Technical description of broadband Ethernet access

Ethernet is a local area network technology developed in the the 1980s, because of its easy to use, low price and high speed, it soon became the mainstream of LAN. With the advent of Gigabit Ethernet (GbE) and the emergence of Gigabit Ethernet (10GbE), as well as the low cost of direct architecture of GbE and 10GbE technology in optical fiber, Ethernet has entered the metropolitan area and wide area network. If the access network also uses Ethernet will form from LAN, access network, metropolitan area network to WAN is all Ethernet structure. Using a unified Ethernet frame structure consistent with IP, seamless connection between the Nets, without any format conversion in the middle, will improve operational efficiency, facilitate management and reduce costs.

But because the access network is a common network environment, therefore, its requirements and LAN such a private network environment will be very different, it only borrowed for the local area Ethernet frame structure and interface, network structure and working principle is completely dissimilar, the difference is mainly reflected in user management, security management, business management and billing management.

User management refers to the user needs to access network operators there to open an account registration, and in the user communication to the user authentication, authorization, to ensure that legitimate users of normal communication, to eliminate the invasion of illegal users. Security management refers to the access network needs to protect the user data (unicast address frame) of the security, isolation carry a user's personal information broadcast messages (such as Address Resolution Protocol (ARP), Dynamic Host Configuration Protocol (DHCP) messages, etc.), to prevent critical devices from being attacked. Business management means that the access network needs to support multicast service, which needs to provide some means for guaranteeing QoS. Billing management refers to the access network needs to provide information about the billing, billing problems for any one way of accessing is necessary.

The broadband access network based on Ethernet technology consists of a local terminal device and a client device, the local terminal equipment is generally located in the district or the commercial building, the client equipment is generally located in the residential building; The local device provides the interface with the IP backbone, and the client device provides the 10,100base-t interface with the user terminal computer. The client device is different from the Ethernet switch, the Ethernet switch isolates the unicast data frame, and the data frame of the broadcast address is not isolated, but the function of the client device is only the multiplexing and multiplexing of the Ethernet frame; The local terminal device is different from the router, the router maintains the port-network address map, The Port-Host address mapping table is maintained by the local-side device. The client device has only link layer functionality, work in the multiplexer mode, each user in the physical layer and link layer isolation, so as to ensure the security of user data; The local terminal equipment supports the user's authentication, authorization and billing as well as the dynamic distribution of the user's IP address, and also has the function of pooling the network information of the client device.