l
Protection functions
describes protection functions provided by RSTP.
Table 6-13
Protection functions
Protectio
n
Function
Scenario
Principle
BPDU
protection
On a switching device, ports
directly connected to a user
terminal such as a PC or file
server are edge ports.
Usually, no RST BPDUs are
sent to edge ports. If a
switching device receives
bogus RST BPDUs on an edge
port, the switching device
automatically sets the edge
port to a non-edge port and
performs STP calculation
again. This causes network
flapping.
BPDU protection enables a switching
device to set the state of an edge port to
error-down if the edge port receives an
RST BPDU. In this case, the port remains
the edge port, and the switching device
sends a notification to the NMS.
Root
protection
The root bridge on a network
may receive superior RST
BPDUs due to incorrect
configurations or malicious
attacks. When this occurs, the
root bridge can no longer serve
as the root bridge, causing an
incorrect change of the
network topology. As a result,
traffic may be switched from
high-speed links to low-speed
links, leading to network
congestion.
If root protection is enabled on a
designated port, the port role cannot be
changed. When the designated port
receives a superior RST BPDU, the port
enters the Discarding state and does not
forward packets. If the port does not
receive any superior RST BPDUs within
a period (generally two Forward Delay
periods), the port automatically enters the
Forwarding state.
NOTE
Root protection takes effect only on designated
ports.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
6 STP/RSTP Configuration
Issue 01 (2014-11-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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