Vlans not working after power outage

[zzbronski]

I have a very odd problem. We had a power outage yesterday and some of the switchgear went down after the UPS ran out of battery power. When the power came back on, none of the computers were getting dhcp addresses. However, every switch was online and on the network, wan/man circuits up and able to connect into the switches/routers from outside. All the configs look normal and correct. All the IP phones are working properly and have IP addresses from the voice dhcp scopes. The dhcp server is fine and is working properly and the scopes are not full. There are no data IP addresses held by IP phones. PCs connected to three of the switches/vlans are not getting dhcp for them. When I change the vlan assignment on the ports to one of the other vlans that is working then it gets an IP. Switching back to the original vlan does not work. I cannot figure out what is wrong. I am very frustrated and would like some input from somebody on possible solutions.

[Reza Sharifi]

if you are using the access switches as a layer-2 devices, do the vlans exist in theses devices "sh vlan id xx"

are the vlans are added to the trunk?

if you have distro/core switch for the SVI.

Is the SVI in up and up mode for these vlans?

if all of the above are correct

you may want to clear the arp for these vlans on the layer-3 switches/routers

also you may want to clear the mac address table on layer-2 switches and test again

HTH

Reza

[zzbronski]

I am running two cores for layer 3 with the vlans defined evenly.The client switches are layer 2 and do not have the vlans configured on them. Using spanning-tree and vtp to distribute the vlan traffic accross dot1q trunks that connect all the client switches to the core switches. All vlan interfaces are up up on the cores. I cleared the arp on both cores for the vlans that arent working and cleared the mac address-table on the client switches for the same vlans. Still not working. I am at a loss as to what to look at next.

[Peter Paluch · Accepted solution]

Hello,

Just a quick shot: are you using VTP Pruning? If yes, can you try deactivating it?

Best regards,

Peter

[milan.kulik]

Hi,

a) Are ip helper-addresses  configured correctly on the SVIs in theose 3 VLANs not working properly?

b) When you assign an IP address to a client in that VLANs manually, are you able to Ping the DHCP server?

HTH,

Milan