Symptoms
A Fibre Channel interface is disabled and has the following status even though the bit error rate of the interface is below the threshold specified in the Fibre Channel standards:
fc1/1 is down (Error disabled - bit error rate too high)
The following type of syslog messages are logged for the interface:
%PORT-5-IF_DOWN_BIT_ERR_RT_THRES_EXCEEDED: %$VSAN 1%$ Interface fc1/1 is down (Error disabled - bit error rate too high)
%MODULE-4-MOD_WARNING: Module 1 (Serial number: JAF1234567) reported warning on ports fc1/1 (Fibre Channel) due to MAC Bit error exceeded threshold in device DEV_TBIRD_MAC (device error 0xc9a01503)
Cause
Cause can be related to
CSCuo56792, but note there is also a physical infra issue that needs to be addressed.
To determine if this bug has been hit, use the following command -
show process creditmon event-history 9) Event:CREDITMON_EVENT_ERR_COUNT, length:46, at 446583 usecs after Tue Apr 29 23:20:25 2014 port : cur=0x6ff4 prev=0x6ff3 occurances=15 21) Event:CREDITMON_EVENT_ERR_COUNT, length:46, at 946708 usecs after Sat Apr 26 19:57:48 2014 port : cur=0x6fe7 prev=0x6fe6 occurances=1
If occurances=15 happens after 5 minutes of occurances=1 then this bug has been hit for port fcx/y.
If occurances=15 happens within 5 minutes of occurances=1, then this bug has not been hit.
Resolution
Workaround:
Fix the physical layer. Usually the cable run or patch panel or the sfp/hba at the other end of the cable run.
The SFP on the switch is detecting the problem, not causing the problem and should only be replaced after replacing the cable run or laser at the other end of the cable run.
Even though the rate of bit errors on the affected link may not have been at as high as the rate specified in the Fibre Channel standards, there were still bit errors occurring. This causes the interface to be error disabled prematurely. However, persistent bit errors on a link are undesirable and the problem should still be corrected.
This bug is adddresed in NX-OS 5.2(8e) and above in the 5.2 line of code and fixed in 6.2(11) and above in the 6.2 and above lines.
Affected Products
Connectrix MDS-Series Hardware
Products
Connectrix MDS-Series Firmware 5.X, Connectrix MDS-Series Firmware 6.X, Connectrix MDS-Series Hardware