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New Member

3750 Blinking Amber Lights - Bug?

We recently installed a WS-C3750-48TS-E and loaded the newest Enterprise IOS image on it.

There are a few trunks configured on the switch and there are also about 10 servers connected to it. We periodically get flashing amber lights on only the server ports. Errors occur occasionally on these ports. I have included the controller output of one of the periodic blinking amber ports below.

I opened up a TAC case, but the tech was less than helpful. He quoted the following bug, but this is definitely not the problem.

-------------------------------

CSCec14238

Externally found moderate defect: Verified (V)

3750 connected using dot1q cause Runts increase on interface.

-------------------------------

The Catalyst 3750 documentation states that ports should only blink amber if "the port is blocked by STP and is transmitting or receiving packets". Well, we have "switchport host" issued on each of the server ports with BPDU guard and BPDU filter enabled. I know that the STP port state never changes, so I know this is not the problem. We never lose connectivity to the server when its port is blinking amber.

There are only 2 possibilities that I can think of:

1) The documentation is incorrect - the port blinks amber if there are errors

2) There is a cosmetic bug

-----------------------------------------

aus-core1#show controllers ethernet-controller fast 1/0/38

Transmit FastEthernet1/0/38 Receive

2470495362 Bytes 1518647103 Bytes

24502910 Unicast frames 32513196 Unicast frames

749706 Multicast frames 0 Multicast frames

2956574 Broadcast frames 2608 Broadcast frames

0 Too old frames 1518187216 Unicast bytes

0 Deferred frames 0 Multicast bytes

0 MTU exceeded frames 319302 Broadcast bytes

0 1 collision frames 456 Alignment errors

0 2 collision frames 0 FCS errors

0 3 collision frames 0 Oversize frames

0 4 collision frames 0 Undersize frames

0 5 collision frames 73 Collision fragments

0 6 collision frames

0 7 collision frames 2935484 Minimum size frames

0 8 collision frames 7232091 65 to 127 byte frames

0 9 collision frames 1820568 128 to 255 byte frames

0 10 collision frames 1355735 256 to 511 byte frames

0 11 collision frames 1379397 512 to 1023 byte frames

0 12 collision frames 17792985 1024 to 1518 byte frames

0 13 collision frames 0 Overrun frames

0 14 collision frames 0 Pause frames

0 15 collision frames

0 Excessive collisions 0 Symbol error frames

0 Late collisions 0 Invalid frames, too large

0 VLAN discard frames 0 Valid frames, too large

0 Excess defer frames 73 Invalid frames, too small

15990751 64 byte frames 0 Valid frames, too small

6453030 127 byte frames

1092956 255 byte frames 0 Too old frames

1234441 511 byte frames 0 Valid oversize frames

551685 1023 byte frames 0 System FCS error frames

2886327 1518 byte frames 0 RxPortFifoFull drop frame

0 Too large frames

0 Good (1 coll) frames

0 Good (>1 coll) frames

Receive

1518647103 Bytes

32513196 Unicast frames

0 Multicast frames

2608 Broadcast frames

1518187216 Unicast bytes

0 Multicast bytes

319302 Broadcast bytes

456 Alignment errors

0 FCS errors

0 Oversize frames

0 Undersize frames

73 Collision fragments

2935484 Minimum size frames

7232091 65 to 127 byte frames

1820568 128 to 255 byte frames

1355735 256 to 511 byte frames

1379397 512 to 1023 byte frames

17792985 1024 to 1518 byte frames

0 Overrun frames

0 Pause frames

0 Symbol error frames

0 Invalid frames, too large

0 Valid frames, too large

73 Invalid frames, too small

0 Valid frames, too small

0 Too old frames

0 Valid oversize frames

0 System FCS error frames

0 RxPortFifoFull drop frame

---------------------------------------

Can anyone offer any advise or suggestions?

Thanks,

Jordan

5 REPLIES
New Member

Re: 3750 Blinking Amber Lights - Bug?

Well, I think I found the problem. It appears that the 3750 port lights will blink amber when errors occur on a port (which indicates and error with the switch documentation). I was using an older Intel Pro/100+ driver on numerous servers connected to the switch. The older drivers were generating alignment errors and collision fragments periodically. I upgraded to the new version of the Intel drivers and haven't received further errors. Since the upgrade, I haven't seen the lights flash amber

It would be nice if Cisco could confirm or deny my findings...

Jordan

New Member

Re: 3750 Blinking Amber Lights - Bug?

There is a bug that addresses this issue, CSCec53648. Basically, the interface LED will blink amber when receiving valid dot1q packets which are less than 68 bytes (tag included). This will be expected behavior and no fix. Hope this helps.

New Member

Re: 3750 Blinking Amber Lights - Bug?

Our problem is a different bug that has not yet been reported. This problem is not related to the above issue because it has nothing to do with trunks. We have portfast enabled on the ports with the global bpdufilter command enabled, so all BPDU's should be blocked anyway. We were seeing both collision fragments and algnment errors on the ports, which appeared to fire off the amber lights. We updated the Intel NIC drivers on the servers and that eliminated the port errors, which in-turn eliminated the blinking amber lights.

New Member

Re: 3750 Blinking Amber Lights - Bug?

The bug states that Runts will trigger the LED to flash amber. What I meant was any packets less than 68 bytes with a dot1Q tag .. which would bring it below 64 bytes w/o the tag .. which is a Runt.

New Member

Re: 3750 Blinking Amber Lights - Bug?

Then that must be it. I did notice some "collision fragments", which I would assume would be runts.

Thanks for your help!

Jordan

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