H3C H3C S5100-SI, Operation Manual, Page: 176 / 830

1-7
Packet type Processing procedure
Creates the neighbor entry if it does not exist on the local
device.
Probe packet
Sends echo packets
containing both
neighbor and its own
information to the
peer
Resets the aging timer of the entry if the neighbor entry
already exists on the local device.
No Drops the echo packet
No Drops the echo packet
Sets the flag bit of the neighbor
to bidirectional link
Echo packet
Checks to
see if the
local device
is in the
probe state
Yes
Checks to
see if the
neighbor
information
contained in
the packet is
the same as
that on the
local device
Yes
If all neighbors are in the
bidirectional link state, DLDP
switches from the probe state to
the advertisement state, and
sets the echo waiting timer to 0.
3) If no echo packet is received from the neighbor, DLDP performs the following processing:
Table 1-7 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.
In enhanced mode, no echo packet is
received when the enhanced 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.
DLDP Neighbor State
A DLDP neighbor can be in one of these two states: two way and unknown. You can check the state of
a DLDP neighbor by using the display dldp command.
Table 1-8 Description on the two DLDP neighbor states
DLDP neighbor state Description
two way The link to the neighbor operates properly.
unknown The device is detecting the neighbor and the neighbor state is unknown.
Link Auto-recovery Mechanism
If the shutdown mode of a port is set to auto shutdown, the port is set to the DLDP down state when
DLDP detects the link connecting to the port is a unidirectional link. A port in DLDP down state does not
forward service packets or receive/send protocol packets except DLDPDUs.
A port in the DLDP down state recovers when the corresponding link recovers. A port in the DLDP down
state sends recover probe packets periodically. On receiving a correct recover echo packet (which