VLAN question ( Help pretty please )

Zaits

Hello,

My task is to setup VLAN23 on port fa0/8 and then configure the port going to the router (Fa0/12) for trunking. My problem is everytime I issue the command no shutdown for the vlan I create it shuts down vlan 1( the default). I am using a Cisco Catayst 2950 ios 12.2. My next question which may or may not be related to this problem is when I tried to trunk the interface ( Fa0/12) that seemed to work fine but then I tried to issue the command encap dot1q. The response I got back was not recongized ?? I am confused why it does not recongized the encapsulation command...

Any advice would be a great help

remyforbes777

You do not need to do a no shut on vlan23. If you do a no shut you are telling the switch that you want vlan23 to become your management vlan which is by default vlan1. You can have only one management vlan active at a time.
For your second question when you are trunking are you issuing the command switchport mode trunk on the interface and then the encapsulation command?

EdTheLad

The 2950 will only allow one SVI i.e. switched virtual interface to be up at any one time, this is why when you do a "not shut" on interface vlan 23, "interface vlan 1" is shutdown automatically.The main question is why you are playing with "interface vlan 23" , to create vlan 23 and apply vlan 23 to an interface you do not need to have the SVI up, this SVI is for router management only, remember this switch is layer 2 so you are no working with ip addresses.

The 2950 supports dot1q only, since there is no other encapsulation type possible you dont have an option to configure the encapsulation.

remyforbes777

The 2950 supports dot1q only, since there is no other encapsulation type possible you dont have an option to configure the encapsulation.


Ed the Lad is absolutely correct. Forgot about that. Good call Ed.

tech-airman

Zaits wrote:

Hello,

My task is to setup VLAN23 on port fa0/8 and then configure the port going to the router (Fa0/12) for trunking. My problem is everytime I issue the command no shutdown for the vlan I create it shuts down vlan 1( the default). I am using a Cisco Catayst 2950 ios 12.2. My next question which may or may not be related to this problem is when I tried to trunk the interface ( Fa0/12) that seemed to work fine but then I tried to issue the command encap dot1q. The response I got back was not recongized ?? I am confused why it does not recongized the encapsulation command...

Any advice would be a great help

Zaits,

Which exact IOS version are you using? Type "#show version" and include the parenthesis, numbers, and letters following "12.2"

Zaits

EdTheLad wrote:

The 2950 will only allow one SVI i.e. switched virtual interface to be up at any one time, this is why when you do a "not shut" on interface vlan 23, "interface vlan 1" is shutdown automatically.The main question is why you are playing with "interface vlan 23" , to create vlan 23 and apply vlan 23 to an interface you do not need to have the SVI up, this SVI is for router management only, remember this switch is layer 2 so you are no working with ip addresses.

The 2950 supports dot1q only, since there is no other encapsulation type possible you dont have an option to configure the encapsulation.

Thanks alot for clarify this it makes perfect sense now why I am seeing the vlan 1 shutdown when I do a no shut command on vlan 23.

The reason why I am configuring the interface vlan 23 is because I am trying to setup a 192.168.23.x /24 scheme for that vlan. I want a different ip scheme for my default (vlan 1) 172.20.x.x. I guess its just my inexperience but I was under the assumption you needed to assign the ip address to the vlan using the int vlan id command.

Thanks again everyone for your responses and this proves once again why I love this site so much.

remyforbes777

You can assign an IP address to that vlan but its just for management purposes. You can use that vlan for any subnet though. For example you can assign an IP to vlan 23 like so:
interface vlan 23
ip address x.x.x.x x.x.x.x

understand that that ip address is only for vlan management and can only be used if that vlan is brought to a status of up/up. Once you do this any other vlans will be shut down for management purposes but your vlans themselves won't be shut down. Traffic will still flow. Now just because you assign that vlan 172.16.x.x ip address you can use 192.168.x.x ip address scheme on that vlan.