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Pause frames on blade interfaces, what is expected?

I am putting together a UCS runbook for an operational team to use to help with troubleshooting Cisco UCS. I was leveraging some Cisco Live presentations including 'BRKCOM-3002 - UCS Performance Troubleshooting'. In this presentation, when looking at congestion inside UCS the presenter makes a reference to check for pause this customer's environment I ran the same command for documenting the procedure and noticed many Tx pause frames. Is this normal? Unfortunately I have never checked these counters in other environments so I have nothing to base it off. There are 0 pause frames on LAN uplink interfaces and only a few 100 pause frames on the server downlink interfaces to the FEX. This environment is running VMware ESXi 5.5 U1.


ucs-A(nxos)# show interface ethernet 1/1/1 priority-flow-control
Port               Mode Oper(VL bmap)  RxPPP      TxPPP

Ethernet1/1/1      Auto On  (18)      0          607998


As you can see there are many pause frames being sent from the blades...


Ethernet1/1/1      Auto On  (18)      0          607998
Ethernet1/1/2      Auto Off           0          0
Ethernet1/1/3      Auto On  (18)      0          647302
Ethernet1/1/4      Auto Off           0          0
Ethernet1/1/5      Auto On  (18)      0          686730
Ethernet1/1/6      Auto Off           0          0
Ethernet1/1/7      Auto On  (18)      0          613622
Ethernet1/1/8      Auto Off           0          0
Ethernet1/1/9      Auto On  (18)      0          447698
Ethernet1/1/10     Auto Off           0          0
Ethernet1/1/11     Auto On  (18)      0          479446
Ethernet1/1/12     Auto Off           0          0
Ethernet1/1/13     Auto On  (18)      0          429074
Ethernet1/1/14     Auto Off           0          0
Ethernet1/1/15     Auto On  (18)      0          406480


And 0 pause frames on LAN uplinks Eth1/1-4 and not many on the server downlinks Eth1/9-16.

Ethernet1/1        Auto Off           0          0
Ethernet1/2        Auto Off           0          0
Ethernet1/3        Auto Off           0          0
Ethernet1/4        Auto Off           0          0
Ethernet1/5        Auto Off           0          0
Ethernet1/6        Auto Off           0          0
Ethernet1/7        Auto Off           0          0
Ethernet1/8        Auto Off           0          0
Ethernet1/9        Auto Off           96         414
Ethernet1/10       Auto Off           16         362
Ethernet1/11       Auto Off           24         410
Ethernet1/12       Auto Off           18         452
Ethernet1/13       Auto Off           26         318
Ethernet1/14       Auto Off           402        354
Ethernet1/15       Auto Off           876        308
Ethernet1/16       Auto Off           114        310


If I am pointing operational administrators to go check counters then I want to be clear what are expected returns. Any insight is appreciated.






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I have seen this in multihop FCoE installations, specially with problems of FCoE disk arrays.