[c-nsp] Strange X2 Temperature Flaps

Drew Weaver drew.weaver at thenap.com
Thu Mar 17 11:44:07 EDT 2016

If the X2 modules are exactly 6 months old, or they have been running for exactly 6 months when this started, get rid of them and switch to Cisco branded optics.

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Robert Williams
Sent: Thursday, March 17, 2016 11:37 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Strange X2 Temperature Flaps


Within 48 hours we have had three very strange issues with three different X2 modules, installed in 2 different chassis (both in 6708-10G/Sup720/6509E). In each case, the module's temperature reading has jumped and then oscillated from +127C to -127C over the course of the next 5 hours.

Each time it completes a loop it jumps from -127 to +127 - at _that_ moment we get a short burst of CRC errors in the ASR9k which is connected to the other end of the link. In two of the cases so far, the errors were enough to trip OAM on the ASR9k into err-disable on the port due to >3 seconds of symbol errors.

[Example image of temperature Vs. time is attached.]

So far this has hit us on:

 - 3 different X2 modules
 - in 2 different line cards
 - in 2 different chassis
 - within a 48 hour window

Chassis are at the same geographic site but several racks apart. Modules are 10G-LR SM optics, mixed brands. Chassis are 6509-E running 15.1(2)SY5 with around 260 days uptime each.

So apart from being powered on for a similar amount of days, I can find absolutely nothing related which may be causing this.

If you login to the chassis and repeatedly read the temperature from the transceiver (sh int te2/8 trans) you get a slightly different (+/- 5 degrees) value each time, but always tracking the same steady decrease (until -127, then it jumps again).

In many years of operating this type of hardware I’ve never seen this happen before. Anyone have any ideas or advice?

Any input most welcome!


Robert Williams
Custodian Data Centre
Email: Robert at CustodianDC.com

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