3Com Switch 7750 Configuration Guide Guide

DLDP Overview 201
DLDP timers
DLDP works with the following timers:
Delaydown
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.
Table 128 DLDP timers
Timer Description
Advertisement sending timer
Interval of sending advertisement packets, which can be
configured with a command line.
By default, the interval is 10 seconds.
Probe sending timer
The interval is 1 second. In probe status, DLDP sends two
probe packets every second.
Echo waiting timer
It is enabled when DLDP enters probe status. The timeout
time is 10 seconds.
If no echo packet is received from the neighbor when the
Echo waiting timer expires, the local end is set to
unidirectional communication status and the state machine
turns into disable status. DLDP outputs log and tracking
information, sends flush packets. Depending on the
user-defined DLDP down mode, DLDP disables the local port
automatically or prompt the user to disable the port
manually. At the same time, DLDP deletes the neighbor
entry.
Entry aging timer
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 normal mode, if no packet is received from the neighbor
when the entry aging timer expires, DLDP sends an
advertisement packet with RSY tag, and deletes the neighbor
entry.
In enhanced mode, if no packet is received from the
neighbor when the entry aging timer expires, DLDP enables
the enhanced timer.
The interval set for the entry aging timer is three times of that
for the advertisement timer.
Table 127 DLDP status
Status Description