PPPOE is a point-to-point protocol (PPP) encapsulated in Ethernet in the framework of a tunnel network protocol due to integrate the PPP protocol, so the traditional Ethernet is unable to provide authentication encryption and compression, and other functions, can also be used for cable modem and digital subscriber line to Ethernet protocol to provide user access system.

Multicast technology is designed in the IP network, in the form of a “best” to send information to a particular target group, the target group is called a multicast group. When active host send information demand to the target host, the source host just send a copy of the data, the data of the destination address is a multicast group address.In this way, all belong to the group members can receive a copy of the original host data, the multicast mode members who really need information will receive information,while others can’t receive it.Therefore, multicast method solves the duplication of data and bandwidth in unicast, and also solves the waste of bandwidth in multicast method.

SNMP means simple network management protocol, which is a standard protocol specially designed for IP network management network nodes, such as servers, workstations, routers, switches, etc. It is an application layer protocol.SNMP protocol enables network administrators to manage network performance, discover and solve network problems, and plan network growth. SNMP consists of three key components: network management system, managed device, and agent.

DHCP(Dynamic host configuration protocol), is a LAN network protocol that works using the UDP protocol.DHCP can help us assign IP addresses and related IP information to computers in the network.DHCP can also configure the correct subnet mask, default gateway, and DNS server information on the device.

The main difference between GPON and EPON is the use of completely different standards.GPON was defined by ITU-TG.984 and EPON was defined by IEEE802.3ah.In application,GPON has a bigger bandwidth than EPON, its business carrying more efficient, spectral ability stronger, can transmit more bandwidth business, achieve more users access, pay more attention to business and QoS guarantee, but more complex, so cost is higher than its relative EPON , but with the large-scale deployment of GPON technology, EPON and GPON is diminishing cost differences.

For epon it’s normal optical receiving power between -3dbm to -27dbm

For gpon it’s normal optical receiving power between -8dbm to -28dbm

SFU (Single Family Unit) single-family unit ONU

It is mainly used for single home users in FTTH scenarios and ordinary terminals that only support broadband access. Generally, it has 1 to 4 Ethernet interfaces and provides Ethernet / IP services. The built-in optical equipment or IAD equipment can support CATV services or VoIP business. Now often used in conjunction with home routers to provide greater business capabilities.

HGU (Home Gateway Unit) Home gateway unit type ONU

It is mainly used for single home users in FTTH occasions. Compared with SFU, which has the function of home gateway, it is equivalent to a home gateway with PON uplink interface. It generally has 2 ~ 4 Ethernet interfaces, 1 WLAN interface and 1 USB interface. Provide Ethernet / IP services, through the built-in optical or IAD devices can support CATV business or VoIP services, support TR-069 remote management.

MDU (Multi.Dwelling Unit) multi-family unit ONU

Mainly used in FTTB / FTTC / FTTCab mode for multiple residential users occasions, with broadband access terminal functions, usually with at least 4 user-side interfaces in the telecom operators equipment selection, often including Ethernet interfaces, ADSL2 + Interface or VDSL2 interface to provide Ethernet / IP services. In the radio and television operators of the network applications, due to differences in business content, generally only contains the Ethernet interface for PON + LAN access.

MTU (Multi-tenant Unit) Multi-tenant unit type ONU

It is mainly used for multiple enterprise users in the FTTB scenario or multiple individual users in the same enterprise. It has the function of broadband access terminal and has multiple Ethernet interfaces (usually at least eight), E1 interfaces and POTS interfaces, and provides Ethernet Network / IP services, TDM services and VoIP services (built-in IAD).

SBU (Single Business Unit) single-business unit ONU

Mainly used in the case of FTTO, separate business users and businesses in a single office access. Support broadband access terminal functions, in the telecom operation network, generally with Ethernet interface, E1 interface, VOIP interface, etc., to provide Ethernet / IP services and TDM services.

If the OLT (the central node of the EPON) were to be implemented as a PHY with a single MAC attached to it, this would cause serious trouble for any bridge (=switch) to which the MAC were connected. Consider a MAC frame coming into the bridge from an ONU (a subscriber node) via an EPON port. The bridge associates the source address of the frame with the port on which it came in, i.e. the EPON port. When at a later time another MAC frame comes in from an ONU, this time destined for the MAC address previously learned, it will not be transmitted back to the EPON port, because the bridge assumes that the frame was already received by all the stations on the attached “broadcast” LAN. However, this is not the case; upstream transmissions are not received by other ONUs. Standard bridging has no way of accomodating an attached LAN that behaves as a broadcast LAN in downstream and as a point-to-point LAN in upstream.

The solution to this problem was designed in close cooperation with Working Group 802.1. Instead of one single MAC, the OLT would have a different dedicated MAC for every ONU attached to the EPON. As a result, higher layers can consider the EPON as a collection of logical point-to-point links. From the individual MACs down to the OLT PHY, the logical point-to-point links share a common GMII; hence, a way to identify data frames for/from the different ONUs is required. The Logical Link identifier (LLID) was created for this purpose. The LLID is carried along by the frame in the bytes of its preamble.