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L3 VLAN showing up but no physical interface bound or physical interface down.

 

 

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drew.weaver at thenap

Jan 22, 2008, 6:21 AM

Post #1 of 5 (920 views)
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L3 VLAN showing up but no physical interface bound or physical interface down.

Hi there. We have seen this issue on two separate Catalyst 6500s in the past two weeks or so, we've noticed that on occasion either with a Layer 3 VLAN with no FastEthernet/GigabitEthernet port attached to it, or with one attached to it which is either down or administratively shutdown that the Layer 3 VLAN refuses to notice that it should in fact "give it a rest" as they say. Has anyone seen anything similar to this in the past. We aren't running VTP or any multi-switch/campus wide VLANs. All of our VLANs are contained intra-switch. Both switches are running the same version of code. The only remedy we've found for solving this issue is to simply blow away the VLAN (which is usually what we're trying to do when we notice this anyway), but we are a little concerned by what could be the cause.

Thanks.
-Drew

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markom at vodafone

Jan 22, 2008, 6:22 AM

Post #2 of 5 (877 views)
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Re: L3 VLAN showing up but no physical interface bound or physical interface down. [In reply to]

If I'm not much mistaken, VLAN will be up if you have any trunks that "contain" it up. Are you sure that you are not running unliminted trunks on the switch, causing SVI to be up?


-----Original Message-----
From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-bounces [at] puck] On Behalf Of Drew Weaver
Sent: 22. janúar 2008 14:27
To: cisco-nsp [at] puck
Subject: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


Hi there. We have seen this issue on two separate Catalyst 6500s in the past two weeks or so, we've noticed that on occasion either with a Layer 3 VLAN with no FastEthernet/GigabitEthernet port attached to it, or with one attached to it which is either down or administratively shutdown that the Layer 3 VLAN refuses to notice that it should in fact "give it a rest" as they say. Has anyone seen anything similar to this in the past. We aren't running VTP or any multi-switch/campus wide VLANs. All of our VLANs are contained intra-switch. Both switches are running the same version of code. The only remedy we've found for solving this issue is to simply blow away the VLAN (which is usually what we're trying to do when we notice this anyway), but we are a little concerned by what could be the cause.

Thanks.
-Drew

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jason.plank at comcast

Jan 22, 2008, 6:31 AM

Post #3 of 5 (882 views)
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Re: L3 VLAN showing up but no physical interface bound or physical interface down. [In reply to]

Drew,

Did you look at spanning-tree and confirm that the vlan was no longer in spanning-tree? The switch will not turn the vlan interface down if the vlan is still in use in spanning-tree.

--
Regards,

Jason Plank
CCIE #16560
e: jason.plank [at] comcast

-------------- Original message ----------------------
From: Drew Weaver <drew.weaver [at] thenap>
> Hi there. We have seen this issue on two separate Catalyst 6500s
> in the past two weeks or so, we've noticed that on occasion either with a Layer
> 3 VLAN with no FastEthernet/GigabitEthernet port attached to it, or with one
> attached to it which is either down or administratively shutdown that the Layer
> 3 VLAN refuses to notice that it should in fact "give it a rest" as they say.
> Has anyone seen anything similar to this in the past. We aren't running VTP or
> any multi-switch/campus wide VLANs. All of our VLANs are contained intra-switch.
> Both switches are running the same version of code. The only remedy we've found
> for solving this issue is to simply blow away the VLAN (which is usually what
> we're trying to do when we notice this anyway), but we are a little concerned by
> what could be the cause.
>
> Thanks.
> -Drew
>
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/

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markom at vodafone

Jan 22, 2008, 6:32 AM

Post #4 of 5 (894 views)
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Re: L3 VLAN showing up but no physical interface bound or physical interface down. [In reply to]

Could you verify absence of negotiated trunks by running "show int trunk"? It is sometimes easy to miss trunks that should have not been trunks...

-----Original Message-----
From: Drew Weaver [mailto:drew.weaver [at] thenap]
Sent: 22. janúar 2008 14:41
To: Marko Milivojevic; cisco-nsp [at] puck
Subject: RE: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


I apologize I should've clarified that we aren't doing any kind of trunking. Pretty much all of the VLANs we're doing are very simple switchport, switchport access vlan x type VLAN/interface configurations.

Thanks,
-Drew

-----Original Message-----
From: Marko Milivojevic [mailto:markom [at] vodafone]
Sent: Tuesday, January 22, 2008 9:23 AM
To: Drew Weaver; cisco-nsp [at] puck
Subject: RE: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


If I'm not much mistaken, VLAN will be up if you have any trunks that "contain" it up. Are you sure that you are not running unliminted trunks on the switch, causing SVI to be up?


-----Original Message-----
From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-bounces [at] puck] On Behalf Of Drew Weaver
Sent: 22. janúar 2008 14:27
To: cisco-nsp [at] puck
Subject: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


Hi there. We have seen this issue on two separate Catalyst 6500s in the past two weeks or so, we've noticed that on occasion either with a Layer 3 VLAN with no FastEthernet/GigabitEthernet port attached to it, or with one attached to it which is either down or administratively shutdown that the Layer 3 VLAN refuses to notice that it should in fact "give it a rest" as they say. Has anyone seen anything similar to this in the past. We aren't running VTP or any multi-switch/campus wide VLANs. All of our VLANs are contained intra-switch. Both switches are running the same version of code. The only remedy we've found for solving this issue is to simply blow away the VLAN (which is usually what we're trying to do when we notice this anyway), but we are a little concerned by what could be the cause.

Thanks.
-Drew

_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/
_______________________________________________
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drew.weaver at thenap

Jan 22, 2008, 6:40 AM

Post #5 of 5 (915 views)
Permalink
Re: L3 VLAN showing up but no physical interface bound or physical interface down. [In reply to]

I apologize I should've clarified that we aren't doing any kind of trunking. Pretty much all of the VLANs we're doing are very simple switchport, switchport access vlan x type VLAN/interface configurations.

Thanks,
-Drew

-----Original Message-----
From: Marko Milivojevic [mailto:markom [at] vodafone]
Sent: Tuesday, January 22, 2008 9:23 AM
To: Drew Weaver; cisco-nsp [at] puck
Subject: RE: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


If I'm not much mistaken, VLAN will be up if you have any trunks that "contain" it up. Are you sure that you are not running unliminted trunks on the switch, causing SVI to be up?


-----Original Message-----
From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-bounces [at] puck] On Behalf Of Drew Weaver
Sent: 22. janúar 2008 14:27
To: cisco-nsp [at] puck
Subject: [c-nsp] L3 VLAN showing up but no physical interface bound or physical interface down.


Hi there. We have seen this issue on two separate Catalyst 6500s in the past two weeks or so, we've noticed that on occasion either with a Layer 3 VLAN with no FastEthernet/GigabitEthernet port attached to it, or with one attached to it which is either down or administratively shutdown that the Layer 3 VLAN refuses to notice that it should in fact "give it a rest" as they say. Has anyone seen anything similar to this in the past. We aren't running VTP or any multi-switch/campus wide VLANs. All of our VLANs are contained intra-switch. Both switches are running the same version of code. The only remedy we've found for solving this issue is to simply blow away the VLAN (which is usually what we're trying to do when we notice this anyway), but we are a little concerned by what could be the cause.

Thanks.
-Drew

_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/
_______________________________________________
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