2950 switch vlan

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Oct 15th, 2007
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I have a 2950 switch. As I found I can create lots of vlans, but only one can be up. Why? What is the benefit of this?

(When I create more than one others are in state "administratively down".)


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Collin Clark Mon, 10/15/2007 - 05:25
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The 2950 switch is a layer 2 only switch. It can only have one IP address, which is used for management purposes. If you need to route between VLANs on a switch, you need a switch that can support a layer 3 image.


HTH and please rate.

Richard Burts Mon, 10/15/2007 - 07:54
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Norbert


It is a subtle point but it is important to understand the difference between having multiple VLANs on the switch and having multiple VLAN interfaces on the switch.The 2950 is a layer 2 switch and as such it does support having multiple VLANs. You can define multiple VLANs and can assign ports/interfaces to multiple VLANs, and can forward at layer 2 among the multiple VLANs. On a layer 2 switch you can have only a single VLAN interface. The VLAN interface is a layer 3 entity (where the VLAN is a layer 2 entity). On the layer 3 switch the layer 3 VLAN interface is used for management purposes. Having a VLAN interface or not having a VLAN interface does not impact the switch forwarding at layer 2. Having the layer 3 VLAN interface gives us the ability to access the switch remotely and to manage the switch.


If it were a layer 3 switch instead of a layer 2 switch it would support multiple VLAN interfaces. But a layer 2 switch can have only a single active VLAN interface.


HTH


Rick

guruprasadr Tue, 10/16/2007 - 01:25
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HI,


I would like to add more on this.


In 2950 Switch by default Management VLAN used for administrative purpose will be in UP state to access teh Switch.


Neverthless if you could create multiple VLANs means the it can do only L2 capability also the VLAN will be Up only if some device is connected to each VLAN ports.


DO RATE ALL HELPFUL POSTS.



Best Regards,


Guru Prasad R

professzor Tue, 10/16/2007 - 01:25
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Thank you very much for detailed answer.

I'm getting understood it.

Maybe stupid question, but, in the long 2950 manual I have found the vlan interface creating command then. What is the command for creating multiple vlan, not for multiple vlan interfaces?



ankbhasi Tue, 10/16/2007 - 03:18
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Hi Friend,


Are you asking how can you create multiple vlans at layer 2 and not vlan interfaces correct?


If yes then you can go to vlan database mode and create multiple vlans somehting like this


Switch#vlan database

Switch(vlan)#vlan


And you can follow the same command "vlan " to create multiple layer 2 vlans.


Please come back if you have any doubts.


HTH


Ankur


*Pls rate all helpfull post

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