SNMP, MIBs & OIDs

[spj2019]

Hi, 
Someone here wanted to integrate the monitoring of a few Cisco appliances in his dashboard. Better yet, he just wants to provide the situation of the ports belonging to a couple of devices (3650 & 2960) within his application. To do this he uses SNMP GET commands for OIDs=.1.3.6.1.2.1.2.2.1.8.1  thru OID=.1.3.6.1.2.1.2.2.1.8.24. 
Just to make sure I accessed the MIB on the 3650 using an SNMPWALK utility and saw that although the device only has 24 + 4 ports, the OIDs which presumably map to the interfaces are 46 (?)   This number appears strange because I  would have expected a maximum of 52 (or 48 or 28 or 24) to cater for all versions of the device. Are they looking at the wrong OIDs? Where can I find an 'official' MIB for Cisco devices ? 
Thanks for any help / insight. Regards, SPJ 

Further analysis of the MIB confirms the number of interfaces in OID=.1.3.6.1.2.1.2.1.0, Type=Integer, Value=46.
On my 2960 device, the number of interfaces reported are 35 (OID=.1.3.6.1.2.1.2.1.0, Type=Integer, Value=35).
The other thing I don't know how to explain is that beneath the ifOperStatus main node 1.3.6.1.2.1.2.2.1.8, the subsequent OIDs have a weird numbering sequence (i.e. 1.3.6.1.2.1.2.2.1.8.1, 1.3.6.1.2.1.2.2.1.8.901, 1.3.6.1.2.1.2.2.1.8.5179/5180/5181/10101/10102/10103...10128/14001/14002. Any ideas ? 

[spj2019 · Accepted solution]

By analyzing the MIB extracted via an SNMPWALK, we verified that the number of ports (ifNumber - interface reference info -  OID=.1.3.6.1.2.1.2.1.0) includes the virtual interfaces, the stack ports, etc., not only the ethernet switch ports, and that's why it's reported as 46. The order is quite arbitrary though and in the case of the 2960 switch all virtual ports are listed before the ethernet ports. So it appears they'll have to extract the occurrences where the ifDescr (OID = .1.3.6.1.2.1.2.2.1.2) contains the string GigabitEthernet1/0 in it and verify the corresponding occurrence of the operational status (ifOperStatus - OID = .1.3.6.1.2.1.2.2.1.8).  Hope we got it right !