int vlan up while no port connected on the vlan

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May 19th, 2006
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Having a cat3750 stack (Layer2-Layer3, release 12.2.25SEB4), I would like to have an interface vlan up for administration reason with no port connected on this vlan?

Do you know a way to get it, wihout using loopback interface, i.e. having a switch port stat up while not beeing connected. (no keepalive nor L3 interface with no keepalive do not help me)

sh run int fas 3/0/24

Building configuration...

Current configuration : 170 bytes


interface FastEthernet3/0/24

no switchport

no ip address

no logging event link-status

no keepalive

no snmp trap link-status

power inline never

no mdix auto


sh run int vlan 1

Building configuration...

Current configuration : 96 bytes


interface Vlan1

description *** Management ***

ip address a.b.c.d


sh int vlan 1

Vlan1 is up, line protocol is down

sh int fast 3/0/24

FastEthernet3/0/24 is down, line protocol is down (notconnect)


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glen.grant Fri, 05/19/2006 - 05:39
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No way that i know of . If you don't have a link up that contains that vlan why would the SVI need to be up ?? How would you get to the SVI if you don't have an active port in that vlan ??? Maybe you can elaborate on what you are trying to do ??

jabouaf Fri, 05/19/2006 - 06:16
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Hello Glen,

Thank you replying so fast.

Here is some more information:

The switch is used as a router too.

It is reachable by a WAN router connected to this switch on an another vlan (vlan 9). The SVI for the management of this switch is on a dedicated vlan (vlan 1) but this is the only switch of this site.

The management of this switch isn't in the same vlan as the router.

And I wonder if there is a way to have a SVI up just for the management process of this switch, without using a loopback interface.

WAN router is on vlan 9 and I would like to have the switch management IP'address on vlan 1.

Vlan 1 IP network is a subnet of the network routed by the WAN router (managed by an operator).


ankurbhasin Fri, 05/19/2006 - 06:52
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Hi Friend,

Why don't you use int vlan 9 only for management purpose.

I don't think there is any way which can bring the layer 3 interface up without connecting anything physically to this port.

Or else why don't you connect a hub or any dummy pc to vlan 1 to bring it up?



jabouaf Fri, 05/19/2006 - 07:24
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Hello Glen,

I found that the "autostate" function seems to no work on such switches.



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