The DCN provides communication channels for the NEs that are managed in a centralized manner to manage and maintain the NEs remotely. From a broad sense, a network for data communication can be called a DCN.
Huawei DCN Solution
For various networking modes of the transmission equipment, the OptiX transmission equipment of Huawei provides multiple DCN solutions.
HWECC Solution
When the networking is comprised of only the OptiX transmission equipment, the HWECC solution is preferred.
In this solution, NEs transmit the data that supports the HWECC protocol through DCCs. The solution features easy configuration and convenient application. As the HWECC protocol is a proprietary protocol, the management problems cannot be solved when the networking is comprised of both the OptiX equipment and the third-party equipment.
IP over DCC Solution
When the networking is comprised of both the OptiX transmission equipment and the third-party equipment that supports the IP over DCC function, the IP over DCC solution is preferred. The IP over DCC solution can also be applied when the networking is comprised of only the OptiX transmission equipment.
In the IP over DCC solution, NEs transmit the data that supports the TCP/IP protocol through DCCs. As the TCP/IP protocol is a standard protocol, the management problems are solved when the networking is comprised of both the OptiX equipment and the third-party equipment. The configuration of the IP over DCC solution is more complicated than that of the HWECC solution.
OSI over DCC Solution
When the networking is comprised of both the OptiX transmission equipment and the third-party equipment that supports the OSI over DCC function, the OSI over DCC solution is preferred.
In the OSI over DCC solution, NEs transmit the data that supports the OSI protocol through DCCs. As the OSI protocol is a standard protocol, the management problems are solved when the networking is comprised of both the OptiX equipment and the third-party equipment. The configuration of the OSI over DCC solution, however, is more complicated than the configurations of the HWECC solution and the IP over DCC solution.
DCC Transparent Transmission Solution
When the networking is comprised of the OptiX transmission equipment and the third-party equipment that does not support the IP over DCC function or the OSI over DCC function, this solution is adopted.
In the solution, vendors use different DCCs to transmit data. Therefore, the management problems are solved when the networking is comprised of both the OptiX equipment and the third-party equipment. As the NMS of a vendor can manage only the NEs of the vendor, there is a great limitation.
HWECC Solution
HWECC Protocol
ITU-T G.784 defines the architecture of the ECC protocol stack based on the OSI seven-layer reference model. The HWECC protocol stack is based on the ECC protocol stack.
The HWECC protocol consists of four layers: physical layer (DCC), media access layer, network layer, and transmission layer. See Figure 1.
Figure 1 Architecture of the HWECC protocol stack
Physical layer
The main function of the physical layer is to control physical channels. The physical layer performs the following functions:
◆Receives and sends data over the physical channels, including receiving data from physical channels and transferring the data to the upper layer.
◆Receives the data frames transferred from the upper layer and sends them to physical channels.
The channels at the physical layer include DCC channels and extended ECC channels. The physical layer can process the data frame with a maximum of 1024 bytes.
Media access layer
The media access layer is also called the medium access control (MAC) layer. The main function of the MAC layer is to activate or close physical DCCs between the physical layer and the network layer. The MAC layer shields the diversity of the physical networks and provides the uniform service upwards (point-to-point physical channel). The MAC layer performs the following functions:
◆Establishes and maintains the MAC connection between adjacent NEs.
When there is a reachable physical channel between two adjacent NEs, the MAC layer establishes a MAC connection between the NEs. Each MAC connection includes the address of the opposite NE, the ID of the physical channel, the connection timer, and other information.
◆Provides the data communication service.
The MAC layer receives the data frame transferred from the physical layer. If the destination address is the local station, the MAC layer transfers the data frame to the network layer. Otherwise, the MAC layer discards the data frame.
The MAC layer sends the data frame from the network layer. If the destination address of the data frame has a MAC connection, the MAC layer sends the data frame to the corresponding physical channel in the physical layer through the MAC connection. Otherwise, the MAC layer discards the data frame.
Network layer
The main function of the network layer is to provide the route addressing for data frames and the route management for the DCC communication network. The network layer performs the following functions:
◆Establishes and maintains ECC routes.
Each route item includes the following information: address of the destination NE, address of the transfer NE, transfer distance (the number of passed transfer NEs), route priority (The priority value ranges from 1 to 7. The priority of an automatically established route is 4 by default. The system always selects the route with the highest priority.), and mode (0 represents the automatic route and 1 represents the manual route).
◆Provides the data communication service.
The network layer receives the packet transferred from the MAC layer. If the destination address of the packet is the local station, the network layer transfers the packet to the transport layer. Otherwise, the network layer requests the MAC layer to transfer the packet to the transfer station according to the route item that matches the destination address in the network layer routing table.
The network layer sends the packet from the transport layer. The network layer requests the MAC layer to transfer the packet to the transfer station according to the route item that matches the destination address of the packet in the network layer routing table.
Transport layer
The main function of the transport layer (L4 layer) is to provide the end-to-end communication service for the upper layer. As the communication between the OptiX equipment and the U2000 is controlled by the end-to-end connection-oriented service in the application layer, the L4 layer provides only the end-to-end connectionless communication service, that is, transparent data transfer service.
Extended HWECC
The physical layer of the ECC is DCC, whose data is transmitted based on the fiber. In certain cases, the network or NE may be independent and there is no DCC channel to the gateway NE (no fiber connection). The extended ECC refers to the ECC protocol stack that is loaded on the TCP/IP protocol stack. That is, the HWECC protocol stack is carried through the extended channel (such as Ethernet) instead of the DCC channel to meet the requirements of special scenarios. The difference between the extended ECC and the ECC is that the physical layer of the ECC is the DCC channel and that of the extended ECC is an extended channel (such as Ethernet channel). Figure 2 shows the networking environment with the extended ECC.
Figure 2 Networking environment with the extended ECC
Networking
The HWECC protocol supports various networking modes. NEs can be connected through optical interfaces or Ethernet ports for ECC communication. In certain situations, the HWECC protocol supports transparent transmission of the OAM information from the third-party equipment.
The HWECC protocol has the following typical applications depending on the networking.
Networking That Involves Only Huawei Equipment
Figure 1 shows the networking that involves only Huawei equipment.
Figure 1 Networking that involves only Huawei equipment
图3
When the network management information is transmitted between Huawei optical network equipment, there must be a gateway NE that communicates with the U2000. The U2000 is connected to the gateway NE through Ethernet. Hence, you can test, manage and maintain the entire network. The U2000 improves the quality of services (QoS) on the network and lowers the expenditure for maintenance. This ensures the rational use of network resources. Non-gateway NEs are connected to the gateway NE through the ECC. This realizes the information transmission between the U2000 and the non-gateway NEs. In addition, the extended ECC communication between NEs can be performed through network interfaces, such as NE6 and NE7.
Networking That Involves Huawei Equipment and Third-Party Equipment
Figure 2 shows the networking that involves Huawei equipment and third-party equipment.
Figure 2 Networking that involves Huawei equipment and third-party equipment
图4
For such networking, the OAM information of the third-party equipment should travel through Huawei equipment, which provides the function to transparently transmit the DCC. During the transmission, Huawei equipment does not analyze the data. To realize the DCC transparent transmission, perform the corresponding configuration at each NE along the data transmitting trail.
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