1. PPP over Ethernet protocol
The Ethernet online point-to-point protocol (PPP over Ethernet) technology, which was launched in late 1998, was jointly developed by Redback Network Company, client software developer RouterWare Company, and Worldcom subsidiary UUNET Technologies Company on the basis of the IETF RFC system. By combining the most economical LAN technology, the scalability and management control functions of Ethernet and point-to-point protocols, network service providers and telecom operators can use reliable and familiar technologies to accelerate the deployment of high-speed Internet services. It makes it easier for service providers to provide broadband access services that support multiple users through digital subscriber lines, cable modems or wireless connections. At the same time, this technology also simplifies the operation of end users when dynamically selecting these services.
2. PPP over Ethernet basic frame format
Establishing a peer-to-peer protocol session on Ethernet includes two stages: 1. Discovery stage. During the Discovery process, the user host broadcasts to find all access hubs that can be connected and obtains its Ethernet MAC address. Then select the host you want to connect to and determine the PPP session identification number to be established. 2. PPP conversation stage. The user host and the access hub perform PPP sessions based on the PPP session connection parameters negotiated in the discovery phase. Therefore, corresponding to these two processes, the point-to-point protocol frame format on Ethernet (as shown in Figure 2) also includes two types: the type field in the Ethernet frame in the discovery stage is 0x8863; the type field in the Ethernet frame in the PPP session stage is 0x8864, which have both been recognized by IEEE. The version (VER) field and type (TYPE) field in the PPPoE package are both 4 bits in length. In the current version of PPPoE recommendation, the values of both fields are fixed to 0x1. The code (CODE) field length is 8 bits and the values vary according to the different functions of various packets in the two phases. During the PPP session phase, the CODE field is 0x00, and the various packet formats in the discovery phase will be given in detail below when the discovery phase is introduced. The version identification number (SESSION_ID) field length is 16 bits, which is fixed during a given PPP session. The value 0xffffff is a reserved value. The Length (LENGTH) field is 16 bits long, indicating the PPPoE payload length. The discovery phase PPPoE payload can be empty or consist of multiple tags (TAGs), each tag is a structure of TLV (type-length-value); the PPP session phase PPPoE payload is a standard point-to-point protocol package.
3. Detailed introduction to the Discovery phase
A typical Discovery phase includes 4 steps: 1. The host issues a PPPoE effective discovery startup (PADI) package. The destination address of the Ethernet is the broadcast address 0xffffffffffffff, the CODE field is 0x09, and the SESSION_ID is 0x0000. The PADI package must contain at least one tag of service name type (the tag type field is 0x0101) to provide the requested service to the access hub. 2. After the access hub receives the PADI packet within the service scope, it sends a PPPoE valid discovery provision (PADO) packet to respond to the request. Its CODE field is 0x07 , and SESSION_ID is still 0x0000. The PADO package must contain a tag of the access hub name type (the tag type field is 0x0102) and one or more service name type tags indicating the type of service that can be provided to the host. 3. The host selects one of the multiple PADO packets that may be received, and then sends a PPPoE valid discovery request (PADR) packet to the selected access hub. Its CODE field is 0x19 , and SESSION_ID is still 0x0000. The PADR package must include a service name type tag to determine the type of service requested from the access hub. 4. After receiving the PADR packet, the access hub is ready to start a PPP session. It sends a PPPoE valid discovery session acknowledgement (PADS) packet. Its CODE field is 0x65 , and SESSION_ID is a unique PPPoE session identification number generated by the access hub. The PADS package must also contain a tag with access hub name type confirmation of the service provided to the host. When the host receives the PADS packet confirmation, both parties enter the PPP session stage.
There is also a PPPoE effective discovery termination (PADT) packet, which can be sent by either the host or the access hub at any time after a PPP session is established, indicating that the PPP session has been terminated. The PADT package does not require any tags, its CODE field is 0xa7 , and SESSION_ID is the session identification number of the PPP session that needs to be terminated.
4. Advantages of point-to-point protocol on Ethernet
The installation and operation methods are similar to the previous dial-up network mode, which is convenient for users to use.
The xDSL modem at the user does not require any configuration.
Allows multiple users to share a high-speed data access link. Adapt to small businesses and remote work requirements.
End users can access multiple ISPs simultaneously, and this dynamic service selection function can make it easy for ISPs to create and provide new services.
Compatible with all existing xDSL Modem and DSLAM.
It can be integrated with the existing access structure of the ISP.
Article entry: aaadxmm Editor in charge: aaadxmm
The Ethernet online point-to-point protocol (PPP over Ethernet) technology, which was launched in late 1998, was jointly developed by Redback Network Company, client software developer RouterWare Company, and Worldcom subsidiary UUNET Technologies Company on the basis of the IETF RFC system. By combining the most economical LAN technology, the scalability and management control functions of Ethernet and point-to-point protocols, network service providers and telecom operators can use reliable and familiar technologies to accelerate the deployment of high-speed Internet services. It makes it easier for service providers to provide broadband access services that support multiple users through digital subscriber lines, cable modems or wireless connections. At the same time, this technology also simplifies the operation of end users when dynamically selecting these services.
2. PPP over Ethernet basic frame format
Establishing a peer-to-peer protocol session on Ethernet includes two stages: 1. Discovery stage. During the Discovery process, the user host broadcasts to find all access hubs that can be connected and obtains its Ethernet MAC address. Then select the host you want to connect to and determine the PPP session identification number to be established. 2. PPP conversation stage. The user host and the access hub perform PPP sessions based on the PPP session connection parameters negotiated in the discovery phase. Therefore, corresponding to these two processes, the point-to-point protocol frame format on Ethernet (as shown in Figure 2) also includes two types: the type field in the Ethernet frame in the discovery stage is 0x8863; the type field in the Ethernet frame in the PPP session stage is 0x8864, which have both been recognized by IEEE. The version (VER) field and type (TYPE) field in the PPPoE package are both 4 bits in length. In the current version of PPPoE recommendation, the values of both fields are fixed to 0x1. The code (CODE) field length is 8 bits and the values vary according to the different functions of various packets in the two phases. During the PPP session phase, the CODE field is 0x00, and the various packet formats in the discovery phase will be given in detail below when the discovery phase is introduced. The version identification number (SESSION_ID) field length is 16 bits, which is fixed during a given PPP session. The value 0xffffff is a reserved value. The Length (LENGTH) field is 16 bits long, indicating the PPPoE payload length. The discovery phase PPPoE payload can be empty or consist of multiple tags (TAGs), each tag is a structure of TLV (type-length-value); the PPP session phase PPPoE payload is a standard point-to-point protocol package.
3. Detailed introduction to the Discovery phase
A typical Discovery phase includes 4 steps: 1. The host issues a PPPoE effective discovery startup (PADI) package. The destination address of the Ethernet is the broadcast address 0xffffffffffffff, the CODE field is 0x09, and the SESSION_ID is 0x0000. The PADI package must contain at least one tag of service name type (the tag type field is 0x0101) to provide the requested service to the access hub. 2. After the access hub receives the PADI packet within the service scope, it sends a PPPoE valid discovery provision (PADO) packet to respond to the request. Its CODE field is 0x07 , and SESSION_ID is still 0x0000. The PADO package must contain a tag of the access hub name type (the tag type field is 0x0102) and one or more service name type tags indicating the type of service that can be provided to the host. 3. The host selects one of the multiple PADO packets that may be received, and then sends a PPPoE valid discovery request (PADR) packet to the selected access hub. Its CODE field is 0x19 , and SESSION_ID is still 0x0000. The PADR package must include a service name type tag to determine the type of service requested from the access hub. 4. After receiving the PADR packet, the access hub is ready to start a PPP session. It sends a PPPoE valid discovery session acknowledgement (PADS) packet. Its CODE field is 0x65 , and SESSION_ID is a unique PPPoE session identification number generated by the access hub. The PADS package must also contain a tag with access hub name type confirmation of the service provided to the host. When the host receives the PADS packet confirmation, both parties enter the PPP session stage.
There is also a PPPoE effective discovery termination (PADT) packet, which can be sent by either the host or the access hub at any time after a PPP session is established, indicating that the PPP session has been terminated. The PADT package does not require any tags, its CODE field is 0xa7 , and SESSION_ID is the session identification number of the PPP session that needs to be terminated.
4. Advantages of point-to-point protocol on Ethernet
The installation and operation methods are similar to the previous dial-up network mode, which is convenient for users to use.
The xDSL modem at the user does not require any configuration.
Allows multiple users to share a high-speed data access link. Adapt to small businesses and remote work requirements.
End users can access multiple ISPs simultaneously, and this dynamic service selection function can make it easy for ISPs to create and provide new services.
Compatible with all existing xDSL Modem and DSLAM.
It can be integrated with the existing access structure of the ISP.
Article entry: aaadxmm Editor in charge: aaadxmm