Configuring DLDP
CHAPTERS
3. Appendix: Default Parameters
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This guide applies to: T1500G-8T v2 or above, T1500G-10PS v2 or above, T1500G-10MPS v2 or above, T1500-28PCT v3 or above, T1600G-18TS v2 or above, T1600G-28PS v3 or above, T1600G-28TS v3 or above, T1600G-52TS v3 or above, T1600G-52PS v3 or above, T1700X-16TS v3 or above, T1700G-28TQ v3 or above, T2500G-10TS v2 or above, T2600G-18TS v2 or above, T2600G-28TS v3 or above, T2600G-28MPS v3 or above, T2600G-28SQ v1 or above, T2600G-52TS v3 or above. |
DLDP (Device Link Detection Protocol) is a Layer 2 protocol that enables devices connected through fiber or twisted-pair Ethernet cables to detect whether a unidirectional link exists.
A unidirectional link occurs whenever traffic sent by a local device is received by its peer device but traffic from the peer device is not received by the local device.
Unidirectional links can cause a variety of problems, such as spanning-tree topology loops. Once detecting a unidirectional link, DLDP can shut down the related port automatically or inform users.
Configuration Guidelines
A DLDP-capable port cannot detect a unidirectional link if it is connected to a DLDP-incapable port of another switch.
To detect unidirectional links, make sure DLDP is enabled on both sides of the links.
2.1Using the GUI
Choose the menu MAINTENANCE > DLDP to load the following page.
Figure 2-1 Configure DLDP
Follow these steps to configure DLDP:
1)In the Global Config section, enable DLDP and configure the relevant parameters. Click Apply.
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DLDP State |
Enable or disable DLDP globally. |
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Advertisement Interval |
Configure the interval to send advertisement packets. Valid values are from 1 to 30 seconds, and the default value is 5 seconds. |
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Shut Mode |
Choose how to shut down the port when a unidirectional link is detected: Auto: When a unidirectional link is detected on a port, DLDP will generate logs and traps then shut down the port, and DLDP on this port will change to Disabled. Manual: When a unidirectional link is detected on a port, DLDP will generate logs and traps, and then users can manually shut down the unidirectional link ports. |
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Auto Refresh |
With this option enabled, the switch will automatically refresh the DLDP information. |
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Refresh Interval |
Specify the time interval at which the switch will refresh the DLDP information. Valid values are from 1 to 100 seconds, and the default value is 3 seconds. |
2)In the Port Config section, select one or more ports, enable DLDP and click Apply. Then you can view the relevant DLDP information in the table.
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DLDP |
Enable or disable DLDP on the port. |
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Protocol State |
Displays the DLDP protocol state. Initial: DLDP is disabled. Inactive: DLDP is enabled but the link is down. Active: DLDP is enabled and the link is up, or the neighbor entries in this device are empty. Advertisement: No unidirectional link is detected (the device has established bidirectional links with all its neighbors) or DLDP has remained in an Active status for more than 5 seconds. Probe: In this state, the device will send out Probe packets to detect whether the link is unidirectional. The port enters this state from the Active state if it receives a packet from an unknown neighbor. Disable: A unidirectional link is detected. |
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Link State |
Displays the link state. Link-Down: The link is down. Link-Up: The link is up. |
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Neighbour State |
Displays the neighbour state. Unknown: Link detection is in progress. Unidirectional: The link between the port and the neighbor is unidirectional. Bidirectional: The link between the port and the neighbor is bidirectional. |
2.2Using the CLI
Follow these steps to configure DLDP:
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Step 1 |
configure Enter global configuration mode. |
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Step 2 |
dldp Globally enable DLDP. |
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Step 3 |
dldp interval interval-time Configure the interval of sending advertisement packets on ports that are in the advertisement state. interval-time: Specify the interval time. The valid values are from 1 to 30 seconds. By default, it is 5 seconds. |
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Step 4 |
dldp shut-mode { auto | manual } Configure the DLDP shutdown mode when a unidirectional link is detected. auto: The switch automatically shuts down ports when a unidirectional link is detected. It is the default setting. manual: The switch displays an alert when a unidirectional link is detected. Then the users can manually shut down the unidirectional link ports. |
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Step 5 |
interface {fastEthernet port | range fastEthernet port-list | gigabitEthernet port | range gigabitEthernet port-list | ten-gigabitEthernet port | range ten-gigabitEthernet port-list} Enter interface configuration mode. |
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Step 6 |
dldp Enable DLDP on the specified port. |
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Step 7 |
show dldp Verify the global DLDP configuration. |
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Step 8 |
show dldp interface Verify the DLDP configuration of the ports. |
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Step 9 |
end Return to privileged EXEC mode. |
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Step 10 |
copy running-config startup-config Save the settings in the configuration file. |
The following example shows how to enable DLDP globally, configure the DLDP interval as 10 seconds and specify the shutdown mode as auto.
Switch#configure
Switch(config)#dldp
Switch(config)#dldp interval 10
Switch(config)#dldp shut-mode auto
Switch(config)#show dldp
DLDP Global State: Enable
DLDP Message Interval: 10
DLDP Shut Mode: Auto
Switch(config)#end
Switch#copy running-config startup-config
The following example shows how to enable DLDP on port 1/0/1.
Switch#configure
Switch(config)#interface gigabitEthernet 1/0/1
Switch(config-if)#dldp
Switch(config-if)#show dldp interface
Port DLDP State Protocol State Link State Neighbor State
---- ---------- -------------- ---------- --------------
Gi1/0/1 Enable Inactive Link-Down N/A
Gi1/0/2 Disable Initial Link-Down N/A
...
Switch(config-if)#end
Switch#copy running-config startup-config
Default settings of DLDP are listed in the following table.
Table 3-1Default Settings of DLDP
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Parameter |
Default Setting |
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Global Config |
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DLDP State |
Disabled |
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Advertisement Interval |
5 seconds |
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Shut Mode |
Auto |
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Auto Refresh |
Disabled |
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Refresh Interval |
3 seconds |
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Port Config |
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DLDP |
Disabled |