The process for an ONU to go online unconfigured involves five states:

- **`O2` Standby:** After receiving the message, the ONU extracts the delimiter value, power level, and pre-allocated compensation delay from the message, and adjusts its configurations accordingly to support subsequent information exchange.

- **`O3` Serial number:** The OLT sends a serial number (SN) request to the ONU. The ONU sends its SN to the OLT. After receiving the SN of the ONU, the OLT allocates a temporary ONU ID to the ONU.

- **`O4` Ranging:** The OLT sends a ranging request to the ONU. After receiving the ranging request from the OLT, the ONU responds with a message carrying its SN and ONU ID. The OLT calculates the compensation delay and sends it to the ONU in a message. After receiving the message, the ONU sets the compensation delay accordingly.

The password is not configured on the OLT. If the automatic discovery function is enabled on the PON port of the OLT, the OLT reports an ONU auto-discovery alarm to the CLI or NMS. The ONU goes online normally only after being confirmed.

It happens when the OLT detects that the ONT is `drunk`, so it tries to update the firmware before opening the GEM link. If this happens, the user has to try changing the software version or other data.

The OMCI standard is defined in a way that suppliers can offer modular and incremental functionality to meet different levels of customer needs.

The standards [^G_988] and [^G_984_4] define the protocol needed to handle all the features of the PON specifications ([^G_984_1], [^G_987], [^G_9807_1], ...), as well as a number of services and functionalities.

The existence of other MEs depends on the architecture and feature set supported by the vendor [^G_988] and [^G_984_4]. Major ISPs and vendors have created their own extensions for MIBs [^att_open_omci], [^verizon_open_omci].

Each MEs consists of an entry ID and zero, one or more instances. Each instance has its own ID, usually starting at 0, but this is not always the case. Every instance has one or more attributes, each characterised by and ID, size and content.

The various MEs are often interrelated. Clause 8.2 of [^G_988] and [^G_984_4] shows the relationship graphs between the various MEs.

In each of the 2 cases the various MEs can be: (R), (W). Only for ME auto-instantiated by the ONT there is also (R, W) while only for ME auto-instantiated by the OLT there are also (R, Set-by-create), (W, Set-by-create), or (R, W, Set-by-create).

* RTL9602/RTL9603 series (for router with integrated PON)

ONTs are the terminating elements of the PON network, and play, like the ONT an essential role in the PON architecture. The ONT converts the optical media into an electrical interface and takes care of authenticating, monitoring, processing as well as managing all matters related to the GPON tree. Often these devices are installed directly in the home[^hsgp_hg_sfu].

The ONT can connect to various terminal devices, such as set-top boxes, wireless routers, TVs, etc., and performs photoelectric conversion, maintenance and monitoring functions. According to the application, ONT can be divided into six types, namely[^hsgp_hg_sfu]:

However, only SFU (Single Family Unit) ONT and HGU (Home Gateway Unit) ONT are used by the end-users in practical application.

HGU ONT, is a home gateway with an uplink interface of the PON, is designed for the single home unit. HGU ONT integrates the functions of ONT and RG to realize more complex control and management and provide Ethernet / IP service, VoIP service, routing mode (firewall and NAT), and optional CATV service. HGU ONT has an Ethernet interface and POTS interface, WLAN interface, USB interface, CATV RF interface are also available. The HGU is a Layer III device[^hsgp_hg_sfu].

The ONT SFU type can be understood as a simple Layer II device, like an L2 switch or media converter, have a single port and are exclusively optical-electric converters. That simply transparently transports traffic from the PON to the eth port(s) of the customer ONT. No routing or VoIP functionality is assumed for the SFU type. For SFU, a simple service configuration from the OLT station is used. The cost of SFU device is cheaper, because additional services (routing, telephony, TV) are not implemented.

Within the GPON OMCI standards we can find two types of interfaces, and they are relatively VEIP and PPTP. This virtual interface are the boundaries between the GPON/OMCI part and the non-GPON/Ethernet part[^G_984_4],[^G_988],[^hsgp_hg_sfu].

ONT will report VEIP or PPTP (Physical Path Termination Point) when MIB 11 oe 329 is uploaded according to the type of the device. Only one VEIP is allowed in a HGU and VEIP is not available for SFU devices. OLT determines the ONT type based on the ONT Type attribute in ME Capability.

PPTP/EthUni, on the other hand, is designed for transparent L2 bridges, potentially N each with its own VLAN. OLT is responsible to provision of VLAN and LAN Port[^nanomad_fc],[^anime_rtl960x].

The SFU type ONT device is configured and controlled completely remotely from the OLT via the OMCI management interface. Generally these devices do not require special configurations and therefore access to the web interface of the client ONT device is not required, although it is possible to update the software. To configure the switching of the required VLANs, the Ethernet port profiles of the client ONT are created at the OLT. Most of user-side configurations must be made in the devices connected to the SFU.

For OMCI data flow, there is a mutually unambiguous mapping between the GEM port on the OLT side with the UNI Ethernet port on the terminal side of the ONT. All data packets can pass through without learning or forwarding the MAC address. The SFU ONT supports multiple VLAN function through bridge mode.

VEIP is a service profile designed to terminate the connection directly on the CPE, providing N services (voice, data, video) each with its own characteristics. Allows multiple Ethernet services to be carried over a single PON link. VEIP virtualises all interfaces of the ONU.

Similarly, all UNI-side modules within a VEIP are invisible to and cannot be managed by the OMCI or the user. They are only visible and manageable to a management domain other than OMCI. In addition, each ONT must have only one VEIP.

In some countries, it is also used to allow quick switches between ISPs, ISP A is assigned Ethernet port 1 of the HGU, ISP B is assigned Ethernet port 2 of the HGU, and so on[^nanomad_fc],[^anime_rtl960x],[^huawei_veip].

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This can be done easily via web ui. If you prefer to do it via the shell use: