Fix ipCidrRouteStatus for loopback: no need to check route table (son…

…ic-net#60)

* Fix ipCidrRouteStatus for loopback: no need to check route table

Signed-off-by: Qi Luo <qiluo-msft@users.noreply.github.com>

* (comment)

Signed-off-by: Qi Luo <qiluo-msft@users.noreply.github.com>

src/sonic_ax_impl/mibs/ietf/rfc4292.py

@@ -29,7 +29,7 @@ def reinit_data(self):
         if not loopbacks:
             return
 
-        # collect only ipv4 interfaces
+        ## Collect only ipv4 lo interfaces
         for loopback in loopbacks:
             lostr = loopback.decode()
             loip = lostr[len("INTF_TABLE:lo:"):]
@@ -45,6 +45,12 @@ def update_data(self):
         self.route_dest_map = {}
         self.route_dest_list = []
 
+        ## The nexthop for loopbacks should be all zero
+        for loip in self.loips:
+            sub_id = ip2tuple_v4(loip) + (255, 255, 255, 255) + (self.tos,) + (0, 0, 0, 0)
+            self.route_dest_list.append(sub_id)
+            self.route_dest_map[sub_id] = self.loips[loip].packed
+
         self.db_conn.connect(mibs.APPL_DB)
         route_entries = self.db_conn.keys(mibs.APPL_DB, "ROUTE_TABLE:*")
         if not route_entries:
@@ -66,11 +72,6 @@ def update_data(self):
                     sub_id = ip2tuple_v4(ipn.network_address) + ip2tuple_v4(ipn.netmask) + (self.tos,) + ip2tuple_v4(nh)
                     self.route_dest_list.append(sub_id)
                     self.route_dest_map[sub_id] = ipn.network_address.packed
-            elif ipnstr in self.loips:
-                ## Note: ipv4 /32 or ipv6 /128 routes will has no prefix ending
-                sub_id = ip2tuple_v4(ipnstr) + (255, 255, 255, 255) + (self.tos,) + (0, 0, 0, 0)
-                self.route_dest_list.append(sub_id)
-                self.route_dest_map[sub_id] = self.loips[ipnstr].packed
 
         self.route_dest_list.sort()