ECN IXIA test for verifying equal marking due to traffic causing cong…

…estion (#15849)

Description of PR
Summary:
Fixes # (issue)

Approach
What is the motivation for this PR?
Make the test case multi Topo capable.
Add ecn marking ratio check for flow percent where both

lossless TC are >= 50 to have equal marking

How did you do it?
Ixia testcase enhancement

How did you verify/test it?
On Ixia connected DUT

co-authorized by: jianquanye@microsoft.com

tests/snappi_tests/multidut/ecn/files/multidut_helper.py

@@ -142,11 +142,17 @@ def verify_ecn_counters_for_flow_percent(ecn_counters, test_flow_percent):
                             'Must not have ecn marked packets on flow 4, percent {}'.
                             format(test_flow_percent))
 
-        if test_flow_percent[0] == 50 and test_flow_percent[1] == 50:
+        if test_flow_percent[0] >= 50 and test_flow_percent[1] >= 50:
             pytest_assert(
                             flow3_ecn > 0 and flow4_ecn > 0,
                             'Must have ecn marked packets on flows 3, 4, percent {}'.
                             format(test_flow_percent))
+            flow_ecn_ratio = round(float(flow3_ecn/flow4_ecn), 2)
+            pytest_assert(
+                        round(abs(flow_ecn_ratio - 1), 3) <= 0.05,
+                        "The packet flow ecn ratio {} deviation more than tolerance for \
+                        flow percent {} flow 3 ecn -> {} flow 4 ecn -> {}".
+                        format(flow_ecn_ratio, test_flow_percent, flow3_ecn, flow4_ecn))
 
 
 def run_ecn_test(api,

tests/snappi_tests/multidut/ecn/test_multidut_ecn_marking_with_snappi.py

@@ -2,18 +2,19 @@
 import logging
 from tabulate import tabulate # noqa F401
 from tests.common.helpers.assertions import pytest_assert     # noqa: F401
-from tests.common.fixtures.conn_graph_facts import conn_graph_facts, fanout_graph_facts_multidut         # noqa: F401
+from tests.common.fixtures.conn_graph_facts import conn_graph_facts, fanout_graph_facts, \
+    fanout_graph_facts_multidut         # noqa: F401
 from tests.common.snappi_tests.snappi_fixtures import snappi_api_serv_ip, snappi_api_serv_port, \
     snappi_api, snappi_dut_base_config, get_snappi_ports, get_snappi_ports_for_rdma, cleanup_config, \
-    is_snappi_multidut, get_snappi_ports_multi_dut   # noqa: F401
+    is_snappi_multidut, get_snappi_ports_multi_dut, get_snappi_ports_single_dut   # noqa: F401
 from tests.common.snappi_tests.qos_fixtures import prio_dscp_map, \
     lossless_prio_list, disable_pfcwd   # noqa F401
 from tests.snappi_tests.files.helper import multidut_port_info, setup_ports_and_dut  # noqa: F401
 from tests.snappi_tests.multidut.ecn.files.multidut_helper import run_ecn_marking_test, run_ecn_marking_port_toggle_test
 from tests.common.snappi_tests.snappi_test_params import SnappiTestParams
 from tests.common.cisco_data import is_cisco_device
 logger = logging.getLogger(__name__)
-pytestmark = [pytest.mark.topology('multidut-tgen')]
+pytestmark = [pytest.mark.topology('multidut-tgen', 'tgen')]
 
 
 def validate_snappi_ports(snappi_ports):
@@ -110,7 +111,7 @@ def test_ecn_marking_port_toggle(
         cleanup_config(duthosts, snappi_ports)
 
 
-test_flow_percent_list = [[90, 15], [53, 49], [15, 90], [49, 49], [50, 50]]
+test_flow_percent_list = [[90, 15], [53, 49], [15, 90], [49, 49], [50, 50], [60, 60], [60, 90], [90, 60]]
 
 
 @pytest.mark.parametrize("test_flow_percent", test_flow_percent_list)