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During the Rerouting in the ASON Network, the Protection Switching Time May Exceed the Specification Value If the Optical Power Is Adjusted Improperly

Publication Date:  2012-08-12 Views:  109 Downloads:  0
Issue Description

In the networking scenario with the WSS or WSD board, the protection switching time may exceed the specification value if the optical power is adjusted improperly. 


For example, in the previous ASON networking, The current route is marked in pink and the NS2 board is configured with SNCP protection. Reset the FIU board, and ASON reroutes to the orange path. If the optical power is improperly adjusted at downstream nodes, the switching time of the SNCP protection group may exceed the specification value. 

Alarm Information
Handling Process
As shown in tests, when the original input optical power of the NS2 board is lower, the switching performance in the route break-off of the WSD board is better. During the network design, the optical power of every section must be adjusted strictly in line with the engineering instructions to ensure that the input optical power of the OTU board falls in a proper range (at the middle or lower level between the high threshold and the low threshold). So the protection switching time does not exceed the specification value. 
Root Cause

According to the specification provided by component manufacturers, to set considerable attenuation of the 1x9 WSS 100G module of JDSU used on the WSS or WSD board is a slow process, not a dramatic drop to the target optical power. The following is the specification provided by component manufacturers: 


During the rerouting in the ASON network, the WSD board sets the break-off of the current intra-board route first and then sets a new intra-board route. After the break-off of the current intra-board is set, the NS2 board cannot immediately detect LOS and trigger switching if the input optical power of the NS2 board is close to LOS, because to set the break-off of routes is a slow process. In this case, certain bit errors may occur, as indicated by the meter of testing the protection switching time. As a result, the switching time easily exceeds the specification value.