Fix: LAG counters, if LAG don't have L3 interface

[mad4321]

- What I did
A KeyError exception raised in rfc1213.py if LAG port don't have L3 interface

Oct 25 14:10:29.864852 sonic ERR snmp#snmp-subagent [ax_interface] ERROR: SubtreeMIBEntry.__call__() caught an unexpected exception during _callable_.__call__()
#012Traceback (most recent call last):
#012  File "/usr/local/lib/python3.7/dist-packages/ax_interface/mib.py", line 194, in __call__
#012    return self._callable_.__call__(sub_id, *self._callable_args)
#012  File "/usr/local/lib/python3.7/dist-packages/sonic_ax_impl/mibs/ietf/rfc1213.py", line 413, in get_counter
#012    sai_lag_rif_id = self.port_rif_map[sai_lag_id]#012KeyError: '20000000007c2'

- How I did it
Checked if sai_lag_id is contained in port_rif_map

- How to verify it
Build docker-snmp. No exception is observed.

- Description for the changelog

[qiluo-msft]

@raphaelt-nvidia @stepanblyschak Could you also review?

[raphaelt-nvidia]

Could you please add an explanation, similar to the example above this code, describing the scenario in which the condition you added is required? In other words, how the tables would look different if the LAG has no L3 interface?

[mad4321]

For example configuration with vlan trunk on PortChannel

#show vlan br
+-----------+----------------+--------------+----------------+-------------+-----------------------+
|   VLAN ID | IP Address     | Ports        | Port Tagging   | Proxy ARP   | DHCP Helper Address   |
+===========+================+==============+================+=============+=======================+
|      3103 | 10.112.33.2/29 | PortChannel0 | tagged         | disabled    |                       |
+-----------+----------------+--------------+----------------+-------------+-----------------------+
|      3104 | 10.112.34.2/29 | PortChannel0 | tagged         | disabled    |                       |
+-----------+----------------+--------------+----------------+-------------+-----------------------+

#show ip int
Interface    Master    IPv4 address/mask    Admin/Oper    BGP Neighbor    Neighbor IP
-----------  --------  -------------------  ------------  --------------  -------------
Loopback0              10.111.0.101/32      up/up         N/A             N/A
Vlan3103               10.112.33.2/29       up/up         N/A             N/A
Vlan3104               10.112.34.2/29       up/up         N/A             N/A

ASIC_DB

{
  "ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE:oid:0x60000000008ac": {
     "SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID": "oid:0x3000000000022",
     "SAI_ROUTER_INTERFACE_ATTR_TYPE": "SAI_ROUTER_INTERFACE_TYPE_LOOPBACK",
     "SAI_ROUTER_INTERFACE_ATTR_MTU": "9100"
  },
  
  "ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE:oid:0x6000000000893": {
     "SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID": "oid:0x3000000000022",
     "SAI_ROUTER_INTERFACE_ATTR_SRC_MAC_ADDRESS": "00:E0:EC:E4:80:2E",
     "SAI_ROUTER_INTERFACE_ATTR_TYPE": "SAI_ROUTER_INTERFACE_TYPE_VLAN",
     "SAI_ROUTER_INTERFACE_ATTR_VLAN_ID": "oid:0x26000000000876",
     "SAI_ROUTER_INTERFACE_ATTR_MTU": "9100",
     "SAI_ROUTER_INTERFACE_ATTR_NAT_ZONE_ID": "0"
  },
  
  "ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE:oid:0x60000000005ad": {
    "SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID": "oid:0x3000000000022",
    "SAI_ROUTER_INTERFACE_ATTR_TYPE": "SAI_ROUTER_INTERFACE_TYPE_LOOPBACK",
    "SAI_ROUTER_INTERFACE_ATTR_MTU": "9100"
  },
  
  "ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE:oid:0x6000000000892": {
    "SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID": "oid:0x3000000000022",
    "SAI_ROUTER_INTERFACE_ATTR_SRC_MAC_ADDRESS": "00:E0:EC:E4:80:2E",
    "SAI_ROUTER_INTERFACE_ATTR_TYPE": "SAI_ROUTER_INTERFACE_TYPE_VLAN",
    "SAI_ROUTER_INTERFACE_ATTR_VLAN_ID": "oid:0x26000000000875",
    "SAI_ROUTER_INTERFACE_ATTR_MTU": "9100",
    "SAI_ROUTER_INTERFACE_ATTR_NAT_ZONE_ID": "0"
  },

  "ASIC_STATE:SAI_OBJECT_TYPE_LAG_MEMBER:oid:0x1b00000000086a": {
    "SAI_LAG_MEMBER_ATTR_LAG_ID": "oid:0x2000000000868",
    "SAI_LAG_MEMBER_ATTR_PORT_ID": "oid:0x10000000006ef",
    "SAI_LAG_MEMBER_ATTR_EGRESS_DISABLE": "false",
    "SAI_LAG_MEMBER_ATTR_INGRESS_DISABLE": "false"
  },
 
  "ASIC_STATE:SAI_OBJECT_TYPE_LAG_MEMBER:oid:0x1b00000000086c": {
    "SAI_LAG_MEMBER_ATTR_LAG_ID": "oid:0x2000000000868",
    "SAI_LAG_MEMBER_ATTR_PORT_ID": "oid:0x10000000007ea",
    "SAI_LAG_MEMBER_ATTR_EGRESS_DISABLE": "false",
    "SAI_LAG_MEMBER_ATTR_INGRESS_DISABLE": "false"
  },

  "ASIC_STATE:SAI_OBJECT_TYPE_LAG:oid:0x2000000000868": {
    "NULL": "NULL"
  }
}  

No entries in ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE
with SAI_ROUTER_INTERFACE_ATTR_PORT_ID: oid:0x2000000000868

COUNTERS_DB

{
  "COUNTERS_RIF_TYPE_MAP": {
    "oid:0x6000000000892": "SAI_ROUTER_INTERFACE_TYPE_VLAN",
    "oid:0x6000000000893": "SAI_ROUTER_INTERFACE_TYPE_VLAN",
  },

  "COUNTERS_RIF_NAME_MAP": {
    "Vlan3103": "oid:0x6000000000892",
    "Vlan3104": "oid:0x6000000000893"
  },

  "COUNTERS_LAG_NAME_MAP": {
    "PortChannel0": "oid:0x2000000000868"
  }
}

No entries in COUNTERS_RIF_NAME_MAP/COUNTERS_RIF_TYPE_MAP for PortChannel interface

[raphaelt-nvidia]

I guess that's a bit much to put in code comments. Thanks, LGTM.