TABLE OF CONTENTS In the legacy LAN-PHY based network shown in Fig. 5, the OAM&P functions compatible with SDH/SONET are not provided. Suppose an edge ISP administrates an end-to-end 10GbE LAN-PHY link and an core ISP provides transparent transport service of 10GbE LAN-PHY signal. In this situation, there are several problems.
One is that both ISPs cannot always detect a defect without notification to each other. For example, when a defect occurs at link#1, Edge ISP cannot localize the fault point. The 10GbE standard PCS provides LF/RF (Local Fault/Remote Fault) signaling function. In this case, LF signals are transmitted downstream and LF is detected at Switch #2. RF signals are generated at Switch#2 and transmitted to Switch #1, and RF is detected at Switch #1. Edge ISP can know the defect occurred somewhere in the end-to-end link from link#1 to link#3 but cannot localize where the defect occurred because LF/RF signals do not contain any information other than the defect occurrence. Core ISP cannot detect a defect when it occurred in link#3 or link#4, either. This lack of OAM&P functions makes it difficult to localize the fault point alone.
ILS solves this problem using its SDH/SONET compatible OAM&P functions. The layered bidirectional alarm report functions facilitate the fault localization and make clear who has the responsibility for the fault independently. Table 8 shows relation of fault points and alarm status. In ILS and SDH/SONET, AIS (Alarm Indication Signal) is...
