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  Asked: Jul 10 2007   2:57 PM GMT
  Asked by: drainey

Configuring VLANs


Networking, Hardware, Routers, Switches, Hubs, Cabling, Hewlett-Packard

Hello All;

If I'm configuring multiple VLANs on a Layer 3 switch (HP) do I have to setup static routes or will the switch learn them automatically?

Also if I have multiple VlAN's on the Layer 2 switches that connect to the Layer 3 do I have to setup port trunking in order for traffic to be able to pass to all VLANs?

Thanks in advance.

Dave

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Last Answered: Jul 11 2007  1:06 PM GMT  by astronomer




Dave:
If you aren't connecting to any other networks, you don't need to add routes to the layer 3 switch. Think of it as a router. If you configure an IP for each VLAN, the router will automatically know about that subnet and the VLAN associated with it. On the other hand, if you need to reach other networks not directly connected to the router, you will need to notify the router in some way. This can be with a static route statement or by using dynamic routing like RIP or OSPF.

As for the trunking, in the non-cisco world, this is referred to as VLAN tagging. You will have to configure all of the VLANS you want to pass through a switch, even if no user ports will be mapped to that VLAN.
For the port connecting the switches, one VLAN can be untagged. This is called the native VLAN in cisco language. All of the other VLANS running through the port have to be tagged. If you do this, you can run all of the VLANs to every switch so they can be brought out wherever they are needed.
Once you have configured VLANs on an HP switch, the way to map a user port to a VLAN is to set that port to use just that VLAN untagged.
The VLAN section under the switch configuration menu is fairly straightforward. Once you have created the VLANs on the switch, the VLAN port assignment section is obvious.
rt
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tbitner  |   Jul 11 2007  1:35PM GMT

Dave,

My remarks (possibly flawed); If you give you Vlan interfaces IP address, the L3 switch should know how to get to those directly connected networks. Your hosts will need their gateway changed to the vlan interface IPs. You’ll need static routes for networks not directly connected. Think of a L3 switch as a standard switch until you put IP addresses on interfaces (including virtual interfaces). Once an interface has an IP address, it behaves like a router interface. Make sure to turn on IP routing on the switch.

If you stay with L2 Vlans, you’ll need one trunk port (tagged for vlans) connected to a router that has sub-interfaces for each vlan to route between each vlan. This is called “router on a stick”.

For the L2 switches with multiple VLANS, is each switch a separate VLAN, or multiple VLANs on multiple switches? If the latter, yes you’ll need a “tagged” port to trunk all the VLANS across a single link. From my brief experience, though, I could not use more than one port a trunked on a HP switch.

Also try looking in the HP procurve guides online, they’ll explain how HP implements VLANS.

 

AmyKucharik  |   Mar 3 2008  4:54PM GMT

Hi Dave,
This may or may not help with your specific question, but I thought it might be good as a general reference:
Screencast: Configuring VLANs

It’s a 15-minute automated demo of how to configure a VLAN with David Davis. Enjoy!