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Overview
Introduction
DLDP C
ONFIGURATION
You may have encountered unidirectional links in networking. When a
unidirectional link occurs, the local device can receive packets from the peer device
through the link layer, but the peer device cannot receive packets from the local
device. Unidirectional link can cause problems such as spanning tree protocol (STP)
loops.
Unidirectional links can be caused by
Fiber cross-connection, as shown in Figure 55
■
Fibers that are not connected or disconnected, as shown in Figure 56, the
■
hollow lines in which refer to fibers that are not connected or disconnected.
Device link detection protocol (DLDP) can detect the link status of an optical fiber
cable or copper twisted pair (such as super category 5 twisted pair). If DLDP finds a
unidirectional link, it disables the related port automatically or prompts you to
disable it manually according to the configurations, to avoid network problems.
Figure 55 Fiber cross-connection
SwitchA
SwitchA
GE2/0/3
GE2/0/3
GE2/0/3
GE2/0/3
SwitchB
SwitchB
PC
PC
GE2/0/4
GE2/0/4
GE2/0/4
GE2/0/4