[Snappi] Modifications to pfcwd a2a test design for mlnx 4600c (#7367)

* changes to pfcwd a2a test for mlnx 4600c

* changes to pfcwd a2a test for mlnx 4600c

* modified test case to take in platform as parameter

* changed from platform to asic_type

Author: developfast

tests/snappi/pfcwd/files/pfcwd_multi_node_helper.py

@@ -125,6 +125,9 @@ def run_pfcwd_multi_node_test(api,
     speed_str = testbed_config.layer1[0].speed
     speed_gbps = int(speed_str.split('_')[1])
 
+    """ Retrieve ASIC information for DUT """
+    asic_type = duthost.facts['asic_type']
+
     __verify_results(rows=flow_stats,
                      speed_gbps=speed_gbps,
                      pause_flow_name=PAUSE_FLOW_NAME,
@@ -136,7 +139,8 @@ def run_pfcwd_multi_node_test(api,
                      data_pkt_size=DATA_PKT_SIZE,
                      trigger_pfcwd=trigger_pfcwd,
                      pause_port_id=port_id,
-                     tolerance=TOLERANCE_THRESHOLD)
+                     tolerance=TOLERANCE_THRESHOLD,
+                     asic_type=asic_type)
 
 
 def __data_flow_name(name_prefix, src_id, dst_id, prio):
@@ -517,7 +521,8 @@ def __verify_results(rows,
                      data_pkt_size,
                      trigger_pfcwd,
                      pause_port_id,
-                     tolerance):
+                     tolerance,
+                     asic_type):
     """
     Verify if we get expected experiment results
 
@@ -534,10 +539,15 @@ def __verify_results(rows,
         trigger_pfcwd (bool): if PFC watchdog is expected to be triggered
         pause_port_id (int): ID of the port to send PFC pause frames
         tolerance (float): maximum allowable deviation
+        asic_type (str): asic_type information for DUT
 
     Returns:
         N/A
     """
+
+    """ Check for whether DUT is a Mellanox device """
+    is_mlnx_device = True if "mellanox" in asic_type.lower() else False
+
     for row in rows:
         flow_name = row.name
         tx_frames = row.frames_tx
@@ -568,11 +578,16 @@ def __verify_results(rows,
             exp_test_flow_rx_pkts =  test_flow_rate_percent / 100.0 * speed_gbps \
                 * 1e9 * data_flow_dur_sec / 8.0 / data_pkt_size
 
-            if trigger_pfcwd and\
-               (src_port_id == pause_port_id or dst_port_id == pause_port_id):
+            if trigger_pfcwd and dst_port_id == pause_port_id:
                 """ Once PFC watchdog is triggered, it will impact bi-directional traffic """
                 pytest_assert(tx_frames > rx_frames,
                               '{} should have dropped packets'.format(flow_name))
+            
+            elif trigger_pfcwd and src_port_id == pause_port_id:
+                if is_mlnx_device:
+                    """ During a pfc storm with pfcwd triggered, Mellanox devices do not drop Rx packets """
+                    pytest_assert(tx_frames == rx_frames,
+                                  '{} should not have dropped packets for Mellanox device'.format(flow_name))
 
             elif not trigger_pfcwd and dst_port_id == pause_port_id:
                 """ This test flow is delayed by PFC storm """