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Configuration Guide - Reliability

CloudEngine 8800, 7800, 6800, and 5800 V200R003C00

This document describes the configurations of Reliability, including BFD Configuration, VRRP Configuration, DLDP Configuration, Smart Link and Monitor Link Configuration, EFM Configuration, and CFM Configuration.
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DLDP States

DLDP States

The Device Link Detection Protocol (DLDP) allows a device to identify the peer device and check connectivity of the unidirectional link by exchanging DLDP Data Units (DLDPDUs) with the peer device. DLDP defines the following states: Initial, Inactive, Active, Advertisement, Probe, Disable, and DelayDown.

Figure 4-3 State transition during DLDP packet exchange
Table 4-1 DLDP states




DLDP is disabled.


DLDP is enabled but the link is Down.


DLDP is enabled and the link is Up, or neighbor entries are cleared.


All neighbors are bidirectionally reachable or have been in Active state for more than 5 seconds. This is a stable state when no unidirectional link has been detected.


Probe packets are sent to detect whether the link is unidirectional. When an interface enters this state, DLDP starts the probe timer and starts an echo timer for each neighbor to be detected.


DLDP in enhanced mode detects a unidirectional link and disables the interface that fails to send optical signals.


It is a temporary status. When an interface in Active, Advertisement, or Probe state receives a Port-Down event, it enters this state instead of immediately deleting neighbor entries and transiting to the Inactive state. In DelayDown state, the system reserves DLDP neighbor information and only responds to Port-Up events.

Updated: 2019-05-08

Document ID: EDOC1100004359

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