Extended ECC

Definition of Extended ECC

The physical layer of the ECC is the DCC/GCC, which is transmitted based on the fiber. In certain cases, the network or NE may be independent and there is no DCC/GCC channel to the gateway NE (no fiber connection).

The extended ECC refers to the HWECC 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/GCC channel and that of the extended ECC is an extended channel (such as an Ethernet channel).

Networking

There are three networking modes for the extended ECC:

• Using the network cable

  Use a network cable to directly connect the Ethernet NM ports (NM_ETH) of the two NEs.

• Using the hub

  Use a hub or other data communication equipment to connect the Ethernet NM ports (NM_ETH) on the system control unit of related NEs.

• Using network cables to connect NEs in series

  The Ethernet NM ports (NM_ETH) on the board of the equipment are equivalent to lots of ports on a hub. Hence, you can use network cables to connect NEs in series. Such series connection is equivalent to the hub connection.

NOTICE:

• If you use a hub to connect NEs or use network cables to connect NEs in series, there must be no network loop in the Ethernet. Otherwise, a broadcast storm occurs and the system control unit is repeatedly reset.
• Either a straight-through cable or a crossover cable can be used as the network cable for the extended ECC.

Extended ECC Modes

Extended ECC communication uses TCP connections to establish MAC connections between adjacent NEs. Extended ECC communication can be implemented in two modes.

• Auto Mode

  On an Ethernet, the NE with the largest IP address automatically functions as the server and other NEs as clients. The server and clients automatically establish TCP connections between them and subsequently automatically establish MAC connections based on the TCP connections. In auto mode, users do not manually specify the server and clients. The implementation principle is as follows:

  1. Each NE obtains the IP addresses of other NEs that are on the same Ethernet through the address resolution protocol (ARP).
  2. The NE with the largest IP address automatically functions as the server and detects the TCP requests from the clients.
  3. Other NEs automatically function as clients and send TCP connection requests to the server.
  4. After receiving the TCP connection request from a client, the server establishes the corresponding TCP connection.
  5. The NEs use the TCP connection as a MAC connection to achieve ECC communication.

  In auto mode, the extended ECC supports a maximum of eight NEs (the sum of the server and clients).

• Specified Mode

  NEs establish TCP connections between the server and clients based on the specified server, clients, and port numbers and establish MAC connections based on the TCP connections. In specified mode, one server can connect to a maximum of seven clients. When the number of clients exceeds the maximum value, users can configure multi-level extended ECC to increase the number of allowable clients. For example, configure an NE as server 1 and connect it to seven clients: client 11 to client 17. Then configure client 17 as server 2 and connect server 2 to another seven clients: client 21 to client 27. When using multi-level extended ECC, the connecting ports in each extended ECC group must be different.

NOTE:

By default the auto mode is enabled for extended ECC.