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Int VLAN 10, no IP Address

Dear Members,

1/ interface vlan 10

no ip address

(VLAN 10 is in use. Would the no ip address command affect the VLAN 10, IP operations?)

2/ interface vlan 1

no ip address

(VLAN 1 is not used. But not shut down as can be seen. Is there any effect in operations?)

Thank you

Prashanth Krishnappa
Cisco Employee

Any traffic within VLAN 1 or VLAN 10 will work fine. You will need to assign an IP address to the virtual VLAN interfaces only to route between VLANs(if the switch is capable of doing routing).

However, you might want to assign an IP address to a VLAN interface for management purpose(ping/telnet, etc)

My Qusetion 1/

If vlan10 is not defined with ip address it will work fine in layer2. If vlan10 is defined with ip address it will work fine layer3. Whai will happen if vlan is defined with "no ip address"?

My question2/

I do not want to use VLAN1. I want to use another vlan for management. But as you can see, vlan1 is not shut. What effects this has?

1. This will be fine. The switch will continue to work at layer 2 for that VLAN, but the router will not route that VLAN.

2. That should also be OK. VLAN 1 will still exist. Effectively, VLAN always exists - CDP and other control protocols use it. Just in this case it will not be routable in or out.

Kevin Dorrell



The no IP address command stops the switch resources being used to support layer three activites on the VLAN. Layer two is unaffected by this.

No IP address on VLAN 1 on 3500 series is used to reduce the CPU utilization below 40%. Without this command in place on some switches it will run at 50% CPU utilization or greater.

no IP address on VLAN 10 will stop IP resources being used to support layer 3 activity on this VLAN.