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Cisco Employee

Nexus C9504 bitrate measurements show 'jump' every 3 min

Hi all

I just started monitoring the bitrate of a portchannel, and the underlying physical ports, of a C9504 (NXOS: version 7.0(3)I1(2))

What i see is a spike of double the 'nominal' bitrate every 3min or so :

This is a screenshot of a Zabbix graph using SNMP to get the ifHCInOctets and ifHCOutOctets.  It shows the portchannel + the 2 interfaces that are part of the portchannel (eth1/1 and 1/2)

The spikes can be seen both on in- and egress, on the portchannel and the physical interfaces

The spike frequency is the same for all ports (every 3 min) but the spikes are shifted in time

The only traffic going over this link is SSM video traffic form host-A <> host-B.  If i disable the video stream the bitrate goes to zero and the spikes are gone.  What is strange is that the spikes are double the actual bitrate ...

I took a capture of the multicast stream on one of the UCS servers connected to this switch and ran it trough wireshark to see if the bitrate does really peak, but it shows me a perfectly flat bitrate :

the first zabbix graph shows the bitrate (=delta between previous and current measurement) and the below graph shows the absolute value if the ifHCOutOctets / ifHCInOctets values.  At first a thought that the jump occurred when the counter wraps, but that is not the case :

(i have indicated the 'jumps' in red)

Cisco Employee


i just upgraded to version 7.0(3)I4(5) on both C9504 and C9332PQ and the issue is still present  :-(

very annoying since this makes it hard to define sensible bitrate triggers in my monitoring system


So, was this ever fixed? I'm running NXOS: version 7.0(3)I4(3) on Nexus 3064PQ and have the same issue.

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