The element management system (EMS) sets up communication with NEs through a data communication network (DCN), to manage and maintain these NEs.
In a DCN, the EMS and NEs are both regarded as network nodes, which can be connected through Ethernet or physical data communication channels (DCCs).
In practical networking, the EMS and NEs can be located on different floors in a building, in different buildings, or even in different cities. Therefore, the connection between the EMS and NEs usually requires an external DCN that is composed of equipment such as LAN switch and routers. On the other hand, the DCN among NEs is referred to as an internal DCN. This topic describes the internal DCN composed of NEs. See Figure 1.
External DCN
In general, an external DCN is a local area network (LAN) or a wide area network (WAN) and uses the Transmission Control Protocol/Internet Protocol (TCP/IP) or the Open System Interconnection (OSI) protocol for communication. It mainly provides communication between NMSs and communication between the NMS server and GNEs. The details are as follows:
- Communication between NMSs
The communication between NMSs includes the following parts: communication between the NMS server and the operations support system (OSS), communication between the NMS server and clients, and communication between the primary and secondary sites in a high availability (HA) system. The NMS communication can be implemented only using the TCP/IP protocol.
- Communication between the NMS server and GNEs
The NMS server and GNEs may be located on different floors of a building, in different buildings, or even in different cities. Hence, an external DCN that is comprised of the data communication devices, such as LAN switches and routers, is required to connect the NMS server and the GNEs. This type of communication can be implemented using either the TCP/IP or OSI protocol.
Usually the NMS server connects to GNEs in the following two modes:- The NMS server connects to GNEs through Ethernet switches.
This mode applies when the distance between the NMS server and each GNE is smaller than or equal to 100 m and no other Ethernet networks are available between the NMS server and the GNE.
- The NMS server connects to GNEs through routers.
This mode applies when the distance between the NMS server and each GNE is greater than 100 m and an Ethernet network is available between the NMS server and the GNE.
NOTE: The DCN communication between the NMS server and GNEs belongs to the data communication domain and therefore is not elaborated in this document. The DCN mentioned in this document refers to the internal DCN, unless otherwise specified.
- The NMS server connects to GNEs through Ethernet switches.
Internal DCN
An internal DCN provides communication between NEs using the HWECC, TCP/IP, or OSI protocol. The protocol packets are transmitted over optical supervisory channels (OSCs) or electric supervisory channels (ESCs).