During the Rerouting in the ASON Network, the Protection Switching Time May Exceed the Specification Value

By | August 26, 2016

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.

WSS

WSS

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

Null

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 1×9 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:

WSD

WSD

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.

Suggestions

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