Dldp Operating Mode - 3Com 4500 Configuration Manual

Timer
Entry aging timer
Enhanced timer
DelayDown timer

DLDP Operating Mode

DLDP can operate in two modes: normal mode and enhanced mode, as described below.
In normal DLDP mode, when an entry timer expires, the device removes the corresponding
neighbor entry and sends an Advertisement packet with RSY tag.
In enhanced DLDP mode, when an entry timer expires, the Enhanced timer is triggered and the
device sends up to eight Probe packets at a frequency of one packet per second to test the
neighbor. If no Echo packet is received from the neighbor when the Echo timer expires, the device
transits to the Disable state.
When a new neighbor joins, a neighbor entry is created and the
corresponding entry aging timer is enabled
When an advertisement packet is received from a neighbor, the
neighbor entry is updated and the corresponding entry aging timer is
updated
In the normal mode, if no packet is received from the neighbor when
the entry aging timer expires, DLDP sends an advertisement packet
with an RSY tag, and deletes the neighbor entry.
In the enhanced mode, if no packet is received from the neighbor
when the entry aging timer expires, DLDP enables the enhanced
timer
The entry aging timer length is three times the advertisement timer
length.
In the enhanced mode, if no packet is received from the neighbor
when the entry aging timer expires, DLDP enables the enhanced
timer for the neighbor. The enhanced timer length is 10 seconds
The enhanced timer then sends one probe packet every second and
eight packets successively to the neighbor.
If no echo packet is received from the neighbor when the enhanced
timer expires, the state of the local end is set to unidirectional
communication state and the state machine turns into the disable
state. DLDP outputs log and tracking information and sends flush
packets. Depending on the user-defined DLDP down mode, DLDP
disables the local port automatically or prompts you to disable the port
manually. Meanwhile, DLDP deletes the neighbor entry.
When a device in the active, advertisement, or probe DLDP state
receives a port down message, it does not removes the
corresponding neighbor immediately, neither does it changes to the
inactive state. Instead, it changes to the delaydown state first.
When a device changes to the delaydown state, the related DLDP
neighbor information remains, and the DelayDown timer is triggered.
The DelayDown timer is configurable and ranges from 1 to 5 seconds.
A device in the delaydown state only responds to port up messages.
A device in the delaydown state resumes its original DLDP state if it
receives a port up message before the delaydown timer expires.
Otherwise, it removes the DLDP neighbor information and changes to
the inactive state.
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Description