The transport layer in the OSI model is responsible for end-to-end communication and includes two main protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) .
* IP (Internet Protocol) : Works at the network layer and is responsible for routing packets across networks.
* ARP (Address Resolution Protocol) : Works at the network layer and maps IP addresses to MAC addresses.
* TCP : A connection-oriented protocol at the transport layer that ensures reliable communication through acknowledgments and retransmissions.
* UDP : A connectionless-oriented protocol at the transport layer that provides faster but less reliable communication compared to TCP.
Since the question specifies a connectionless-oriented protocol at the transport layer, the correct answer is UDP .
References:
* HCIA Huawei ACCESS Official Documentation , Chapter: Transport Layer Protocols.
* TCP/IP Protocol Suite Overview by Huawei.

Adding an ONT to the OLT:
Adding an ONT (Optical Network Terminal) to the OLT involves several steps, but the critical step is registering the ONT and binding it to the appropriate profile.
Key Steps:
DBA Profile: Configures dynamic bandwidth allocation for the ONT but is not mandatory during initial registration.
ONT Service Profile: Defines services (e.g., Internet, IPTV) but is applied after the ONT is added.
Add ONT and Bind Profile: Registers the ONT with the OLT and binds it to a pre-configured line profile. This is the essential step for adding an ONT.
ONT Line Profile: Configures the VLAN and service parameters but is created before adding the ONT.
Why C?
The most critical action when adding an ONT is to register it and bind it to a profile, ensuring it is recognized and operational within the network.
Thus, the correct answer is C.