Huawei AR530 series Configuration Manual page 245

Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
Port
Role
Backup
port
Master
port
Regional
edge port
Edge port
Issue 01 (2014-11-30)
Description
l From the perspective of sending BPDUs, a backup port is blocked after a
BPDU sent by itself is received.
l From the perspective of user traffic, a backup port provides a backup/
redundant path to a segment where a designated port already connects.
As shown in Figure 7-7, CP3 is a backup port.
A master port is on the shortest path connecting MST regions to the CIST root.
BPDUs of an MST region are sent to the CIST root through the master port.
Master ports are special regional edge ports, functioning as root ports on ISTs
or CISTs and master ports in instances.
As shown in Figure 7-8, S1, S2, S3, and S4 form an MST region. AP1 on S1,
being the nearest port in the region to the CIST root, is the master port.
A regional edge port is located at the edge of an MST region and connects to
another MST region or an SST.
During MSTP calculation, the roles of a regional edge port in the MSTI and the
CIST instance are the same. If the regional edge port is the master port in the
CIST instance, it is the master port in all the MSTIs in the region.
As shown in Figure 7-8, AP1, DP1, and DP2 in an MST region are directly
connected to other regions, and therefore they are all regional edge ports of the
MST region.
AP1 is a master port in the CIST. Therefore, AP1 is the master port in every
MSTI in the MST region.
An edge port is located at the edge of an MST region and does not connect to
any switching device.
Generally, edge ports are directly connected to terminals.
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7 MSTP Configuration
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