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OAM plays an important role in PTN technology. The main function of OAM is check defect before abnormal event.
The bit errors which could be corrected or time deviation could be isolated within a certain range. It dose not disturb
network operation. And therefore, it ensure carrier to fulfill QoS commitment and reach SLA subscription.T-MPLS is
connection-oriented packet transport technology. Connection-oriented means it can provide carrier-level service and
must have equal OAM (Operation, Administration and Maintenance) function of traditional transport network. OAM
mechanism becomes key technology of T-MPLS.
OAM function is very important to telecom network. It's especially import to network which has QoS. OAM could
simplify network operation, check network performance and reduce operation cost.
Firstly, the functional requirements of T-MPLS OAM and MPLS-TP OAM are analyzed. The similarity of T-MPLS
OAM and MPLS-TP OAM is founded. By deep analysis the mechanism of T-MPLS OAM, it shows that the OAM is
import for PTN. Then OAM technique of T-MPLS and MPLS-TP is analyzed in detail. At last, analysis of commonality
is carried out on function types. Domain reference model and nesting-technique shows the consistency of both OAM
functions.
Both of T-MPLS and MPLS-TP introduce OAM nesting. Eight MEG Levels (from 0 to 7) are available to
accommodate different network deployment scenarios. In order to distinguish OAM packets of nested MEGs, each MEP
tunnels incoming OAM packets by incrementing the MEL in the source direction and decrementing it in the sink
direction. Each MEP/MIP generates and processes OAM packets at the MEL=0, while other OAM packets are forwarded
with traffic. It's very simple and high efficiency method.
By comparing the functions of T-MPLS OAM and MPLS-TP OAM, even there are few differences on PTN
implementation detail; the OAM mechanism and framework are basically same. Both of them meet the requirements of
carrier-grade OAM. They has important role in their realization process. As long as posses powerful OAM capability,
PTN has more competitiveness in the future market.
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