Stabilize stress ARP test (#16662)

tests/arp/test_stress_arp.py

@@ -78,6 +78,8 @@ def add_arp(ptf_intf_ipv4_addr, intf1_index, ptfadapter):
                                           hw_snd=arp_src_mac,
                                           hw_tgt='ff:ff:ff:ff:ff:ff'
                                           )
+        # Add a short delay to avoid packet loss
+        time.sleep(0.001)
         testutils.send_packet(ptfadapter, intf1_index, pkt)
     logger.info("Sending {} arp entries".format(ip_num))
 
@@ -121,7 +123,7 @@ def test_ipv4_arp(duthost, garp_enabled, ip_and_intf_info, intfs_for_test,
                 # The entries we add will not exceed 10000, so the number we tolerate is 100
                 logger.debug("Expected route number: {}, real route number {}"
                              .format(arp_available, get_fdb_dynamic_mac_count(duthost)))
-                pytest_assert(wait_until(20, 1, 0,
+                pytest_assert(wait_until(40, 1, 0,
                                          lambda: abs(arp_available - get_fdb_dynamic_mac_count(duthost)) < 250),
                               "ARP Table Add failed")
         finally:
@@ -173,7 +175,8 @@ def add_nd(ptfadapter, ip_and_intf_info, ptf_intf_index, nd_available):
         nd_entry_mac = IntToMac(MacToInt(ARP_SRC_MAC) + entry)
         fake_src_addr = generate_global_addr(nd_entry_mac)
         ns_pkt = ipv6_packets_for_test(ip_and_intf_info, nd_entry_mac, fake_src_addr)
-
+        # Add a short delay to avoid packet loss
+        time.sleep(0.01)
         testutils.send_packet(ptfadapter, ptf_intf_index, ns_pkt)
     logger.info("Sending {} ipv6 neighbor entries".format(nd_available))
 
@@ -205,7 +208,7 @@ def test_ipv6_nd(duthost, ptfhost, config_facts, tbinfo, ip_and_intf_info,
                 # The entries we add will not exceed 10000, so the number we tolerate is 100
                 logger.debug("Expected route number: {}, real route number {}"
                              .format(nd_available, get_fdb_dynamic_mac_count(duthost)))
-                pytest_assert(wait_until(20, 1, 0,
+                pytest_assert(wait_until(40, 1, 0,
                                          lambda: abs(nd_available - get_fdb_dynamic_mac_count(duthost)) < 250),
                               "Neighbor Table Add failed")
         finally: