TP-Link T2500-28TCTL-SL5428E T2500-28TCUN V1 User Guide - Page 139

Table 8-3 DLDP Link State, DLDP Process

Page 139 highlights

State Advertisement Probe Disable Description This state indicates that no unidirectional link is detected, which includes two kinds of situations: 1. This device establishes bidirectional links with all its neighbors. 2. DLDP remains in Active state for more than 5 seconds. A device enters this state from the Active state if it receives a packet from an unknown neighbor. In this state, the device will send out Probe packets to detect whether the link is unidirectional. This state indicates that a unidirectional link is detected. Table 8-3 DLDP Link State 2. DLDP Work Process The general DLDP work process chart is shown below: Figure 8-11 DLDP Process The process is illustrated below: ○1 : When DLDP is enabled on the link in down state, the DLDP link state will transit to Inactive. ○2 : When the DLDP-enabled link is up, the DLDP link state will transit to Active. The device will send out Advertisement packets to the peer device with resynchronization tag in this state. ○3 : If the device doesn't receive any DLDP packets within 5 seconds, the DLDP link state will transit to Advertisement. ○4 : After receiving a packet from an unknown neighbor, the device's link state will transit from Active to Probe, and then send out several probe packets to detect the link state. ○5 : If the device receives echo packets from its peer device, the link state between them will be tagged as bidirectionally linked and the DLDP state will transit from Probe to Advertisement. A device in the Advertisement state will send advertisement packets. ○6 : If the device receives no echo packets after a specified period of time, the link will be tagged as unidirectional and the DLDP state will transit from Probe to Disable. This port will be shut down automatically or manually (depending on the Shut Mode configured). 129

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129
State
Description
Advertisement
This state indicates that no unidirectional link is detected, which includes two
kinds of situations:
1. This device establishes bidirectional links with all its neighbors.
2. DLDP remains in Active state for more than 5 seconds.
Probe
A device enters this state from the Active state if it receives a packet from an
unknown neighbor. In this state, the device will send out Probe packets to
detect whether the link is unidirectional.
Disable
This state indicates that a unidirectional link is detected.
Table 8-3 DLDP Link State
2. DLDP Work Process
The general DLDP work process chart is shown below:
Figure 8-11 DLDP Process
The process is illustrated below:
1
: When DLDP is enabled on the link in down state, the DLDP link state will transit to Inactive.
2 : When the DLDP-enabled link is up, the DLDP link state will transit to Active. The device will
send out Advertisement packets to the peer device with resynchronization tag in this state.
3 : If the device doesn’t receive any DLDP packets within 5 seconds, the DLDP link state will
transit to Advertisement.
4 : After receiving a packet from an unknown neighbor, the device’s link state will transit from
Active to Probe, and then send out several probe packets to detect the link state.
5
: If the device receives echo packets from its peer device, the link state between them will be
tagged as bidirectionally linked and the DLDP state will transit from Probe to Advertisement. A
device in the Advertisement state will send advertisement packets.
6
: If the device receives no echo packets after a specified period of time, the link will be tagged
as unidirectional and the DLDP state will transit from Probe to Disable. This port will be shut down
automatically or manually (depending on the Shut Mode configured).