The background and introduction of PPPoE protocol

Details of the two phases of PPPoE protocol: Discovery phase Session, to introduce the PPPoE protocol method, may be a lot of people do not understand how to optimize the PPPoE protocol, no relationship, after reading this article you certainly have a lot of harvest, I hope this article can teach you more things.

The background of the PPPoE protocol

with the continuous development of broadband network technology, several mainstream broadband access technologies, mainly xDSL, Cablemodem and Ethernet, have been launched in full swing. At the same time to the major network operators have brought a variety of puzzles, no matter what access technology to use, for them to be expected and can be asked how to effectively manage users, how to collect returns from the investment in the network, so the various broadband access technology fees become more sensitive to the issue.

in the traditional Ethernet model, we do not have the concept of the so-called user billing, or users can set up/Get IP address to the Internet, or users can not access the Internet. IETF engineers have developed a protocol for the transmission of PPP packets on the Ethernet network (point to point Protocol over Ethernet) in line with the operation of narrowband dial-up Internet (using NAS devices to terminate a user's PPP packet).

After the introduction of this protocol, network equipment manufacturers have also launched their own brand of broadband access server (BAS), which can not only support the end of the PPPoE protocol data packets, but also support many other protocols. such as the  Company's MA5200 (small bas) and ISN8850 (great bas).

The introduction to the PPPoE protocol

The PPPoE protocol provides a standard for multiple hosts connected to a remote access concentrator in a broadcast network (such as Ethernet) (we have a broadband access server for the device that is currently capable of completing the above function). In this network model, it is easy to see that all users ' hosts need to be able to initialize their own PPP protocol stack independently.

and through some of the characteristics of the PPP protocol itself, it is possible to charge and manage users on a broadcast network. In order to establish and maintain the point-to-point relationship between hosts and access concentrator on a broadcast network, it is necessary to establish a unique point-to-point session between each host and the access concentrator. The

PPPoE protocol consists of two phases, the discovery phase of PPPoE (PPPoE Discovery Stage) and the session phase of PPPoE (PPPoE sessions Stage). In this training material is more focused on the introduction of the PPPoE discovery phase, because for the session phase of PPPoE, can be seen as the PPP session process is the same (can be directly referred to the PPP Protocol training materials), and the mainThe difference is that the packet headers of PPPoE are encapsulated only in front of the PPP data message.

Any phase of the data message is eventually routed through a frame encapsulated in Ethernet. When a host wants to be able to start a PPPoE session, it will first be said in the Broadcast Network (protocol), but in practical applications, it may be necessary to cross over a number of network access, such as ATM, so as to form a PPPOEOA packet on the search for an access concentrator.

Of course, there may be multiple access concentrator on the network, and for the host, the choice will be based on the services provided by each access concentrator (ac,access concentration) or the user's prior configuration. When the host chooses the required access concentrator, it starts and accesses the concentrator to establish a PPPoE session process. The

Access Concentrator In this procedure assigns a unique process ID to each PPPoE session, and the session is established to begin the session phase of PPPoE, in which the two sides of a point-to-point connection have been established (the point to point structure is not the same as PPP, It is a kind of logic point to point relation) to use PPP protocol to Exchange data packets, so as to complete a series of PPP process, will eventually be in this point-to-point logical channel on the network layer datagram transmission.

PPPoE Protocol summary

The PPPoE protocol includes the discovery phase of PPPoE and the session phase of PPPoE. Most BAS (broadband access servers) support the PPPoE protocol.

PPPoE protocol think

PPPoE client is based on what criteria to access the concentrator?