Cisco N5K-M1600 - Expansion Module - 6 Ports Troubleshooting Manual page 36

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 .
Use the following information to verify DCBX support and that the PFC TLV is negotiated:
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Switch Interface connected to CNA receives constant pause frames (PFC)
Constant pause frames (PFC) are received when the switch interface is connected to a CNA.
Possible Cause
If the Nexus 5000 switch is connected to a CNA, then the CNA might be sending Xon PFC frames to the
switch. This increments pause counters when using the show interface ethx/x command.
To verify this situation, perform the following:
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Cisco Nexus 5000 Series Troubleshooting Guide
2-12
Check the status of the PFC. Use the show int ethx/x priority-flow-control command.
(Connected to CNA.)
Example:
switch# show interface ethernet 1/13 priority-flow-control
============================================================
Port Mode Oper(VL bmap)
============================================================
Ethernet1/13 Auto Off
Check for LLDP neighbor or PFC/DCBX TLV advertised by the peer. Use the show system internal
dcbx info int ethx/x command.
Example:
switch(config-if)# show system internal dcbx info interface ethernet 1/1
Interface info for if_index: 0x1a000000(Eth1/1)
tx_enabled: FALSE
rx_enabled: FALSE
dcbx_enabled: TRUE
DCX Protocol: CIN
Port MAC address: 00:0d:ec:c9:c8:08
DCX Control FSM Variables: seq_no: 0x1, ack_no: 0x0,my_ack_no: 0x0, peer_seq_no:
0x0 oper_version: 0x0,
Lock Status: UNLOCKED
PORT STATE: UP
LLDP Neighbors
No DCX tlvs from the remote peer
If the peer does not support DCBX, configure the priority-flow-control mode setting to on to enable
PFC.
For a few iterations, check using the show interface ethx/x command and make sure the pause
frame count is incrementing using the show interface ethx/x |grep - i pause command.
For a few iterations, check using the show interface ethx/x command and ensure that the PFC
frame count is incrementing using the show interface ethx/x priority-flow-control command.
For a few iterations, use the show queuing interface ethx/x command to check the pause status.
Example:
Per-priority-pause status
RxPPP
0 0
max_version: 0x0 fast_retries 0x0
: Rx (Inactive), Tx (Inactive)
Chapter 2 Troubleshooting FCoE Issues
TxPPP
OL-25300-01