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N300 WNR2000v5 causes Cisco switch to err-disable port

lisacoody
Tutor

N300 WNR2000v5 causes Cisco switch to err-disable port

I manage Cisco switches in our student dormitory buildings and am trying to figure out why this particular Netgear wifi router is causing the student's port to err-disable. I have spanning-tree configured and bpduguard enabled on the Cisco switches. I've tried re-enabling the port with shut / no shut but it keeps err-disabling. This is the error I get "SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port GigabitEthernet0/33 with BPDU Guard enabled. Disabling port." 

 

Does the Netgear WNR2000 / N300 wifi router send BPDU's? I can't find anything regarding spanning-tree in the user manual.

 

Thanks in advance!

 

Lisa

Model: WNR2000v5|N300 WiFi Router
Message 1 of 8
ElaineM
NETGEAR Employee Retired

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Hi @lisacoody Have you tried using a different router?

The NETGEAR router is not capable of disabling the port.

Can you give us a the network topology with details together with the complete model of the switch?

ElaineM
NETGEAR Community Team
Message 2 of 8
lisacoody
Tutor

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Hi Elaine. Thanks in advance for trying to help me with this. I appreciate your time and any advice you can give me.

 

I have not tried using a different router yet. The student uses her Netgear router to connect a DVD player, phone, and laptop via wifi.

 

Below is the network topology. The student is in building 3b and is connected to the .136 switch - a Cisco 48-port 3650E. Spanning-tree Portfast and BPDU Guard are globally enabled (configured by Cisco TAC). The red lines that connect the switches are fiber trunks.

 

topology drawing.jpg

Message 3 of 8
netwrks
Master

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

If you have a small unmanaged switch, try putting it between the Netgear and the Cisco switch, and see if that resolves your Span Tree issue.

Message 4 of 8
lisacoody
Tutor

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Interesting idea! I'm working with a Cisco TAC engineer to find out what's going on, but if he can't offer any solutions, then I'll definitely try it. Thanks!

Message 5 of 8
netwrks
Master

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Can you sniff the port on the Cisco to see what is going on? As you aren't going to get much info from the NG device. Or maybe the Cisco TAC has already asked for a trace.. 

Message 6 of 8
lisacoody
Tutor

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Yes netwrks, we created a span session on the 3560 and did a packet capture yesterday afternoon. I submitted the .pcap file to the Cisco engineer and I'm waiting on him to get back with me on what he found.

 

There are now 3 other ports on the same switch that have been err-disabled by bpduguard. I don't know what type devices they are yet, but I'm assuming they are wifi routers (this is a student dormitory setting). 

Message 7 of 8
lisacoody
Tutor

Re: N300 WNR2000v5 causes Cisco switch to err-disable port

Well, no luck with TAC (so far). He thinks it might be a faulty cable somewhere causing bpdu's to be reflected. I replaced the patch cables in my IDF and left some spares for students to pick up and replace the patch in their room.

 

netwrks - I tried putting a Linksys 8-port gigabit switch (EG008W) inline with one of the connections that keeps err-disabling and it err-disabled the port the Linksys was plugged into. I had my laptop plugged in on one of the other Linksys ports and was working great until I added the other connection. I tried it twice just to make sure it wasn't a fluke. 

 

 

Message 8 of 8
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