Spanning tree configuration, Stp protocol packets – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
Page 51
42
Spanning tree configuration
As a Layer 2 management protocol, the Spanning Tree Protocol (STP) eliminates Layer 2 loops by
selectively blocking redundant links in a network, and also allows for link redundancy.
Recent versions of STP include the Rapid Spanning Tree Protocol (RSTP), and the Multiple Spanning Tree
Protocol (MSTP).
This chapter includes these sections:
•
•
•
•
•
Spanning tree configuration task list
•
Displaying and maintaining the spanning tree
•
Spanning tree configuration examples
NOTE:
•
The term "switch" or "device" in this chapter refers to the switching engine on a WX3000E wireless
switch.
•
The WX3000E series comprises WX3024E and WX3010E wireless switches.
•
The port numbers in this chapter are for illustration only.
STP
STP was developed based on the 802.1d standard of IEEE to eliminate loops at the data link layer in a
local area network (LAN). Networks often have redundant links as backups in case of failures, but loops
are a very serious problem. Devices running STP detect loops in the network by exchanging information
with one another, and eliminate loops by selectively blocking certain ports to prune the loop structure
into a loop-free tree structure. This avoids proliferation and infinite cycling of packets that would occur in
a loop network and prevents decreased device performance caused by receiving duplicate packets.
In the narrow sense, STP refers to IEEE 802.1d STP. In the broad sense, STP refers to the IEEE 802.1d STP
and various enhanced spanning tree protocols derived from that protocol.
STP protocol packets
STP uses bridge protocol data units (BPDUs), also known as configuration messages, as its protocol
packets.
STP-enabled network devices exchange BPDUs to establish a spanning tree. BPDUs contain sufficient
information for the network devices to complete spanning tree calculation.
STP uses the following types of BPDUs: