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VLAN Setup - New to VLAN's

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Stephen Loader
Occasional Visitor

VLAN Setup - New to VLAN's

Hi

Wondering if someone could point me in the right direction to setting up vlans.

At the school I work at we have a 5308xl populated with the various modules where all our servers plug into and where all our fiber and cat6 feeds to other hp 2600 series and 2500 series switches around the school site.

Would like to setup vlans to separate out certain areas and departments.

I'm pretty confident from what i've read about vlans to setup the switches but the main worry is the routing between vlans and also the dchp request.

Will the 5308xl route between the vlans and also how do i go about setting up dhcp so that the Windows 2k3 server we have that does DHCP will give out the correct address for the correct subnets.

Any info regarding how I would go about setting this all up would be greatly appreciated as its giving me brian ache just thinking about it.


Thanks for your help in advance.
6 REPLIES
Jonathan Axford
Trusted Contributor
Solution

Re: VLAN Setup - New to VLAN's

Hi Stephen,

The 5308 will route between the VLANS no problem. Just configure it to become the Default Gateway for all of the subnets (VLANS).

Also, in each VLAN that is different to the one that the DHCP server sits on, add in the DHCP-HELPER comand.

I can't remeber the exact syntax off the top of my head, but this function listens for DHCP requests and automatically forwards them to the DHCP server.

i.e

Vlan 100
ip helper-address 10.10.10.10 1

Again, sorry i can;t remember the exact syntax but if you look it up in the 5308 config guide you will find it.

If the 5308 is to be your only Layer 3 switch (Router) you should just be able to enable IP routing and away you go.

Hope this has helped a little,

Cheers

Jonboy
Where there is a will there is a way...
Stephen Loader
Occasional Visitor

Re: VLAN Setup - New to VLAN's

cheers for the reply, thats a great help.

Do I have to do anything wierd with the setup of the DHCP server so that it knows which addresses to dole out to which VLAN etc along with the gateway info??
Jonathan Axford
Trusted Contributor

Re: VLAN Setup - New to VLAN's

All you have to do is create a scope for each VLAN. The DHCP helper command will know what Scope to assign an address from based on the default gateway that the request came in on. (If that makes sense!)

So, if you have 3 VLANs, the 5308 will be the default gateway for each of those VLANS.

Each scope will be a seperate IP range with the Default gateway set to be the Default gateway of that VLAN.

Let me know if you need any more info,

cheers
Where there is a will there is a way...
Stephen Loader
Occasional Visitor

Re: VLAN Setup - New to VLAN's

Thanks for that, i think it makes sense.
Michael Finney
Occasional Visitor

Re: VLAN Setup - New to VLAN's

Sorry for taking a step back - but how do setup a VLAN address on a Procurve 2900. It seems that you can assign a single IP address to a VLAN - but you cannot define a subnet. Basically -I've two PC's plugged into a 2900 - with static IP's on different subnets - but they will not comminicate with each other
Cheers Mikefin
Joel Belizario
Trusted Contributor

Re: VLAN Setup - New to VLAN's

Hi Mike,

When you define an IP address for a VLAN you are required to define its subnet mask as well - bear in mind when you assign an IP to a VLAN you are in essence creating a router (hence routing interface) for that VLAN.

For example, if you were to define VLAN 1's IP address as 192.168.0.1/24 that means only hosts in that address range will be able to have traffic forwarded out of that VLAN. That is provided that the default gateway of the hosts are defined as the VLAN IP address .

To answer the second part of your question, IP routing must be enabled on the switch to perform inter-VLAN routing.

Another thing to watch out for is that you have not defined any of your VLANs as a management VLAN as this will disable routing for that VLAN to prevent access from devices not on the management subnet.

Hope this helps!

Cheers
Joel