How can I get the statistics of DCQCN in CX5 Cards?

Hello.

I was configuring the DCQCN parameters on 100Gbps CX5 cards and ECN thresholds on the Mellanox SN2100 switch.

After I ran some tests(randomly write data from one server to the other server), How could I know if the DCQCN was running during the tests? (equally, could I check the generated/received CNP packets on the server?)

After reading the relevant document HowTo Configure DCQCN (RoCE CC) values for ConnectX-4 (Linux) https://community.mellanox.com/s/article/howto-configure-dcqcn--roce-cc--values-for-connectx-4--linux-x , I got that the default DSCP value is 48 and the default priority is 6 of CNP packets. (Check the path “/sys/kernel/debug/mlx5/cc_parameters/*”)

So I can check the packets counters by using ethtool -S p4p1 | grep "rx_prio6_packets", the result was similar to the following figure:

It showed that packets did occur on the 6th priority tx/rx queue. But how could I identify which packets are CNP packets?

Are there another methods to monitor the CNP packets or other parameters of DCQCN?

Thanks.

Hello.

I tried to capture all the packets issued and received during the test. But I could not find the packets with ECN marked. Couldn’t these control packets be captured by the administrator?

However, I could find the CNP packets like this:

Same format with the RoCEv2 congestion management standard:

But this method for getting the statistics of DCQCN was too expensive. Could someone give some pieces of advice?

Thank you.

Finally, I found the relevant documents.

HowTo Read CNP Counters on Mellanox adapters https://community.mellanox.com/s/article/howto-read-cnp-counters-on-mellanox-adapters

Finally, I found the relevant documents.

HowTo Read CNP Counters on Mellanox adapters https://community.mellanox.com/s/article/howto-read-cnp-counters-on-mellanox-adapters

Hello.

I tried to capture all the packets issued and received during the test. But I could not find the packets with ECN marked. Couldn’t these control packets be captured by the administrator?

However, I could find the CNP packets like this:

Same format with the RoCEv2 congestion management standard:

But this method for getting the statistics of DCQCN was too expensive. Could someone give some pieces of advice?

Thank you.