Huawei Quidway S7700 Configuration Manual - Ethernet page 445

Quidway S7700 Smart Routing Switch
Configuration Guide - Ethernet
1.
2.
3.
4.
According to current networking, master ports and backup ports may be involved. For details,
see
MSTP also supports the following features to meet requirements of special applications and
extended functions:
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Table 9-5 MSTP protection
MSTP
Protection
BPDU
protection
TC protection Generally, after receiving
Issue 01 (2011-07-15)
In a ring network, divide regions and create different instances for regions.
Select a switching device functioning as a root bridge from switching devices for each
instance.
In each instance, calculate the shortest paths from the other switching devices to the root
bridge, and select a root port for each non-root switching device.
In each instance, select a designated port for each connection according to port IDs.
9.1.1 MSTP Introduction.
Supports the Proposal/Agreement mechanism to implement rapid convergence.
Supports protection functions as listed in
Supports MSTP multi-process in the scenario where MSTP and STP/RSTP are used
together. MSTP multi-process implements independent spanning tree calculation for every
access rings.
Supports MSTP interoperability between Huawei devices and non-Huawei devices. Proper
parameters are required on Huawei devices running MSTP to ensure nonstop
communication.
Scenario
An edge port changes to be a
non-edge port after
receiving a BPDU, which
triggers spanning tree
recalculation. If an attacker
keeps sending bogus BPDUs
to a switching device,
network flapping occurs.
TC BPDUs (packets for
advertising network
topology changes), a
switching device needs to
delete MAC entries and ARP
entries. Frequent deletion
operations will exhaust CPU
resources.
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Table 9-5.
Configuration Impact
After BPDU protection is enabled on the
switching device, the switching device shuts
down the edge port if the edge port receives
an RST BPDU, and notifies the NMS of the
shutdown event. The attributes of the edge
port are not changed.
TC protection is used to suppress TC-BPDUs.
The number of times that TC-BPDUs are
processed by a switching device within a
given time period is configurable. If the
number of TC-BPDUs that the switching
device receives within the given time exceeds
the specified threshold, the switching device
handles TC-BPDUs only for the specified
number of times. Excessive TC-BPDUs are
processed by the switching device as a whole
for once after the timeout period expires. This
protects the switching device from frequently
deleting MAC entries and ARP entries, thus
avoiding over-burden.
9 MSTP Configuration
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