H3C Technologies H3C WX3000 Series Unified Switches - Manual (Page 156)

20-3
Status Description
Probe
DHCP sends packets to check if it is a unidirectional link. 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 does not receive or send DLDP
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.
DLDP timers
DLDP works with the following timers:
Table 20-2 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 5 seconds.
Probe sending timer
The interval is 0.5 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.
Enhanced timer
In 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 timeout time for the enhanced timer is 10 seconds.
The enhanced timer then sends one probe packets every one second
and totally eight packets continuously to the neighbor.
If no echo packet is received from the neighbor when the Enhanced 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, and 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. DLDP
deletes the neighbor entry.