URGENT!!! 3560 VLAN routing question...

Unanswered Question
Jun 26th, 2008

Hi all,

I have been implementing a new Cisco 3560 this morning. The switch is setup using OSPF and connectd to a Cisco 3550 over a VLAN interface.

My question is - i have 12 other VLANs and VLAN interfaces on the switch. None of these come 'up' unless there is an active device in the VLAN. Is this correct? I usually configure one VLAN as a management VLAN and assign that an IP address, but i can't even get to that unless i put a device in the VLAN.

The 3560 itself can see all other routes in the network when i do Show Ip Route OSPF, and the OSPF adjacency is fine, but i cannot get back to any of the VLAN interfaces on the switch unless i plug a device into each VLAN...

Any help much appreciated, can post configs if this helps,



I have this problem too.
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Nagendra Kumar ... Thu, 06/26/2008 - 23:55

Hi Jonathan,

AFAIK, This is expected. You need to have atleast one active interface configured to be part of this vlan in order to get the vlan interface (SVI) up.

Alternately, IF you have any trunk interface configured and up, all SVIs will be up.

Is there any specific reason (like testing purpose) why you need reachability for a vlan which doesnt have any active device?.



jonathanaxford Fri, 06/27/2008 - 00:02


Thanks for the response. We are currently testing at the moment, so would be handy to see them all. We also like to have a management VLAn, in this case VLAN 12, that is always available for monitoring etc.

The link connecting back to the main site is a trunk link:

interface FastEthernet0/48

description Connection to NP LES 100

switchport trunk encapsulation dot1q

switchport trunk native vlan 34

switchport trunk allowed vlan 10,11,34,999

switchport mode trunk

speed 100

duplex full

srr-queue bandwidth share 1 70 25 5

srr-queue bandwidth shape 3 0 0 0

priority-queue out

mls qos trust dscp

VLAN 34 is our OSPF vlan, and i thought that by having this, all other VLAN inerfaces would come up. The trunked link is up, as we can ping over the VLAN 34 interfaces. THe switchport allowed VLAN statement only allows the OSPF VLAN and a couple of other specialist vlans across, but that is how it shoudl be as far as i know...



Nagendra Kumar ... Fri, 06/27/2008 - 01:53

" switchport trunk allowed vlan 10,11,34,999 "

In your config, vlan 12 is not in allowed vlan list of your trunk. As you dont have any other interface configured to be part of vlan 12 and your trunk doesnt have this vlan in allowed list, it is expected that the SVI will not be up.

Having either of the above will bring the SVI up.



jonathanaxford Fri, 06/27/2008 - 06:40

Thanks very much. We have placed a switch behind this one with a trunked link allowing all VLANs in, this has brought all of the SVI's up, so we are all sorted there.. just got to get the phones working now!



RandyGates Fri, 06/27/2008 - 07:34

Have you setup VTP on these devices


vlan database


vtp domain yourdomainname


vtp domain yourpassword


vtp domain server or client




Have you implemented this management?


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