Similar to this thread, I wanted to see what VLANs were allowed for a trunked port as reported by SNMP with Python.
With the help of a couple of colleagues, I made some progress.
>>> vlan_value = '000000000020000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000' >>> for key,value in enumerate(format(int(vlan_value, 16), "0100b").rjust(len(vlan_value) * 4, '0')): ... if value == '1': ... print key ... ... ... 42 146
- Convert the string returned to Hex
- Convert that to Binary
- Right fill 0s to the appropriate length to give offset (determined by the size of the string)
- Loop through the resulting value and each character that is a 1 is an enabled VLAN on the port
In conjunction with LLDP, I’m able to query each switch/port and interface is connected to and determine if the VLANs are set properly on the port.