Daisy chaining CE520s together.

glengardener · ‎05-01-2010

Hi,

I apologize if this is the wrong area to ask this question.

Background: I currently have a UC520 connected to 4 8-port CE520, with each CE520 switch on a different port. Each of these switches are in differnt locations in my office. Everything works no issues.

Problem : I recently had to move one of the switches to be in the same location as another one, however due to wiring constraint i was hoping to daisy chain the new switch off the existing switch. However everytime i plug the switch into the existing switch it errors and disables the port.

The error i am getting is

This port is disabled because an unexpected Bridge Protocol Data Unit (BPDU) is received from the connected device.

I am still a little new with regards to networking, I have tried changing the port speed, port types and using crossover cables but nothing seems to work. I have to keep resetting both devices to allow the ports to be enabled. I have also tried using the WAN port rather than the LAN port, but it seems that the moment the new switch see the network the old switch shuts the port down.

Can someone confirm whether it is possible to connect two ce520s together or whether i am doing it incorrectly.

Jon Marshall · ‎05-01-2010

When you connect the 520 to the other 520 is there another connection still up to another switch ?

Also how is the port configured that error disables ?

Perhaps a quick diagram would help.

Jon

glengardener · ‎05-01-2010

i am sorry if i am not explaining this clearly.

yes - the ports are active.

diagram (here goes)

port 1-4 on UC520 are configured as switch , auto, auto, auto to the 4 CE520s

i removed the CE520 on port 4 and plugged it into the CE520 switch that was plugged into port 3.

I set the port on CE520 (3) to be switch also plugged the CE520 (4) into it. as soon as i plugged the switch in, the port flashes and the ALERT light appear on both switches and both ports no longer work.

All other devices in the other ports on both switches continue to work and when i connect to the configuration assistant app it shows the message i sent earlier. i then have to disable & renable the port to be able to try again. it doesnt seem to matter what i set the port to, i.e switch, router, other as soon as i plug in the CE520 (4) it disables the port

Jon Marshall · ‎05-01-2010

Glen

I set the port on CE520 (3) to be switch also plugged the CE520 (4) into it. as soon as i plugged the switch in, the port flashes and the ALERT light appear on both switches and both ports no longer work.

What do you mean by this. Is there a setting on the 520 to tell it what type of device you are connecting to the port ?

Jon

glengardener · ‎05-01-2010

yes, i am using Cisco Configuration Assistant to make changes to the switches and the UC520.

It allows me to set the ports to all the avialble options as well as renable the ports

it then sends the appropriate CLI to the switch.

Jon Marshall · ‎05-01-2010

Glen

If the switch is error disabling a port because of receiving a BPDU on the port it sounds like spanning-tree BPDUGuard is enabled on the port(s). Is there a way to do the equivalent of a "sh run" on the 520 to post the current configuration.

Jon