Unanswered Question
Apr 3rd, 2008

I had created a sub vlan and deleted the Vlan.But still when iam giving "sh ip int brief" it still showing.ow to remove it permanently ?

Vlan5 x.x.x.x YES NVRAM up up

Vlan5.1 unassigned YES unset deleted down


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Giuseppe Larosa Thu, 04/03/2008 - 08:04

Hello nasheer,

if you can reload the switch it will solve it.

Actually, when we issue a no interface x in IOS the interface is not totally destroyed and if you issue again interface x you can retrieve the interface and its configuration.

I had a similar problem in the past while performing tests on MPLS traffic engineering: we were able to fill the IDB (interface descriptor database) and to free it we had to reload the router.

Also IOS deleted interfaces still appear in an SNMP query as a further proof that a deleted interface is not totally erased.

May I ask you what was the use of a subinterface of an SVI Vlan interface ?

Hope to help


Richard Burts Thu, 04/03/2008 - 08:08


If you have deleted the subinterface then it no longer shows up in show run. But it will continue to show up in the show ip interface brief since the original creation of the subinterface created an entry in the dynamic data structure used by running config and its associated IDB. That entry will remain in the data structure until you reload the router. So the only reliable way to get the subinterface to not show up in show ip interface brief will be to reload the router.



nasheer.ahmad Thu, 04/03/2008 - 08:24


I just tested to create a sub vlan under main Vlan which is /24 and tried to give a separate subnet .will it works ?


Giuseppe Larosa Thu, 04/03/2008 - 08:33

Hello Nasheer,

a secondary ip address could do that job for you.

I'm worried only at the fowarding plane level: when we have 802.1Q subinterface on a router we can distinguish it by its vlan id.

In this case you are using an SVI that is tied to broadcast domain layer2 Vlan5 and you create a subinterface of it: there isn't an easy to read parameter that tells what packets are for VLan5 and what are for vlan5.1.

But I suppose it can work.

best regards



This Discussion