Which of the following statements about the management plane data Communications Network (DCN) is correct?

The management-plane Data Communications Network (DCN) is an out-of-band, usually Ethernet-based, network whose sole purpose is to give the Operations/Element Management System a path to every network element (NE). Each NE has a dedicated management (craft/OOB) port that attaches directly to the DCN switch or router; DCN traffic is not transported through other NEs and is not carried in-band with user traffic. Therefore, the only statement that accurately reflects DCN operation is that it “can be connected to each NE directly.”

A. DCN is defined as out-of-band; it deliberately avoids using in-band user-traffic channels.
B. DCN reaches the OSS, not the other way round; “OSS/OBS interface” is not a DCN physical port on NEs.
D. DCN packets are not forwarded between NEs; it is a star/hierarchical management network, not an NE-to-NE communications path.

1. Nokia SR OS 22.10.R1 System Management Guide, “Management Ethernet Interface and DCN,” §9.1, pp. 137-138.

2. Nokia 1830 PSS R11.12 Network Management Guide, “2.1.1 Out-of-Band DCN,” pp. 34-35.

3. ITU-T G.7712/Y.1703 (2019), “6.2 DCN architecture: direct NE connectivity,” pp. 8-9.