Which of the following items are optional items for the commissioning between microwave stations?

NE1\NE2\NE3 forms a chain network. There are VC4 other services between NE1 and NE3. NE2 is a pass-through site. After the configuration is completed, NE3 site reports the HP-SLM alarm of C2 byte mismatch.
What are the detection points at this time? (multiple choice)

The SNCP ring network composed of OptiX OSN 3500 equipment uses GXCSA as the cross-connect board, and the main ring is equipped with an SL64 single board. A and B are two adjacent nodes.
The station B receives a large number of errors in the regeneration section and multiplex section on the SL64 board of station A.
At the same time, station A receives the remote error code of the multiplex section reported on the SL64 board of station E.
In the networking diagram, it is found that the distance between A and B is 100km, the rate is 10G, and the configuration structure is "light board + BA + PA + DCU + light board".
Which of the following causes the error code to occur? (multiple choice)

An operator needs to configure 60 clients, 200 OptiX PTN 1900, 100 OptiX OSN 3800 (With ASON), 150 NE40E, 200 CX600 series equipment, and the access side is equipped with FTTx OLT and MDU, a total of 80,000 xDSL lines , 70,000 lines of PSTN ports, 30 OLTs and 300 MDU devices are deployed.
Regarding the description of this network, the error is:

For ODUk ring network protection, the following statement is wrong: