9032785 Spanning Tree Concepts 83
Spanning Tree Protocol Parameters

Several configuration parameters control the operation of the Spanning

Tree Protocol. Table B-1 describes the parameters and lists the

ELS100-24TXM switch default settings for each parameter.

Table B-1. Spanning Tree Protocol Defaults

For detailed information on the operation of the Spanning Tree Protocol,

consult Section 4 of IEEE Standard 802.1D, ISO/IEC 10038:1993.

You can cause serious network performance degradation
if you do not fully understand Spanning Tree concepts.
Be sure to consult personnel experienced with this pro-
cess prior to configuring Spanning Tree parameters.
Parameter Description Default Value
Brid
g
e
Group
Address
Unique MAC
g
roup address, reco
g
nized by all brid
g
es
in the network.
Brid
g
e Iden-
tifier Identifier for each brid
g
e. This parameter consists of
two parts: a 16-bit brid
g
e priority and a 48-bit network
adapter address. Ports are numbered in absolute
numbers startin
g
from 1 re
g
ardless of their brid
g
e
attachment. The network adapter address is the same
address as the first port of the brid
g
e.
32768 (brid
g
e
priority)
Port Identi-
fier Identifies each port of each brid
g
e, with an incremen-
tal default value
g
iven for each port.
Port 1 -32768 Port 9 -32776 Port 17 -32784
Port 2 -32769 Port 10 -32777 Port 18 -32785
Port 3 -32770 Port 11 -32778 Port 19 -32786
Port 4 -32771 Port 12 -32779 Port 20 -32787
Port 5 -32772 Port 13 -32780 Port 21 -32788
Port 6 -32773 Port 14 -32781 Port 22 -32789
Port 7 -32774 Port 15 -32782 Port 23 -32790
Port 8 -32775 Port 16 -32783 Port 24 -32791
Port Priority Indicates the priority of a specific port in relation to
other ports. 128
Cost Compo-
nent of Each
Port
The Spannin
g
Tree Protocol calculates and ensures
that an active topolo
g
y
g
enerates minimal cost paths.
A value of 100 is
g
enerally used for 10Mbps Ethernet
networks and a value of 10 is
g
enerally used for
100Mbps Ethernet networks.
10