3Com Switch 7754, Configuration Manual

Page: 215 / 940

DLDP Fundamentals 215
DLDP Status A link can be in one of these DLDP states: initial, inactive, active, advertisement,
probe, disable, and delaydown.
DLDP Timers
Table 145 Processing procedure when no echo packet is received from the neighbor
No echo packet received from the neighbor Processing procedure
In normal mode, no echo packet is received when
the echo waiting timer expires. 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.
In enhanced mode, no echo packet is received
when the enhanced timer expires
Table 146 DLDP status
Status Description
Initial Initial status before DLDP is enabled.
Inactive DLDP is enabled but the corresponding link is down
Active DLDP is enabled, and the link is up or an neighbor entry is cleared
Advertisement 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
Probe 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.
Disable 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.
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.
After the DelayDown timer expires, the DLDP neighbor information is
removed.
Table 147 DLDP timers
Timer Description
Advertisement sending timer Interval between sending advertisement
packets, which can be configured on a
command line interface.
By default, the timer length is 5 seconds.
Probe sending timer The interval is 0.5 seconds. In the probe
state, DLDP sends two probe packets in a
second.