Figure 20: Failed Condition; Figure 21: Failed Condition - Switching At A - Alcatel-Lucent 7450 Manual

MPLS-TP Maintenance Identifiers
In normal condition, user data packets are sent on the working path on both directions, from A to Z
and Z to A.
A defect in the direction of transmission from node Z to node A impacts the working connection
Z-to-A, and initiates the detection of a defect at the node A.
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A
Working
Protection
Selector
Bridge
Working
Protection
Selector
Detected Alarm

Figure 20: Failed Condition

A
Working
1
Protection
APS-1
Selector
Bridge
Working
1
Protection
Selector

Figure 21: Failed Condition - Switching at A

Z
Selector
Selector
Bridge
al_0234
Z
Selector
Selector
Bridge
al_0235
7450 ESS MPLS Guide