No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


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.
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Overview of DLDP

Overview of DLDP


The Device Link Detection Protocol (DLDP) monitors the link status of optical fibers or copper twisted pairs such as super Category 5 twisted pairs. Upon detecting a unidirectional link on an interface, DLDP automatically shuts down or prompts users to manually shut down the interface. This prevents network faults.


Sometimes unidirectional links occur on networks. On a unidirectional link, the local device can receive packets from the peer device at the link layer, but the peer device cannot receive packets from the local device. Unidirectional links result in problems such as loops on an STP topology.

As shown in Figure 4-1 and Figure 4-2, a unidirectional link fault may be caused by intersected fibers or fiber disconnection.

Figure 4-1 Intersected fibers
Figure 4-2 Fiber disconnection

As a link layer protocol, DLDP works with physical layer protocols to detect the link status. The auto negotiation mechanism at the physical layer detects physical signals and faults, and DLDP identifies the peer device, detects unidirectional links, and shuts down unreachable interfaces. The auto negotiation mechanism and DLDP work together to detect and close unidirectional links at physical and logical layers. If the interfaces on both ends of a link work properly at the physical layer, DLDP checks connections and packet exchange between the two interfaces at the link layer. This detection cannot be implemented using the auto negotiation mechanism.

Updated: 2019-05-08

Document ID: EDOC1100004359

Views: 65898

Downloads: 128

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Previous Next