Unable to Statically or Automatically Assign IP for a VLAN

[NoelAdams7444]

Hi guys,

Not too sure if I have posted on the correct but I have 3 switch stacks, 1 on each floor which are connected via Layer 3 Ether Channels. I have created a VLAN 240 for our guest Wi-Fi which I have extended on all switch stacks via Access ports for now.

The 240 Vlan is directly connected to the 3rd switch stack with an IP of 10.100.240.1 and then added on the other two.

The 240 VLAN gets DHCP from our SonicWall which is directly connected to our 3rd switch stack on a 253 network.

Now when I connect to the 240 guest network on the 3rd and 2nd switch stack I can receive an IP and get on the network. However when I connect to the 1st switch stack I can not. I am not sure why this is as the Vlan is setup the exact same way on the 2nd switch stack.

When creating an untagged 240 port and plugging my laptop directly into the 1st floor stack I do not receive an IP. Statically assigning a 240 IP also fails and I am unable to ping the the 240 Vlan interface when configured.

Do you guys have any ideas where the issue can be? I'm pretty sure it can't be the Vlan as it is up on all switches but then again I'm not too sure now. Also all switches have a route to the 253 network which the firewall is on. If you need any more information I can provide it. Thanks.

[kubn2]

Hi, 

Did you checked with sh vlan brief on the 1st stack to make sure vlan is visible and assigned to correct interface?

Did you checked STP on all of the switches?

Also can you paste relevant configuration parts from 2nd and 1st stack?

[NoelAdams7444]

Hi,

I have checked the 240 Vlan on 1st stack and it appears to be active. The correct port Gi3/0/31 which is linking to the 3rd stack is assigned to that 240 Vlan.

I have checked STP on all the switches for Vlan 240. The 2nd stack link port is the root and then on the 1st and 3rd switch stack ports they're designated. I have provided a screen shot of these outputs.

I have attached screen shots showing the Vlan interface created on the 3rd stack. I have also attached screen shots of a Vlan brief on all switch stacks of which I have highlighted the ports linking the switches.

I hope this helps.

[NoelAdams7444]

Hi all,

I was having a look at the STP summary and was wondering if the current setup could possibly be causing the issue.

As per the attached screen shots.

3rd Stack is the root bridge
2nd Stack has the root port
1st Stack also states it is the root bridge

They all have default priorities so should elect the root bridge via lowest MAC which in this case should be 1st Stack. However the main thing is that the root ID is also different on the 1st Stack oppose to the other two which are working fine.

Now I may just be reading too much into it but could this be causing an issue with being unable to assign 240 IP addresses on the 1st Stack?

[NoelAdams7444]

Does anyone have any ideas? I would really appreciate it.

I have put together a STP topology of Vlan 240 and to also illustrate the connections between the switches.

At this stage I'd like to know if this could possibly be causing an issue with being unable to assign 240 IP addresses on the 1st Stack.

[Richard Burts]

Would you post the output of show interface status and of show interface trunk. Also please identify the port where you are connected.

[NoelAdams7444]

I have attached the interface status of the port connecting 1st to 3rd Stack. The attachments highlights the connected ports. I have also attached interface trunk for those stacks. Bear in mind these switches are currently connected as access ports. Thanks.