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two switchs

This may be a simple question, but I will ask my question so I can clear up, a few things in my head.

I have a 2900 XL I created a vlan so that port 0/3 will use vlan2. Then I plugged in a switch using a standard Cat5 cable. The light come up on both the switchs and it looks like every thing is working fine, so I plugged my Workstation into the switch which was connected up to 0/3 (Vlan2) using the new IP address.

From the WS is was unable to ping the IP address of the Vlan2 (IP address is So I checked to see if the vlan2 was on and I got this information

VLAN2 is administratively down, line protocol is down.

I just remembered that I should use a cross over cable to connect both of the switchs.

Also all the lights on both switchs are flash when I plug the second switch into 0/3. Is this because I am using a stright cable and not a cross over.

I just want to know if I am right about the cross over cable being the problem. Also does my set up sound right.

Thanks alots


Re: two switchs

Crossover cable is not the problem; if you got a link between the two switches using a straight-through cable then one or both has the ability to do auto-crossover. I don't think Cisco's 2900XL can do this; I do know that some of the recent 3Com switches can. What is your other switch?

If the second switch was not capable of doing auto-crossover, then using a straight-through patch cable should get you NO link at all. This is when you would want to use a crossover cable.

If VLAN2 is listed as administratively down, that means the "interface VLAN2" is in a "shutdown" state. VLAN interfaces on a 2900XL switch are for management purposes only; you can have as many defined as you want, but the switch can only be managed from one active VLAN interface, which in your case is probably still VLAN1.

The 2900XL is NOT a Layer 3 switch, so it will not support more than one active IP address at a time.

If you want it manageable from the VLAN2 interface's IP address, you will need to use a serial cable to connect to the console port, go into enable mode, and run the following:

config term

interface VLAN1


interface VLAN2

no shutdown


copy running startup

This will shutdown your VLAN1 interface, activate your VLAN2 interface, and save your configuration changes. If you try to do this from a Telnet session, as soon as you shutdown the VLAN1 interface you will lose your Telnet session. Only way to get it back would be to reboot the switch (since the config wasn't saved at that point, VLAN1 will come back up after reboot) or use the console cable connection to finish the config instructions above.

Hope this helps.

Community Member

Re: two switchs

Thanks for the reply, the second switch is some cheap one name unknown.

By reading your post, I will not be able to have two vlans running at the same time. I can only use the vlans has management purposes on my switch what do you mean by this ?

So I will be unable to do what I planned to do.

Thanks again


Re: two switchs

You can run two VLANs at the same time. You just can't manage the switch using two different IPs associated with two different VLANs. You have to pick only one IP for management (unless you move to a Layer 3 switch like the 3550, in which case you can have as many IPs as you want, one per VLAN).

Once you create two VLANs, devices on one VLAN will not be able to communicate with devices on the other. However, devices on one VLAN will be able to communicate with other devices on the same VLAN.

You need a Layer 3 device such as a router or Layer 3 switch that connects to each of the VLANs, in order to facilitate communications between VLANs. There are a variety of different ways you can connect these devices to your Layer 2 VLANs.

As far as what I meant by using only one VLAN on the switch for management purposes, when you Telnet the switch, you supply your Telnet application with an IP address as the destination you're trying to reach. That IP address is the one that is active on the switch.

If you're on the same VLAN as the management interface of the switch, your Telnet session will take place directly between your computer and the switch.

If you're on a different VLAN from the one that the switch's management interface is set for, your Telnet session will go to your default gateway first (the router or Layer 3 switch mentioned earlier), and then from there to the switch.

If you don't have a router or Layer 3 switch connecting the two VLANs, you won't get through.

A couple of special cases where you could: a computer with two network adapters, on connected to each VLAN. This is called dual-homing or multihoming. Or a high-end server network adapter that has the ability to send and receive VLAN tag information on a switch VLAN trunk connection. (The single adapter acts as multiple virtual adapters.)

On some operating systems, you can even turn on routing so that your computer can act as the default gateway between the two VLANs. You then have to configure the other computers on each VLAN to use that computer as their default gateway.

What are you trying to do, anyway?

Community Member

Re: two switchs

Thank you very much konigl.

I am new to cisco so every thing is coming in place one step at a time.

I now understand why it did not work, is it because my switch does not support ISL.

I was planning to create a DMZ so my servers would be in one vlan and all my workstation in other vlan.

So to get the result I want I will need to get a layer 3 router or switch.

I think I will make a router based on my old P166 running Linux. I think it will be alot cheaper.

Thanks you once again you really made me understand the problem.

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