Dldp Configuration; Dldp Overview; Background - HP A5830 series Configuration Manual

DLDP configuration

DLDP overview

Background

Unidirectional links occur when one end of a link can receive packets from the other end, but the other
end cannot receive packets sent by the first end. Unidirectional links result in 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 via 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. If one of the fibers gets broken, the link becomes a
unidirectional link (one-way link).
There are two types of unidirectional fiber links. One occurs when fibers are cross-connected. The other
occurs when a fiber is not connected at one end, or when one fiber of a fiber pair gets broken.
shows a correct fiber connection and the two types of unidirectional fiber connection.
Figure 9 Correct and incorrect fiber connections
The DLDP detects unidirectional links (fiber links or twisted-pair links) and can be configured to shut
down the related 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
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Figure 9