3Com 7757 Configuration Manual page 215

Table 145 Processing procedure when no echo packet is received from the neighbor
No echo packet received from the neighbor
In normal mode, no echo packet is received when
the echo waiting timer expires.
In enhanced mode, no echo packet is received
when the enhanced timer expires
DLDP Status A link can be in one of these DLDP states: initial, inactive, active, advertisement,
probe, disable, and delaydown.
Table 146 DLDP status
Status
Initial
Inactive
Active
Advertisement
Probe
Disable
DelayDown
DLDP Timers
Table 147 DLDP timers
Timer
Advertisement sending timer
Probe sending timer
Processing procedure
DLDP switches to the disable state,
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.
DLDP sends RSY messages and removes
the corresponding neighbor entries.
Description
Initial status before DLDP is enabled.
DLDP is enabled but the corresponding link is down
DLDP is enabled, and the link is up or an neighbor entry is cleared
All neighbors communicate normally in both directions, or DLDP
remains in active state for more than five seconds and enters this
status. It is a stable state where no unidirectional link is found
DHCP sends packets to check whether the link is a unidirectional. It
enables the probe sending timer and an echo waiting timer for each
target neighbor.
DLDP detects a unidirectional link, or finds (in enhanced mode) that a
neighbor disappears. In this case, DLDP sends and receives only
recover probe packets and recover echo packets.
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.
After the DelayDown timer expires, the DLDP neighbor information is
removed.
Description
Interval between sending advertisement
packets, which can be configured on a
command line interface.
By default, the timer length is 5 seconds.
The interval is 0.5 seconds. In the probe
state, DLDP sends two probe packets in a
second.
DLDP Fundamentals 215