Rules For Creating The Tree Structure; Bridge Information - Hirschmann PowerMICE User Manual

Rapid Spanning Tree
Port identification
U
The port identification consists of two bytes. One part, the lower-value
byte, reflects a fixed relationship to the physical port number. This part
ensures that no port in a bridge receives the same designation as
another port in the same bridge. The second part contains the priority
number which is set by the management administrator (default:128). It is
also true here that the port with the lowest numerical value for its port
identifier is the one with the highest.
Fig. 3: Port identification

1.1.3 Rules for creating the tree structure

Bridge information

U
In order to compute their tree structures, the bridges need information
about other bridges that are present in the network. This information is
obtained by each bridge sending a BPDU (Bridge Protocol Data Unit) to
all other bridges.
Along with other information, the BPDU contains the
D
bridge identifier,
D
root path costs, and
D
port identification
(see IEEE 802.1D).
Redundancy L3P
Release 3.0 01/07
MSB LSB
Priority Port number
1.1 The Spanning Tree Protocol
17