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New Member

3550 Kicked off of Network

I have a Linksys RV042 doing routing/dhcp ( and a 3550 ( as my switch.

I recently added a second 3550 connected directly to the router (

Now I've reset all settings to factory defaults on both switches, whenever I plug the 2nd 3550 into the router, this kicks off the 1st 3550 and I'm not able to ping the any of the switchs, now if I have the 2nd 3550 connected, and I plug in the 1st 3550, the same thing happens.

I need to then reset the router and have only one of the switches plugged in to get connectivity.

The switches work fine on their own, but whenever they are plugged into the same router I have this issue; I've also tried this with a different router with the same results.

Any help is appreciated.

Cisco Employee

Re: 3550 Kicked off of Network


Did you check the logs on the switches ? Check " show logging and see if you get any unusual error messages.

Did you check the Spanning-tree port states while this happens on the switches? Check the STP port states for both the port and Vlan and paste the output here.

Is there any need to connect both the switches directly to the router. You can connect 1st 3550 to the router and then uplink 2nd 3550 to the 1st 3550. This should work for you. Try doing that and let us know your findings.

HTH,Please rate if it does.

-amit singh

New Member

Re: 3550 Kicked off of Network

I reflashed the 2nd 3550 and connected it to the router again, this time both switches worked. I rebooted both switches and the router to make sure everything was working, Switch 1 was working, but I got this error on Switch 2:

Description: Fa0/48: Unexpected BPDU received. Port has been Disabled

I was playing around with Smartports and had setup a Cisco-Router role on port 48, I reset the port and everything was fine.

One more reboot of the system to make sure there weren't any issues, and I had the same result as my original post: Switch 2 would kick off Switch 1 and I couldn't ping either switch.

The logs were clean, I'll try uplinking the two switches together next, but there shouldn't be any problems with the switches connected to the router.

Any suggestions?


Re: 3550 Kicked off of Network

Can't imagine why that would be if indeed the switches were set to defaults, I would verify both are indeed both at defaults . Also delete the vlan.dat file and this will make sure any previous layer 2 vlans are removed .

New Member

Re: 3550 Kicked off of Network

I've tried setting up an uplink between the two switches using these commands on both:


conf t

int fa0/47

no spanning-tree portfast

speed 100

duplex full


copy run start

which doesn't work at all.

Attached is the config file I use on both switches with the only differences being the ip address

New Member

Re: 3550 Kicked off of Network

I did some logging and monitored each switch via the network console, while plugging them both into the router, nothing out of the ordinary was shown or logged.

The two switches don't have the same MAC or the same host name.

I interconnected both switches via a crossover cable, and everything is ok, I assumed connecting both switches via a straight through cable would work, or at best the the switch would auto negotiate the connection, like some of the other linksys switches, anyone know why cisco switches don't do this?

Connecting each switch to the linksys RV042 still has the same problem as before, I'm assuming this router doesn't deal with STP too well, would a Cisco 800 or 1800 series router fix this issue?

And on a totally unrelated issue, one of the CAT5e cables going from one of the servers to the 3550 switch was too short, so I made this extension:

except when I plugged it into the cisco switch, nothing was detected. I plugged the same extension into a cheap linksys switch, and it worked just fine. I eventually got a longer cable and used that, but anyone know why the cisco had this behavior?