• 1.  STP port priority

    Posted 01-23-2021 02:02
    Hello everyone.

    From observing transmitted BPDUs, I've noticed that Junos switches increment advertised port priorities by 1.

    For example, if I leave port priorities alone, they are set to the default value of 128 i.e. 0x80.  When I observe the BPDU via RSTP traceoptions, I see that the advertise port priority is 129 i.e. 0x81. 

    I see the same incrementing behaviour when I configure non-default port priority values.

    Why is Junos adding 1 to the configured port priority?