[dualtor]: Add IPv6 only active-active mux support

src/sonic-config-engine/minigraph.py

@@ -2830,13 +2830,14 @@ def get_mux_cable_entries(ports, mux_cable_ports, active_active_ports, neighbors
         neighbor = neighbors[port]['name']
         entry['state'] = 'auto'
 
-        if devices[neighbor]['lo_addr'] is not None:
+        if devices[neighbor]['lo_addr'] is not None or devices[neighbor].get('lo_addr_v6') is not None:
             # Always force a /32 prefix for server IPv4 loopbacks
-            server_ipv4_lo_addr = devices[neighbor]['lo_addr'].split("/")[0]
-            server_ipv4_lo_prefix = ipaddress.ip_network(UNICODE_TYPE(server_ipv4_lo_addr))
-            entry['server_ipv4'] = str(server_ipv4_lo_prefix)
+            if devices[neighbor]['lo_addr'] is not None:
+                server_ipv4_lo_addr = devices[neighbor]['lo_addr'].split("/")[0]
+                server_ipv4_lo_prefix = ipaddress.ip_network(UNICODE_TYPE(server_ipv4_lo_addr))
+                entry['server_ipv4'] = str(server_ipv4_lo_prefix)
 
-            if 'lo_addr_v6' in devices[neighbor] and devices[neighbor]['lo_addr_v6'] is not None:
+            if devices[neighbor].get('lo_addr_v6') is not None:
                 server_ipv6_lo_addr = devices[neighbor]['lo_addr_v6'].split('/')[0]
                 server_ipv6_lo_prefix = ipaddress.ip_network(UNICODE_TYPE(server_ipv6_lo_addr))
                 entry['server_ipv6'] = str(server_ipv6_lo_prefix)
@@ -2847,7 +2848,7 @@ def get_mux_cable_entries(ports, mux_cable_ports, active_active_ports, neighbors
 
             mux_cable_table[port] = entry
         else:
-            print("Warning: no server IPv4 loopback found for {}, skipping mux cable table entry".format(neighbor), file=sys.stderr)
+            print("Warning: no server loopback found for {}, skipping mux cable table entry".format(neighbor), file=sys.stderr)
 
     return mux_cable_table
 

src/sonic-config-engine/tests/test_minigraph_case.py

@@ -445,6 +445,41 @@ def test_minigraph_mux_cable_table(self):
             expected_table
         )
 
+    def test_get_mux_cable_entries_ipv6_only_active_active(self):
+        mux_cable_table = minigraph.get_mux_cable_entries(
+            ports=['Ethernet8'],
+            mux_cable_ports=[],
+            active_active_ports={
+                'Ethernet8': {
+                    'soc_ipv6': 'fc02:1000::3/128'
+                }
+            },
+            neighbors={
+                'Ethernet8': {
+                    'name': 'server01'
+                }
+            },
+            devices={
+                'server01': {
+                    'lo_addr': None,
+                    'lo_addr_v6': 'fc02:1000::2/128'
+                }
+            },
+            redundancy_type='mixed'
+        )
+
+        self.assertEqual(
+            mux_cable_table,
+            {
+                'Ethernet8': {
+                    'state': 'auto',
+                    'server_ipv6': 'fc02:1000::2/128',
+                    'soc_ipv6': 'fc02:1000::3/128',
+                    'cable_type': 'active-active'
+                }
+            }
+        )
+
     def test_dhcp_table(self):
         argument = ['-m', self.sample_graph, '-p', self.port_config, '-v', "DHCP_RELAY"]
         expected = {