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Wednesday, July 1, 2020

Tips #6 - Faking an Admin vlan on the Netgear GS108Ev3 and GS116Ev2

My network at home is distributed and I try to minimize the number of wires going throughout the house.  That becomes a problem if you are single switch dependent.  But with judicious use of vlans throughout the house, I can distribute these through the use of trunk lines.  One thing I am very conscious about is security in the network.  I make judicious use of Admin vlans in order to keep the network framework from being changed by someone who has hacked into my system.

I went out and bought a GS108Ev3 thinking it was a good and cheap alternative to the GS108Tv2.  Boy was I wrong.  My focus on security took a nose dive, or so I thought, when I started incorporating this switch into my network.  It was the same thing for the GS116Ev2 when I added this switch.  If you follow a simple set of rules, you can keep your Admin vlan:


  1. a normal Netgear managed switch like the GS108Tv2 has an Admin vlan capability.  In fact, you can actually put the vlan number into a field in the web interface.  The switch will use this vlan number to accept DHCP IP addresses for the switch.  If you fix the IP address of the switch, you will need to be in the subnet of the Admin vlan for the switch to work.
  2. there is a new class of Netgear switches, like the GS108Ev3 and the GS116Ev2 which are simplified but have much of the capabilities of the GS108Tv2.  One of the capabilities that is missing is the Admin vlan.  There is no field to set it and you are forced to use vlan 1 in some manner to interface to your network.  You do that on a trunk port
  3. On GS108Ev3/GS116Ev2: either use DHCP or set the IP address/Gateway to be within the Admin vlan subnet
  4. On GS108Ev3/GS116Ev2: set vlan 1 to be untagged on the trunk port; set the Admin vlan to be tagged on the trunk port; set the Admin vlan to be the PVID on the trunk port
  5. On GS108Tv2/M4100: set the Admin vlan to be the PVID on the trunk port; set the Admin vlan to be tagged on the trunk port
  6. On GS108Ev3/GS116Ev2: no other ports may have vlan 1 as untagged, except the trunk ports

Not a difficult configuration, but as long as you remember the rules you can get an Admin vlan on these GS108Ev3/GS116Ev2 switches.