Method for transmitting data of passive optical network data link layer

Abstract

The invention relates to a passive optical network data link road layer data transmission method, mainly including that when the data is transferred upwards, the whole transmission circulation is divided into a plurality of time slot, each optical network unit takes up one or more time slot to carry out data transmission, and each time slot consists of a pre-synchronization joint and at least one frame which uses label to carry out delimitation. The passive optical network data link road layer data transmission method of the invention has the advantages that the occupancy of the effective bandwidth is small, accurate frame delimitation can be carried out, the encapsulation mode is simple, the efficiency of the IP packet encapsulation is high, and the label retransmission is supported directly.

Description

technical field [0001] The invention relates to the communication field, in particular to a data transmission method of a passive optical network data link layer. Background technique [0002] Passive Optical Network (PON) is a technology that uses optical fiber to achieve broadband access for users. Existing access network technologies are mainly based on copper wires, such as cable modem (cable modem) and asymmetric digital subscriber line (ADSL), whose rate cannot be further improved, and there is a bandwidth bottleneck. With the growth of multimedia and real-time services, fiber-to-the-home will solve this bandwidth bottleneck, and the passive optical network is the most important implementation of fiber-to-the-home. [0003] At present, passive optical networks include asynchronous transfer mode passive optical network APON (ITU-T recommendation G.983), passive optical network EPON based on Gigabit Ethernet (IEEE standard 802.3ah) and gigabit passive optical network G...

AI Technical Summary

Problems solved by technology

Third, the preamble code originally used for frame delimitation identification is used for physical layer ID identification, which affects the frame delimitation identification effect, and a considerable part of the bytes are reserved to cause waste

Fourth, the existing frame delimitation identification method relies on the frame start byte delimitation, and its delimitation performance is not as good as the frame header verification synchronous search method, such as asynchronous transfer mode (ATM) encapsulation and general framing format (GFP) encapsulation

Fifth, according to the Ethernet encapsulation format, one IP packet can only be encapsulated into one Ethernet packet, and the encapsulation efficiency is low

[0011] The disadvantages of this scheme mainly include: first, since ATM belongs to fixed-length encapsulation (53 bytes), the encapsulation efficiency for variable-length IP packets is relatively low

Second, its header byte is used to store the virtual channel identifier VPI and the virtual circuit identifier VCI, which takes up limited space

Third, ATM encapsulation does not directly support label forwarding, and to implement label forwarding requires mapping between VPI / VCI and labels

Fourth, all physical layer overhead and control signaling overhead are carried with the frame within the frame, occupying effective bandwidth space

[0013] The main disadvantages of this solution include: First, the packaging method is quite complicated. Although the packaging efficiency is high, the implementation cost is too high

Second, the payload uses secondary encapsulation of the IP packet. The IP packet is first encapsulated in Ethernet (GEM) or ATM, and then encapsulated into the payload of the GEM, resulting in further waste of bandwidth.

Third, GEM encapsulation does not directly support label forwarding, and label forwarding needs to go through the mapping process between ATM encapsulation VPI / VCI and labels or add labels between Ethernet encapsulation and IP encapsulation

Fourth, its physical layer overhead and other control signaling overheads are still carried within frames, occupying effective bandwidth

[0014] The above three technologies now have international standards, and some products have come out, but they all have defects such as low data link layer network protocol (IP) packet encapsulation efficiency, no support for label forwarding, and poor service quality.

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