Configuring Dldp; Overview - HPE FlexNetwork HSR6800 series Configuration Manual

Configuring DLDP

DLDP is supported only when the SAP module is operating in bridge mode.

Overview

Unidirectional links occur when only one end of a bidirectional link can receive packets.
Unidirectional links cause problems such as loops in an STP-enabled network.
For example, the link between two switches, Switch A and Switch B, is a bidirectional link when they
are connected through a fiber pair, with one fiber used for sending packets from A to B and the other
for sending packets from B to A. This link is a two-way link. When one of the fibers stops working, the
link becomes a unidirectional link (one-way link).
Unidirectional fiber links through the following types:
•
Cross-connected.
•
Disconnected at one end or one fiber of a fiber pair is broken.
Figure 7 shows a correct fiber connection and the two types of unidirectional fiber connections.
Figure 7 Correct and incorrect fiber connections
The device link detection protocol (DLDP) detects unidirectional links (fiber links or twisted-pair links)
and can be configured to shut down the faulty port automatically or prompt users to take actions to
avoid network problems.
As a data link layer protocol, DLDP cooperates with physical layer protocols to monitor link status.
When the auto-negotiation mechanism provided by the physical layer detects physical signals and
faults, DLDP performs operations such as identifying peer devices, detecting unidirectional links,
and shutting down unreachable ports.
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