buy specific routers that have NAT configuration? Any recommendation please? 

The main internet using Telstra business smart modem and the main router has 1 WAN and 4 LAN. 

This is roughly drawing that I would like to achieve.

Please don't hesitate to correct my thought if you think it is wrong.

Thank you.

Regards,

Riki

 

 

[Richard Burts]

Riki

Thanks for the additional information, and especially for the drawing. The drawing shows a network switch connecting the router to the controllers. If you have a network switch for each router then just about any router should do what you need. I might suggest that something as simple (and less expensive) as the Cisco RV160 could do what you need, and since its ports can be configured as access ports in a vlan that you do not need a separate network switch.

The main issue that I see is that you are using network 192.168.15.0/24 on both the upward facing (outside/WAN) interface and the downward facing (inside/LAN) interfaces. Cisco routers do not support having the same network/subnet on 2 different interfaces. A fairly simple solution could be to change the subnet mask from /24 to something smaller (perhaps /28). If you do this then the controllers can use the 101, 102, and 103 addresses while the outside/WAN interface could use a lower number.

[balaji.bandi]

The task you trying do with the switch it is not possible.

Not sure why you need overlap IP address here, if they all in same network you can use 1 VLAN right.

if you looking kind of setup,m then you need VRF or NAT in place...but this is over engineering for your switch.

[riki.marhadi]

Hi Balaji,

Thank you for your answer.

The reason why I want to overlapping the IP address is to be able to setup and running 3 different job at the same time.

This is will be temporary set up in the office before we send it to the site.

In the job normally we will install bunch of smart controllers for BMS. Before we send it to the building to be installed, we will set up the configuration & system logic as much as we can in the office. ( Roughly around 2-3weeks sitting in the office network )

The controllers will connect with our cloud server. And we can access the controller remotely using internet.

If there is only 1 job at the time, there is no problem.

However, between 2-3weeks, there will be few jobs come in to be configured in the office.

We are trying to make all the controller in every job the same IP address for easier fault finding/investigate/etc in the future.

Master controller always 192.168.15.101.

2nd controller always 192.168.15.102

Etc

My goal is to have 3 networks segregated from each other, so I could have 3 jobs running at the same time which there will be 3 master controllers running at the same time ( 1 for each job ) with IP address 192.168.15.101.

All the 3 networks need access to the internet to be able to connected with cloud server.

If using 1 VLAN, we can't have 3 master controllers running at the same time because they have the same IP address.

Yes looks like managed switch will not be able to do the task.

Any advice is welcome.

Thank you.

Regards,

Riki