Strange log message from ERS 8600 Release 7.2.17

[pat2012]

Hi folks.

I need some help interpreting a message I got in the log of an ERS 8600 Release 7.2.17.

CPU5 [10/30/17 14:57:35] COP-SW INFO Slot 3: Recovering the port 12 which was locked due to backpressure stuck

Some background.

Slot 3 is an 8812XL - 12-port SFP+

Port 12 is an SLT with an ERS 5632.  The 5632 stopped working after a power failure (affecting all switches).  After checking the log on one of the 8600's in the cluster, I saw the message above being repeated.  Disconnecting the uplink on the 5632 to the 8600 with the errors restored connectivity.

This is the first time I've ever seen this error.  It sounds more like a problem for an auto mechanic.   

No other ports on the 8812XL have the error.  They are also SLTs (for the most part).

KHI stats don't show any issues.  Right lane looks OK.

Do you guys have any idea what that message could mean?

Thanks.

[MatzeKS]

Avaya Support - Search result:

Reasons for Backpressure and Lane Lockup:
 
Backpressure-
 
In the current architecture F2I asic is responsible for receiving incoming traffic from MAC device and transmitting the same to ingress RSP via SPI interface and also putting the traffic back from the RSP to fabric to egress. Due to some unknown reasons, if SPI interfaces can’t carry the traffic can cause memory pages used to store the incoming traffic to get filled up completely or issues in draining out the the packets can result in backpressure which causes lane stuck conditions. Currently our software detects if any lane was is stuck state for 5 seconds then it recovers by reloading the module.
 
 
Lane Lockup-
 
The F2I lane lock up can occur if its SPI buses got some issues due to some unknown reasons or when fabric couldn’t service/handle the surge of heavy incoming traffic.
The lane lock up seen on lane could also be due to a high surge in the traffic which could not get forwarded to the egress queue. We could see, log message at the time of exception indicating that there were some drops seen at the egress queue.

Cause
Product is functioning as designed.

Solution
Line Card software keeps track of health of its components and takes necessary recovery actions when any issue is seen with its components. F2I lockup is a condition where the asic is in bad state and won't be able to deliver the packets to either RSP or fabric. If this condition is detected, line card needs to be rebooted otherwise ports on the affected lanes won't be able to process any received traffic, creating a black hole for the received traffic.
 
Work Around: Distribute the traffic evenly on all the ports/slots on the Switch.

 

[pat2012]

Thanks MatzeKS.

What document did you get the information from?  Did the search point you to a particular document?

It's interesting that they seem to suggest that all ports in a lane should be affected.  However, in my case, port 9 is in the same lane as port 12 (which reported the errors), but port 9 continues to operate normally.

Thanks again.