Netvanta 7100 Ports 1-24 LED Indicators Blink Simultaneously

[Anonymous]

Hi all,

Don't know if this is an issue but have always received complaints from one of our sites reporting that the "system is slow".  As no complaints have been received from any of the other sites I'm looking into the local network for possible problems.  The Default Gateway is a Netvanta 7100 which also supports our VOIP system at that site.  I have noticed that all port LED indicators (1-24) blink amber simultaneously quite often.  By often I mean that it will do this every few seconds.  From what I understand, blinking signifies activity on each on the ports but having them all blink simultaneously could be signs of collisions.  In your opinion, does this indicate a problem on the network?  If so, what do you recommend as the first steps in troubleshooting the issue?

Thank you.

[jayh · Accepted solution]

Seeing all of the ethernet interface activity lights blink in unison is usually an indication of a broadcast or possibly multicast packet. This is typical for ARP requests and the like.  Every few seconds isn't typically a problem. This activity can be generated by the voice network or the data network.

Collisions are an indication of half-duplex and should only affect a single interface at a time.

Wireshark on an otherwise unused port will show broadcast activity. 

[Anonymous]

Thx.  That's next on my to-do list.

[Anonymous]

juad,

    It could also be an indication of a network loop I have seen it many times where a user will see a loose network cable and go ahead and plug it trying to be helpful.  Where this gets to be bad is lets say the plugged in end of the cable is in a phone PC port and they plug it right back into an empty jack that goes back the switch.  This causes the phone to show up on two ports at the same time on the switch which causes a network loop.  Normally then spanning tree kicks in and shuts down one of the two ports for awhile but depending on its configs it will turn the port back on from time to time to see if the loop is gone.  Normally if this is the case you will notifications show up when logged into the cli you can also try debug spanning-tree events and let it the debug running for a few minutes, normally there should be no events so no results is a good thing, if you get events coming up every few seconds then you know where to start looking.  Another thing to watch for is duplex mismatch messages showing up I have had to shut down lldp send-and-receive from time to time to avoid duplex mismatches if using equipment that has forced speed and or duplex settings to avoid this.

John Wable

[jayh]

Any update here?  A broadcast packet every few seconds blinking all of the lights isn't likely to be of concern, in fact it's typical.  I'd look elsewhere regarding the complains of slowness.  Check for duplex mismatches, virus/botnet traffic, cabling problems and the like.