3Com 5500-EI Series, Справочное руководство

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When DLDP works in normal mode, the system can identify only the unidirectional link caused by
fiber cross-connection.
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When the DLDP protocol 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 broken. To detect unidirectional links that are of the latter type, you
need to configure the ports to operate at specific speed and in full duplex mode. Otherwise, DLDP
cannot take effect.
Examples
# Configure DLDP to work in enhanced mode.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] dldp work-mode enhance
dldp delaydown-timer
Syntax
dldp delaydown-timer delaydown-time
undo dldp delaydown-timer
View
System view
Parameters
delaydown-time : Delaydown timer to be set (in seconds). This argument ranges from 1 to 5.
Description
Use the dldp delaydown-timer command to set the delaydown timer.
Use the undo dldp delaydown-timer command to restore the default delaydown timer setting.
By default, the DelayDown timer is set to 1 second. A period of 5 seconds is recommended.
When a device in the active, advertisement, or probe DLDP state receives a port down message, it
does not remove the corresponding neighbor immediately, nor does it transit to the inactive state.
Instead, it transits to the delaydown state and starts the DelayDown timer. In delaydown state, the
device retains the related DLDP neighbor information. When the DelayDown timer expires, the DLDP
neighbor information is removed.