Problem with Inter V-Lan routing might be due to STP

[aamirshafiq]

Hi!

Please have a look at the attached pictures, till yesterday everything was working but today inter v-lan routing is not working, I am unable to get the IP addresses from the central switch. Central switch attached with 3 different L2 switches. There is no loop according to my understanding. Please help

[jabritt]

Hi,

Sorry to hear your having problems! Can you provide any more detail about your configuration?

Interfaces, topology, would be helpful. Was this working before? Has anything been changed if it was?

Also, here is some Cisco documentation on interVLAN Routing.

http://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html#maintask1

[aamirshafiq]

Hi!

Problem solved after restarting the switch. It was showing my vlans status down. I don't know exactly what happened. Is there any way to bring the vlans up again without restarting?

[Aleksandra Dargiel]

Hi Aamir,

VLAN would show down in the following scenarios:

1. VLAN interface was administratively down - this way you can prevent intervlan routing (as you noticed) and must be not saved in satrtup config

2. last port belonging to this VLAN is down - that could be actually your scenario when STP blocked ports gi26 and gi27

Now the question is why would STP block those ports? what is connected on those ports? Cisco Catalyst?

Regards,

Aleksandra