The OID you will use is what information you want to get from Port 1, there isn't a specific OID for that port.
For example:
.1.3.6.1.2.1.2.2.1.2 is the ifDescr OID which shows manufacturer, product name and hardware interface
.1.3.6.1.2.1 is the mib-2 OID which contains the above OID (as you can see the first 6 numbers match) and this contains other ifMIBs that give out information about the device
You should be able to find the OID you need in the MIB you are using for that specific device.