H3C Technologies H3C SecPath F1000-E - Manual (Page 98)

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Item Description
Timer
Forward Delay
Set the delay for the root and
designated ports to transit to the
forwarding state.
The length of the forward delay time is
related to the network diameter of the
switched network. The larger the
network diameter is, the longer the
forward delay time should be. If the
forward delay setting is too small,
temporary redundant paths may be
introduced. If the forward delay setting
is too big, it may take a long time for
the network to converge. H3C
recommends that you use the default
setting.
IMPORTANT:
• The settings of hello time,
forward delay and max
age must meet a certain
formula. Otherwise, the
network topology will not
be stable. H3C
recommends you to set the
network diameter and
then have the device
calculate the forward
delay, hello time, and
max age automatically.
• You cannot configure both
the network diameter and
timers.
Hello Time
Hello time is the interval at which the
device sends hello packets to the
surrounding devices to make sure that
the paths are fault-free.
An appropriate hello time setting
enables the device to timely detect link
failures on the network without using
excessive network resources. If the
hello time is set too long, the device
will take packet loss as a link failure
and trigger a new spanning tree
calculation process. If the hello time is
set too short, the device will send
repeated configuration BPDUs
frequently, which adds to the device
burden and causes waste of network
resources. H3C recommends that you
use the default setting.
Max Age
Max age determines how long a
configuration BPDU can be held by the
device.
If the max age time setting is too small,
the network devices will frequently
launch spanning tree calculations and
may take network congestion as a link
failure. If the max age setting is too
large, the network may fail to timely
detect link failures and fail to timely
launch spanning tree calculations,
reducing the auto-sensing capability of
the network. H3C recommends that
you use the default setting.