Hi Everyone

I've inherited a network which has a Vigor 2820n but it's not being used to it's full potential. There are no VLANs and the all hosts on the network are in the range 192.168.10.0/24. It seems a waste of money to have such a sophisticated piece of kit and I'd like to learn more about the configuration for an imminent increase in size and complexity of the network.

I'm happy with setting up inter-VLAN routing using Cisco hardware in the CCNA lab using the Router-on-a-Stick configuration, but is this possible using the 2820n? For instance, I have enabled each of the four ports into separate VLANs and want to have the ranges 192.168.20.0/24, 192.168.30.0/24, 192.168.40.0/24 and 192.168.50.0/24. As far as I can see, I can have DHCP providing addresses for only two of these ranges so I could have a DHCP server on each of the other two LAN segments.

In addition to the inter-VLAN routing, I would like each of the four segments to be able to access the internet.

Is what I'm hoping for possible with the 2820n? If so, I'm happy to persist with my investigations and trial/error (unfortunately, the documentation that I've seen doesn't seem very helpful) but if it's not going to be possible, I'll abandon the idea.

Thank you for your time (and patience!).

If you want Cisco features, buy a Cisco :wink:

The 2820 VLAN is solely for port isolation from each other, nothing more: it doesn't stop the ports accessing the WAN or the DHCP server and DNS proxy of the 2820.

Thank you. Your news is disappointing but will stop me wasting my time trying to do something that's impossible!

So, if I have it right:

1. If I configure one port per VLAN, these VLANs are completely separate from each other but all can access the internet?

2. I know that I can have two DHCP servers providing addresses on the 2820n but how do I specify exactly to which of the four ports (hence VLANs) the DHCP servers provide addresses? As I said previously, I'm happy to have to separate (external) DHCP servers on the other two VLANs. I'm away from the 2820n and won't be able to look at the configuration interface for a couple of weeks.

Thanks again for advice.

I think you need to read the manual a bit Forget the VLANs as they're confusing the issue for a minute. They're not real VLANs as you might think of, but just a way of isolating ports from each other and nothing more. The Draytek DHCP will work across all ports regardless of this setting. The 'secondary' DHCP is for when you are assigned your public WAN IPs to LAN devices, based on MAC address.

To do what you're thinking of (4 ports, 4 subnets), you'll need to use the VLAN to isolate the ports, then disable the router DHCP and use an external server on each port.

I see. My only experience is with Cisco kit so I didn't realise the VLAN situation with this router. I appreciate the comment about the 2820 DHCP servers.

I'm a great believer in RT*M but won't have access to it, or the 2820 itself for a couple of weeks!

Thank you for the clarification.

Hi. I've got similar issue. I've got 2950 but it's got the same functionality regarding VLANs. I also thought I can use second DHCP server for the second subnet isolated by port based VLAN but I read the manual and it mentions only about public IPs - like you say.

Basically I'd like to have 2 subnets.
I mean I'd like to have 1st subnet on 3 ports using 2950's DHCP server and 2nd subnet on 4th port using subnet's own DHCP server or just static IPs.

The thing is if I set up all like:

router 2950 (192.168.30.1)

P1 P2 P3 (VLAN1)
192.168.30.0/24

and

P4 (VLAN2)
192.168.20.0/24

What would be the gateway for VLAN2? Would it be gateway 192.168.30.1 - from different subnet? Will that work?

Thanks
Michael