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Webcast-Catalyst9k
New Member

Vlan2 shuts down when bringing up Vlan3

Hi, I just want to create 2 vlans. Vlan2 and vlan3. I have created them and they are in the database but when I try and bring up one, the other goes admistratively down and vice versa. Anyone have a idea of what I am doing wrong?

11 REPLIES
New Member

Re: Vlan2 shuts down when bringing up Vlan3

Here is the attachment

New Member

Re: Vlan2 shuts down when bringing up Vlan3

Its a 2950 switch and doesn't support EMI for l3 functionality and therefore only supports 1 SVI active at a time.

New Member

Re: Vlan2 shuts down when bringing up Vlan3

I am confused. I know the 2950 is not a layer three device. I am plugged into an ASA and uplinked on port fa0/24 between switch and ASA. Doesn't the ASA know how to do router on a stick? See Visio attachement please.

New Member

Re: Vlan2 shuts down when bringing up Vlan3

I just got it - thanks!

New Member

Re: Vlan2 shuts down when bringing up Vlan3

No I don't got it. If I remove the IP from vlan3 (see original attachment) or remove the vlan 3 interface will it work?

New Member

Re: Vlan2 shuts down when bringing up Vlan3

There is no way to have an IP address per vlan on the switch?

New Member

Re: Vlan2 shuts down when bringing up Vlan3

I got it l2 vs. l3 - TOTAL brain fart. It HAS been a while ;) thanks!

New Member

Re: Vlan2 shuts down when bringing up Vlan3

Check the TAC case collection, I see a issue that you have with its resolution.

Hall of Fame Super Gold

Re: Vlan2 shuts down when bringing up Vlan3

The 2950, like the 2900/3500XL, will only support ONE (1) VLAN up/up.

Hall of Fame Super Gold

Re: Vlan2 shuts down when bringing up Vlan3

Jerry

There is an aspect to consider that may help to clarify your issue. There is a difference between a VLAN and a VLAN interface. There is a major difference between creating 2 VLANs and creating 2 VLAN interfaces. On the 2950 you certainly can create multiple VLANs (have multiple VLANs in the database) and assign different ports to different VLANs, and trunk multiple VLANs to other devices over trunk ports. This is quite different from creating VLAN interfaces. You can create VLANs without creating VLAN interfaces. Creating a VLAN interface is creating a layer 3 interface. And on layer 2 switches like the 2950 there can be only a single active VLAN interface at a time.

So on switches like the 2950 it is easy to create multiple VLANs but you can have only a single active VLAN interface.

HTH

Rick

New Member

Re: Vlan2 shuts down when bringing up Vlan3

Rick and everyone thanks!. This clarifies a lot. After pounding on it for a while I cam to the same conclusion.

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