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.
Is there a new location for this article ? The link leads to a landing page with no results.
CNP packet format:
https://enterprise-support.nvidia.com/s/article/rocev2-cnp-packet-format-example
CNP counters – I do not recommend using this old article (below updated link) as it is relying on some internal registers which might differ between different HW types. The same counters are available in this article: ESPCommunity
ESPCommunity
