5

I am trying to configure sflow on Nexus 9396PX switch and having some difficulty to understand tcam region.

hardware access-list tcam region span-sflow 256
!
feature sflow
sflow counter-poll-interval 30
sflow collector-ip 10.30.0.91 vrf management
sflow collector-port 9995
sflow agent-ip 172.30.0.26

when i enable on my port-channel1 (which is 4x40G port bundle on GEM module)

sflow data-source interface port-channel1

When i run "show run sflow" to verify config i can't see "sflow data-source interface port-channel1" line there.

N9K(config)# show run sflow

!Command: show running-config sflow
!Running configuration last done at: Tue Apr 13 14:24:00 2021
!Time: Tue Apr 13 14:24:58 2021

version 9.3(6) Bios:version 07.68
feature sflow

sflow counter-poll-interval 30
sflow collector-ip 10.30.0.91 vrf management
sflow collector-port 9995
sflow agent-ip 172.30.0.26

For experiment i tried to add Ethernet 1/1 (10G port) and that works i can see that in "show run" Look like 40G Gem module doesn't supported. so i did google and found this on Cisco website

Make sure that the sFlow and SPAN ACL TCAM region sizes are configured for any uplink ports that are to be configured as an sFlow data source on the following devices: Cisco Nexus 9332PQ, 9372PX, 9372TX, and 93120TX switches and Cisco Nexus 9396PX, 9396TX, and 93128TX switches with the N9K-M6PQ or N9K-M12PQ generic expansion module (GEM).

Question, is what is SPAN ACL region all i can see following on my switch, does SPAN ACL is ing- l2-span-filter or ing-l3-span-filter ?

hardware access-list tcam region span 0
hardware access-list tcam region ing-l2-span-filter 0
hardware access-list tcam region ing-l3-span-filter 0
hardware access-list tcam region ipv6-span-udf 0
hardware access-list tcam region ipv6-span-l2-udf 0
hardware access-list tcam region span-sflow 256
2
  • Not sure about the Nexus, but on many platform you can collect sFlow samples only on physical ports.
    – Zac67
    Apr 13 at 15:53
  • I have tried physical 40G port also but doesn't work, Cisco document saying you can configure Port-Channel for sFlow source interface.
    – Satish
    Apr 13 at 15:56
6

This is the solution, we need both span and sflow tcam size 256, so i took vPC slice and give it to span region (Notes: following solution only apply for 40G Interface, if you are using 10G for data-source then nothing to do)

hardware access-list tcam region vpc-convergence 0
hardware access-list tcam region sflow 256
hardware access-list tcam region span 256

Now i am able to use Port-Channel (4x40G bundle)

feature sflow

sflow counter-poll-interval 30
sflow collector-ip 172.29.0.91 vrf management
sflow collector-port 9995
sflow agent-ip 172.29.0.236

sflow data-source interface port-channel1

sflow stats

N9K# show sflow
sflow sampling-rate : 4096
sflow max-sampled-size : 128
sflow counter-poll-interval : 30
sflow max-datagram-size : 1400
sflow collector-ip : 172.29.0.91 , vrf : management
sflow collector-port : 9995
sflow agent-ip : 172.29.0.236
sflow data-source interface port-channel1

N9K# show sflow statistics
Total Packets        : 4921
Total Samples        : 0
Processed Samples    : 0
Dropped Samples      : 0
Sent Datagrams       : 39
Dropped Datagrams    : 0

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