Chapter 1 Mstp Configuration; Mstp Overview; Mstp Protocol Data Unit - H3C S7500 Series Operation Manual

Operation Manual – MSTP
H3C S7500 Series Ethernet Switches

Chapter 1 MSTP Configuration

When configuring MSTP, go to these sections for information you are interested in:

MSTP Overview

Root Bridge Configuration
Leaf Node Configuration
The mCheck Configuration
Guard Function Configuration
Digest Snooping Configuration
Rapid Transition Configuration
VLAN-VPN Tunnel Configuration
Displaying and Debugging MSTP
MSTP Configuration Example
VLAN-VPN Tunnel Configuration Example
1.1 MSTP Overview
Spanning tree protocol (STP) cannot enable Ethernet ports to transit their states rapidly.
It costs two times of the forward delay for a port to transit to the forwarding state even if
the port is on a point-to-point link or the port is an edge port. This slows down the
spanning tree convergence of STP.
Rapid spanning tree protocol (RSTP) enables the spanning tree to converge rapidly,
but it suffers from the same drawback as that of STP: all bridges in a LAN share one
spanning tree; packets of all VLANs are forwarded along the same spanning tree, and
therefore redundant links cannot be blocked based on VLANs.
As well as the above two protocols, multiple spanning tree protocol (MSTP) can
disbranch a loop network to form a tree-topological loop-free network to prevent
packets from being duplicated and forwarded endlessly in the loop network. Besides
this, MSTP can also provide multiple redundant paths for packet forwarding and
implement VLAN-based load balancing.
MSTP is compatible with both STP and RSTP. It overcomes the drawbacks of STP and
RSTP. It not only enables spanning trees to converge rapidly, but also enables packets
of different VLANs to be forwarded along their respective paths to provide a better
load-balancing mechanism with redundant links.

1.1.1 MSTP Protocol Data Unit

Bridge protocol data unit (BPDU) is the protocol data unit (PDU) that STP and RSTP
use.
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Chapter 1 MSTP Configuration