Network Architecture Options with PoE Media Converters
Multi-port PoE media converters enable a variety of flexible network designs. Typically, they feature single or dual RJ-45 ports to power one or two IP cameras per converter, and single or dual fiber ports.
PoE media converters with a single fiber port are deployed in a point-to-point, network star topology (see following image). In the following application example, IP cameras are installed throughout a facility. Fiber is distributed from a fiber switch (this can also be a copper switch and media converters). The fiber links connect to distant locations where PoE media converters are installed near AC or DC power sources. The PoE media converters convert the fiber to copper and inject PoE over the UTP cabling to the IP cameras.
PoE media converters with dual fiber ports support three types of network architectures: linear daisy chain, ring, and redundant.
The first architecture supports linking multiple PoE media converters in a linear daisy chain configuration (also known as a bus architecture) with a fiber uplink port and a fiber downlink port. This architecture can be used in a variety of applications where IP cameras are installed along railroad or subway lines, highways, perimeter fences, pipelines, etc. The advantage of daisy chaining is that it conserves fiber strands, but multiple devices can add potential points of failure, so daisy chains may not be the best design for mission-critical security applications. This is what a daisy chain design might look like:
The second architecture enables linking multiple PoE media converters in a ring (see image below). The fiber switch shown in this diagram supports Spanning Tree Protocol, which enables a resilient ring architecture. The advantage of a ring architecture is that in the event of a link failure, the fiber switch reroutes the traffic in the opposite direction on the ring.
The third architecture enabled by dual fiber ports is redundant fiber links for applications requiring fiber facility protection. There is an active fiber port, and a protection fiber port that can support a fiber failure switchover of less than 50 milliseconds.
In this application, redundant fiber is used for a mission-critical link to a PTZ IP camera that requires PoE+. The PoE+ media converter has one fiber port for the active fiber link, and one port for the protection fiber link, with fiber failure switchover of less than 50 milliseconds. The PoE+ media converter supplies power to the camera, and has power protection from an uninterruptible power supply (UPS) battery back-up. In the event of a fiber cut and a loss of power, the camera continues to send data on the protection link.
PoE media converters provide a flexible and cost-effective solution to power PoE-driven IP cameras, and overcome the distance limitations of copper UTP network cabling. They combine the benefits of PoE and fiber in a compact and reliable device that supports PoE+ for the higher power requirements of today’s sophisticated security and surveillance cameras.
About the author: Ty Estes is the marketing communications director for Omnitron Systems. Omnitron is based in Irvine, California, and is a leading manufacturer of fiber connectivity solutions, including PoE and PoE+ media converters.