Cisco N5K-M1600 - Expansion Module - 6 Ports Troubleshooting Manual page 38

PFC
S e n d d o c u m e n t c o m m e n t s t o n e x u s 5 k - d o c f e e d b a c k @ c i s c o . c o m .
Solution
Identify the source of the congestion and try to resolve it by increasing the FC bandwidth or change it
to a more powerful server. If congestion is expected, then Pause is expected for FCoE traffic.
Switch ports err-disabled due to pause rate-limit
Switch ports go into error-disable state due to pause rate limit
Possible Cause
If the switch interface receives excessive Xoff pause frames from the server, ports become error-disabled
due to the high rate of pause frames received. Usually the port goes into an err-disable state due to pause
frames, only if the drain rate is less than 5Mbps on a 10Gb port. This means that the server is very slow
and is sending a large number of pause frames to the switch ports.
To verify this situation, use the show interface ethernet 1/14 brief command.
Example:
switch# show int eth1/14 brief
--------------------------------------------------------------------------------
Ethernet
Interface
--------------------------------------------------------------------------------
Eth1/14
•
•
Solution
Pause error-disable recovery can be enabled to get the ports out of this state, if the port is error-disabled
due to transient condition as follows:
If the port is error-disabled due to transient condition listed below, then pause error-disable recovery can
be enabled to move the ports out of this state.
•
•
If there is a consistent port error-disable condition due to the pause rate limit, determine if the issue is
that the server is too slow. Replace the slow server.
Cisco Nexus 5000 Series Troubleshooting Guide
2-14
Example:
Per-priority-pause status
If the Rx (Active) and pause RX counter increment (as shown with the show interface ethx/x
priority-flow-control command), then this indicates that this issue is due to Xoff frames received
from the server.
If the Tx(Active) and pause TX counter increment (as shown with the show interface ethx/x
priority-flow-control command), this indicates that this issue is due to Xoff frames transmitted by
the switch.
VLAN Type Mode
110 eth trunk
Check if the RX pause count is a large value. Use the show interface ethx/x command to display
the pause counters.
Check for pause error-disable logs using the show hardware internal gatos event-history errors
|grep -i err command.
Error-disable recovery causes the pause rate limit.
The error-disable recovery interval is 30.
: Rx (Active), Tx (Inactive)
Status Reason
down pauseRateLimitErrDisable
Chapter 2 Troubleshooting FCoE Issues
Speed Port
Ch #
100(D) 110
OL-25300-01