Hi all,

anyone know if its possible to allow two LAN's to connect to a 2820N to share one ADSL connection ?

basically I have a small customer who runs a SBS server with standard email / fixed IP and SBS server giving out IP's on 192.168.1.x range

they recently aquired a 2nd company who will move into the same office.
this 2nd company has a few PC's in a workgroup configuration with next to no other setup.

For a bit of security we wish to run the 2nd company of its own LAN and keep it seperate from the SBS network

Looking at the 2820 it seems to support two subnets but how the heck you put this into practice without I would suppose a decent managed switch or two who knows!

So basically I want some machines on 192.168.1.x and 192.168.2.x connected to same internet connection, ideally retaining SBS dhcp server and either fixed IP for 2nd subnet or routers DHCP server.

cost is a issue for this setup so if any of the draytek routers can do this that would be a result, I would in most cases use something like a juniper SSG5 for the LAN side / routing but as these are not cheap it may be out of the question for a small company.

Thanks!
Neil

I have a V2910 but I think the V2820 will be similar.

I think what you want is the VLAN section in the setup page.

You can have up to 4 virtual LANs and designate the 4 ports on the back to define which port belongs to which VLAN.

So you can designate port 1 and port 2 as VLAN1 and port 3 and 4 as VLAN2 (or any other permutation you want).

Anything plugged into the ports designated as VLAN1 will not be seen by anything plugged into VLAN2 and vice versa.

I think both LANs will be on the same subnet (I can's see any way to specify different ones) but one will not see the other.

I have not used it myself so this is just theory.

Using VLANs as such won't provide the solution, as you can't run two separate subnets on the DrayTek and you can't have two DHCP servers. The SBS will be the DHCP server for its own subnet, so you can't enable DHCP on the DrayTek.

The best way to approach this, I suggest, is to use a second router - a cheap domestic router will normally do - with an RJ45 WAN interface (i.e., one suitable for use on cable) which you plug into a LAN port of the 2820 and isolate that port into its own VLAN providing only internet access through the DrayTek.

Give the second router's WAN port a fixed IP address from the 2820's subnet, set it's LAN side to the subnet of choice and make it a DHCP server. You will end up with double-NATting on the workgroup subnet, but this will only be an issue if you are using port forwarding to the workgroup.

Sorry, I missed the bit about the server having its own DHCP server.

If it were possible to change that and get both networks on the same subnet, it would make for a much simpler setup.

In a business environment in particular I would think simplicity should be the aim.

Don't take away the DHCP role from the SBS - this is definitely not recommended. You also don't want unmanaged workstations on a domain-based network.

I stand corrected. Please excuse my ignorance, but what difference is there whether the router or server provides the DHCP service?