SFP, SFP+ Optical Transceivers modules

What is DDM

Ethernet is a technology that is defined by IEEE 802.3 standard. This standard defines the types of media, wire, fiber optics and wireless, the electrical characteristics and the addressing scheme for an Ethernet network.

Ethernet is a packet communications technology, designed for computer to computer communications. The rules concerning Ethernet communications assumes every machine is connected to the same piece of wire, much like a meeting of a group of people in one room. If a machine wants to communicate (talk) it listens and if there is nothing on the wire it talks. If two machines talk at the same time they hear each other so they back off and wait a random time period then try again.

Today's Ethernet networks use switches to create a network and every device is communicating on a full duplex connection, over Twisted pair wire, fiber optic cable or wireless channels, so there are never two machines sending at the same time, on the same piece of wire. This changes the dynamic of how the network operates and allows Ethernet networks to go where they could not go before the development of switches.

Distributed networks, such as Traffic Signal Networks or Highway Management Networks present a special challenge because the location of Ethernet switches is sometimes miles apart from each other and miles from the central control center. When a network uses fiber optic cable the connectivity generally follows the concept shown below.

Using the recently released DDM/DOM from EtherWAN a user can use the industrial Ethernet switch management functions to trouble shoot fiber optic connectivity issues.

The DDM/DOM subsystem is available through the switch management screens. Whether using a web browser, telnet or the console port, a user can access this information for any switch in the network from any location on the network. In the system, DDM/DOM measures and monitors the operating parameters of the SFP module, including the optical characteristics and displays a set of parameters that allow users to determine the health of the laser as well as the performance of the fiber optic cable plant. Parameters include optical output power (TX Power), optical input power (RX Power), temperature, laser bias current (TX bias current), and transceiver supply voltage (VCC). The DDM interface allows users to retrieve diagnostic data and alarms for SFP that are used to diagnose why a SFP is not working.

Industrial Ethernet switches with DDM/DOM allow users of distributed networks that utilize fiber optic cable to be more proactive in maintaining their network using the than standard optical interfaces. The results are fewer truck rolls, less network down time, less investment in equipment and training and smoother operation.