[2405][BRCM-DNX] show queue counter shows incorrect Tx packets with Pause frames received on egress port.

[amitpawar12]

Description

Scenario:
When lossless traffic is sent via the DUT and Pause frames are sent on the egress, the egress goes into stormed mode.

Since PFCWD and Credit-WD is enabled, all the packets get dropped and no lossless packet is sent out of the egress.

In 2205, for duration of storm detection few packets would be sent out, after which packets are completely stopped out of egress.

The queue counter would show ONLY packets sent out under 'Counter/pkts' and rest of dropped packets would be displayed under 'Drop/pkts'. So if ingress sends A packets to egress and egress drops B packets, 'Counter/pkts' is A-B and 'Drop/pkts' is B packets.

However, in 2405, 'Counter/pkts' shows all the packets received on the interface and dropped packets are incremented under 'Drop/pkts'. So, if ingress sends A packets to egress and egress drops B packets, 'Counter/pkts' is A and 'Drop/pkts' is B packets.

Example of 2205:

admin@ixre-egl-board72:~$ sudo ip netns exec asic0 show queue counters --nonzero
Ethernet0 Last cached time was 2024-12-03 20:09:17.303866
     Port    TxQ    Counter/pkts    Counter/bytes    Drop/pkts       Drop/bytes
---------  -----  --------------  ---------------  -----------  ---------------
Ethernet0    UC3         126,497      127,508,976  421,358,651  424,729,520,208
Ethernet0    UC4         890,415      897,538,320  421,532,480  424,904,739,840
Ethernet0    UC7              19            4,902            0                0

Example of 2405:

admin@ixre-egl-board71:~$ show queue counters -n asic0  --nonzero
     Port    TxQ    Counter/pkts    Counter/bytes    Drop/pkts    Drop/bytes
---------  -----  --------------  ---------------  -----------  ------------
Ethernet0    UC3       603846010     608676778080    603717878  608547621024
Ethernet0    UC4       603898579     608729767632    603780253  608610495024

Steps to reproduce the issue:

1. Enable PFCWD and Credit-WD on the DUT.
2. Send Pause Storm on the egress, storming the egress port.
3. Attempt to send lossless traffic via the egress port.
4. Check the queue stats.

Describe the results you received:

In 2205, the 'Counter/pkts' would ONLY show the packets which are Tx'ed out of the box.

In 2405, behavior has changed, and stats shows cumulative packets received from ingress.

Describe the results you expected:

Consistent behavior across 2205 and 2405. Queue stats should show ONLY the Tx'ed packets out of egress rather than showing cumulative counter.

This will affect 'Snappi' sonic-management testcases where PAUSE is received on egress and 'verify_egress_queue_frame_count' is being called to check the queue-counter in event of PAUSE being received.

We have raised Broadcom issue - CS00012381231 to track the same.

Tagging @saksarav-nokia

Output of show version:

SONiC Software Version: SONiC.HEAD.884690-202405-281b4a58
SONiC OS Version: 12
Distribution: Debian 12.8
Kernel: 6.1.0-22-2-amd64
Build commit: 281b4a58
Build date: Fri Nov 22 08:05:41 UTC 2024
Built by: gitlab-runner@sonic-build-server03

Platform: x86_64-nokia_ixr7250e_36x400g-r0
HwSKU: Nokia-IXR7250E-36x100G
ASIC: broadcom
ASIC Count: 2
Serial Number: XXXXXXX
Model Number: XXXXXXXXX
Hardware Revision: XX
Uptime: 20:28:01 up  3:41,  1 user,  load average: 1.52, 1.46, 1.34
Date: Tue 03 Dec 2024 20:28:01

Output of show techsupport:

(paste your output here or download and attach the file here )

Additional information you deem important (e.g. issue happens only occasionally):

[saksarav-nokia]

In SAI 11.2, SAI_QUEUE_STAT_PACKETS & SAI_QUEUE_STAT_BYTES returns GREEN packets/bytes + GREEN_DROP packets/bytes whereas in SAI 7.1, it returns only GREEN packets/bytes. Created a csp CS00012381231

[prabhataravind]

Handled by BRCM CSP