EPON ONU and GPON ONU main difference
EPON and GPON as the two main members of the optical network access, they have their own advantages, mutual competition, complement each other, learn from each other, in the following comparison of them in all aspects:
EPON provides fixed uplink and downlink 1.25Gbps, using 8b / 10b line coding, the actual rate of 1Gbps.
GPON supports a variety of rate levels, which can support asymmetric uplink and downlink rates, downlink 2.5Gbps or 1.25Gbps, uplink 1.25Gbps or 622Mbps. According to the actual demand, GPON determines uplink and downlink rates, selects the corresponding optical module, and increases the rate-to-cost ratio of optical devices.
This conclusion: GPON is better than EPON.
Operate and maintain OAM
EPON does not overemphasize OAM, simply defines the ONT far-end fault indication, loopback and link monitoring, and is optional support.
GPON defines PLOAM (PhysicalLayerOAM) at the physical layer, OMCI (ONTManagementandControlInterface) at the upper layer, and OAM management at multiple levels. PLOAM for data encryption, status detection, error monitoring and other functions. The OMCI channel protocol is used to manage the services defined by the upper layer, including the ONU function parameter set, the type and quantity of T-CONT services, QoS parameters, request configuration information and performance statistics. The OMCI channel automatically notifies the system of running events, Troubleshooting, performance and safety management.
This conclusion: GPON is better than EPON
Link layer encapsulation and multi-service support
As shown in Figure 2, EPON follows a simple Ethernet data format, but adds a 64-byte MPCP point-to-multipoint control protocol in the Ethernet header to realize bandwidth allocation, bandwidth round robin, automatic discovery in the EPON system, Ranging and other work. Much research has not been done on the support of services other than data services such as TDM synchronization services. Many EPON manufacturers have developed some non-standard products to solve this problem, but they are not ideal and it is difficult to meet carrier-class QoS requirements.
GPON is based on a completely new Transport Convergence (TC) layer that can accommodate high-level diversity services as shown in Figure 2. ATM encapsulation and GFP encapsulation (Universal Framing Protocol) are defined, and both can be chosen One of the business package. In view of the fact that ATM applications are not popular at the moment, a GPON supporting only GFP encapsulation is therefore available. lite device came into being, it ATM from the protocol stack to reduce costs.
GFP is a universal link layer protocol for a variety of services, defined by ITU. 7041. A few changes were made to GFP in GPON. A PortID was introduced at the head of the GFP frame to support multi-port multiplexing. A Fragment fragmentation indicator was also introduced to increase the effective bandwidth of the system. And only supports data processing mode for variable-length data without data-oriented block-oriented data processing mode, GPON has a strong multi-service carrying capability. The TC layer of GPON is essentially synchronous and uses a standard 8kHz (125μm) fixed-length frame, which enables GPONs to support end-to-end timing and other quasi-synchronous services, especially directly supporting TDM services, the so-called NativeTDM, GPON has "natural" support for TDM services.
This conclusion: The multi-service support of GPON's TC layer than EPON MPCP powerful.
Network level GPONEPON
L2ETHERNETETHERNET WITH MPCP
GPON and GPON have their own strengths and weaknesses. GPON is superior to EPON from the performance index. However, EPON has the advantages of time and cost. GPON is catching up and looking forward to the future broadband access market. GPON will be more suitable for customers with high bandwidth, multi-service, QoS and security requirements and ATM technology as the backbone. For cost-sensitive, QoS, security, less demanding customer base, EPON has become the dominant