I am trying to get my head around VLAN config. I have a load of Netgear GS728TP switches accross my site, and I'm trying to get some devices moved to alternative VLANs because I have exhausted the /24 network pool assigned currently.

I have got VLAN trunking working between switches, so my Visitor WIFI VLAN (50) is now able to have an ADSL router plugged into one switch, and on other swithes connected via trunk links there are APs putting clients onto VLAN 50 - they are able to get their IP address from DHCP on the ADSL router which is what I needed.

Now I am trying to move a bunch of about 30 IP cameras to VLAN 20. I need to be able to route between the IP cameras, and the NVR device which will stay on VLAN1 (well, it could move to VLAN20 once the routing is working..)

What I have done so far, is decide on 1 switch as my "master" - it's a GS752TP. I have setup an IP address of on VLAN20. What I can't do, is setup an IP address of on VLAN1, as it says that the IP address interface is duplicated.

In the ARP table of my master switch, I can see the single IP camera that I've addressed as and configured to be on VLAN20 - but I cannot ping it from either the master switch, or the one that it's plugged into - should I be able to?

Many Thanks Mark

  • Asking me to get the running config, has answered part of my question - the management IP that I'm using to connect with is already defined in vlan 1. I see that now from the config: interface vlan 1 ip address no ip address dhcp ipv6 address autoconfig interface vlan 20 name CCTV ip address
    – Mark Damen
    Commented Sep 12, 2017 at 20:51
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Commented Feb 21, 2018 at 16:23

3 Answers 3


It sounds as if you've duplicated subnets somewhere. You can't have overlapping subnets on two different VLANs. Check to make sure that VLANs 1, 20 and 50 are all different subnets.

I assume only the master switch has addresses on the VLAN interfaces. In that case, you should be able to ping from the master. You either have a trunking problem, or your addressing is wrong -- which might explain the first problem.

Posting the master switch configuration would be helpful to find the problem.


When you are setting up a VLAN with a subnet and wanted routed you need to set a Layer 3 interface which will act as the default gateway.

I'm unfamiliar with the netgear as I mainly work on cisco, but on a Layer 3 device you need to have the IP.

So it should look something like.

interface VLAN 1
  desc VLAN 1 
  ip address
interface VLAN20
  desc IP Cameras
  ip address

Once that is done you need to make sure the DHCP server is giving out the proper subnet mask and gateway IP.

Then make sure that the device is assigned to whatever VLAN you need.

IE, port 1/0/1 assigned to vlan 20 and so on.


Each endpoint, e.g. camera, must be configured with IP addressing info. This is best done automated by using a DHCP server which tells each device it's IP address, subnet mask, default gateway, DNS server(s), etc. Sometimes there are other optional parameters delivered via DHCP. Check your camera documentation for "DHCP option".

Other than that, it's basic networking. If you have changed the network device configuration, you might power cycle them as old configuration parameters can sometimes remain cached (in memory) and cause issues. Same goes for the endpoints. Hopefully your cameras are powered via PoE so when you reboot the network, you'll be rebooting the cameras too.

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