H3C Technologies H3C S3100 Series Switches - Manual (Page 199)

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To do … Use the command … Remarks
Set the delaydown timer
dldp delaydown-timer
delaydown-time
Optional
By default, the delaydown
timer expires after 1
second it is triggered.
Set the DLDP handling mode when an
unidirectional link is detected
dldp
unidirectional-shutdown
{ auto | manual } Optional.
By default, the handling
mode is auto.
Set the DLDP operating mode
dldp work-mode
{ enhance | normal }
Optional.
By default, DLDP works in
normal mode.
Note the following when performing basic DLDP configuration.
z DLDP can detect unidirectional links only after the links are connected. Therefore, before enabling
DLDP, make sure that optical fibers or copper twisted pairs are connected.
z To ensure unidirectional links can be detected, make sure DLDP is enabled on both sides; and the
interval for sending advertisement packets, authentication mode, and password are the same on
both sides.
z The interval for sending advertisement packets ranges from 1 to 100 seconds and defaults to 5
seconds. You can adjust this setting as needed to enable DLDP to respond in time to link failures.
If the interval is too long, STP loops may occur before unidirectional links are terminated; if the
interval is too short, network traffic may increase in vain and available bandwidth decreases.
Normally, the interval is shorter than one-third of the STP convergence time, which is generally 30
seconds.
z DLDP does not process any link aggregation control protocol (LACP) event, and treats each link in
the aggregation group as independent.
z When connecting two DLDP-enabled devices, make sure the software running on them is of the
same version. Otherwise, DLDP may operate improperly.
z When you use the dldp enable/dldp disable command in system view to enable/disable DLDP on
all optical ports of the switch, the configuration takes effect on the existing optical ports, instead of
those added subsequently.
z Make sure the authentication mode and password configured on both sides are the same for DLDP
to operate properly.
z When DLDP works in enhanced mode, the system can identify two types of unidirectional links:
one is caused by fiber cross-connection and the other is caused by one fiber being not connected
or being disconnected.
z When DLDP works in normal mode, the system can identify unidirectional links caused by fiber
cross-connection.
z When the device is busy with services and the CPU utilization is high, DLDP may issue mistaken
reports. You are recommended to configure the operating mode of DLDP as manual after
unidirectional links are detected, so as to reduce the influence of mistaken reports.
Resetting DLDP State
You can reset the DLDP state for the ports shut down by DLDP due to unidirectional links to enable
DLDP detection again.