VLAN Advice

hybrid · 18 Jun 2006 at 18:52

Not sure how many people here have much exprience with VLANs but here goes...

Basically we have a network which we need to be split into 3 seperate VLANs. Is it best to give each network a totally different IP range and subnet, or keep the subnets the same? From time to time traffic will need to access different VLANs to retrieve data from another server.

We have layer 3 switches (HP 5308XL's) so im hoping this can safely route the traffic between the networks.

Any help would be great.

hybrid · 18 Jun 2006 at 19:30

Thats the way i was going to start doing them. But then reading on the HP website on one of the PDFs it states...

name "VLAN100"
ip address 10.10.100.1 255.255.255.0

name "VLAN200"
ip address 10.10.200.1 255.255.255.0

Seems like in that example they have them both on the same subnet too.

Confusing that part. :S

hybrid · 19 Jun 2006 at 18:06

1. Well on one VLAN we will have roughly ~340 machines.
2. On the other we have 20 for admin use.
3. Then another for a wireless DMZ.

At present they are all using the same DHCP server so we hope to seperate these so all 3 VLANs have their own independent DHCP servers.

The IP Structure at the moment is using the 172.16.0.x range and the subnet of 255.255.0.0.

What would be the best IP structures for all seperate VLANs?

hybrid · 19 Jun 2006 at 20:28

VLAN1 is going to have more than 254 hosts though. It should be alright to use 172.16.1.x/22 for this one wouldnt it?

I'd rather keep this so we have a nice amount of room for expansion.

But would it work?

Also, we were thinking about giving each VLAN a different IP range altogether to distinguish the networks easily from each other. Would this cause any problems even if they were on totally different ranges and subnets?

Yes i know this is the deep end but any help is mostly appreciated.

hybrid · 19 Jun 2006 at 21:57

Yup thats not a problem.

Thanks very much for the help Rich.

The way I am wanting to do it with different IP ranges and subnets would this make inter-vlans more difficult to setup at all?

So for example...
VLAN1 = 172.16.1.x/22
VLAN2 = 172.16.4.x/24
VLAN3 = 10.0.0.x/23

There will be quite a bit inter-vlan communication between VLAN1 and VLAN2.

Layer 3 routing in our switches should be able to handle those inter-vlans configs fine shouldnt it?