Command Manual - STP
Quidway S3500 Series Ethernet Switches
Chapter 1 MSTP Configuration Commands
Huawei Technologies Proprietary
1-32
As a general rule, the switch deletes the corresponding entries in the MAC address
table and ARP table upon receiving TC-BPDU packets. When under malicious attacks
of TC-BPDU packets, the switch shall receive a great number of TC-BPDU packets in a
very short period. Too frequent delete operations shall consume huge switch sources
and bring great risk to network stability.
When the protection from TC-BPDU packet attack is enabled, the switch just perform
one delete operation in a specified period after receiving TC-BPDU packets, as well as
monitoring whether it receives TC-BPDU packets during this period. Even if it detects a
TC-BPDU packet is received in a period shorter than the specified interval, the switch
shall not run the delete operation till the specified interval is reached. This can avoid
frequent delete operations to the MAC address table and ARP table.
Example
# Enable TC-BPDU protection on the switch.
[Quidway] stp tc-protection enable
1.1.35 stp timer forward-delay
Syntax
stp timer forward-delay
centi-senconds
undo stp
timer forward-delay
View
System view
Parameter
centi-senconds
: Specifies Forward Delay, ranging from 400 to 3000 and measured in
centiseconds. By default, the Forward Delay of the switch is 1500 centiseconds.
Description
Using
stp timer forward-delay
command, you can configure Forward Delay for the
switch. Using
undo stp timer forward-delay
command, you can restore the default
Forward Delay .
To avoid temporary loop, MSTP defines a medium state, Learning, when the port
switches from the Discarding state to Forwarding state. There is also a delay before
state switchover to guarantee the synchronous switchover with the remote switch. The
Forward Delay configured on the root bridge determines the state transition time.
The root bridge will determine the state transition time according to the configured
values, while the other switches will apply the forward delay configured on it.
When configuring Hello time, Forward Delay and Max Age, please guarantee the
following equations: