[ALUG] Can anyone point me at a VLAN tutorial aimed at small 'soho' users?

Chris Green cl at isbd.net
Wed Jun 7 18:05:39 BST 2017

I'm trying to use VLANs to separate areas of my home LAN, mostly for
security by, for example, keeping guest/Windows WiFi connections
isolated from the rest of the system.

It appears that just about every manufacturers' idea of what VLAN
means is different!

I have VLAN ability offered by my TP-Link VDSL router, by my Draytek
Vigor 2820n router and by a TP-Link TL-SG108E managed switch.  They all
seem very different!

On the TP-Link router (TD-W9980) the VLAN facility is closely
connected with what it calls LAN groups.  You can create groups and
put the physical LAN ports and WiFi SSIDs into specific groups.  Each
group has its own DHCP server and thus a different IP range.  You
can't put anything (LAN port or SSID) into more than one group.
In reality there seems to be little real separation between groups as,
if you put (say) LAN port 2 into a group by itself any device
connected to LAN port 2 will still get replies DHCP requests it sends
from any/all the other LAN ports.  A different subnet will run on LAN
port 2 but if you configure a device connected to that port with a
different subnet address it will happily talk to devices on the other

The 2820n is quite different.  If you set up VLANs on that they all
have the same DHCP server (in the 2820n) and are thus on the same
subnet, but they are separated and unable to communicate with each
other.  Devices can be assigned to multiple ports.  Thus it's possible
to have one VLAN (to which everyone can belong) that has access to the
internet and not much else and another VLAN which is the more secure
internal VLAN.

Finally the TL-SG108E offers three sorts of VLAN - Port based, tagged
and MTU (confusing abbreviation that last one, it doesn't mean Maximum
Transmission Unit).  The manual isn't very helpful, it does the usual
TP-Link thing of repeating what the words on the GUI confuguration
tell you with no indication of *why* you would want to do anything.
Port based VLANs are a bit like the 2820n ones described above except
that they seem to expect different subnets, the others I'm not really
sure about (as in I don't really understand them) but looking around
the internet I gather that the descriptions confuse others too because
they don't use the same terms for the same things as others (mostly
Cisco) do.

Help!  :-)

I just need a simple explanation of how to split up my LAN such that I
can separate a 'Guest WiFi' part (more than one WiFi device), an area
that all local users can access (with printer, DNS, etc.) and a more
private area (my desktop, backup system, etc.) that only I can access.
All users need access to the internet of course.

Chris Green

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