Spanning Tree Protocol Parameters
Several configuration parameters control the operation of the Spanning Tree Protocol. Table
You can cause serious network performance degradation if you do not fully understand Spanning Tree concepts. Be sure to consult personnel experienced with this process prior to configuring Spanning Tree parameters.
Table A-1. Spanning Tree Protocol Defaults
Parameter | Description |
|
| Default Value |
|
|
| ||
Bridge Group | Unique MAC group address, recognized by all bridg- |
| ||
Address | es in the network. |
|
| |
Bridge Identi- | Identifier for each bridge. This parameter consists of | 32768 (bridge | ||
fier | two parts: a | priority) | ||
| adapter address. Ports are numbered in absolute |
| ||
| numbers starting from 1 regardless of their bridge at- |
| ||
| tachment. The network adapter address is the same |
| ||
| address as the first port of the bridge. |
| ||
Port Identifier | Port Identifier Identifies each port of each bridge, with |
| ||
| an incremental default value given for each port. |
| ||
| Port 1 | Port 9 | Port 17 |
|
| Port 2 | Port 10 | Port 18 |
|
| Port 3 | Port 11 | Port 19 |
|
| Port 4 | Port 12 | Port 20 |
|
| Port 5 | Port 13 | Port 21 |
|
| Port 6 | Port 14 | Port 22 |
|
| Port 7 | Port 15 | Port 23 |
|
| Port 8 | Port 16 | Port 24 |
|
Port Priority | Indicates the priority of a specific port in relation to | 128 | ||
| other ports. |
|
|
|
Cost Compo- | The Spanning Tree Protocol calculates and ensures | 19 | ||
nent of Each | that an active topology generates minimal cost paths. |
| ||
Port | A value of 100 is generally used for 10Mbps Ethernet |
| ||
| networks, a value of 19 for 100Mbps Fast Ethernet, |
| ||
| and a value of 4 for 1000Mbps Gigabit Ethernet. |
| ||
For detailed information on the operation of the Spanning Tree Protocol, consult Section 4 of IEEE Standard 802.1D, ISO/IEC 10038:1993.
| Spanning Tree Concepts 87 |
