Formerly known as Narad Networks, the PhyFlex Networks product line (which was formerly known as the Narad Broadband Access Network, or NBAN) is a hardware platform targeted primarily to cable providers that enables them to provide switched Ethernet data services over their existing coax infrastructure. Such services are symmetrical and support data speeds of up to 100 Mb/sec. While supporting burst speeds of up to 100 Mb/sec, the vendor notes typical provisions to the end users of 5x5 Mb/sec, 10x10 Mb/sec, etc.

Originally targeted to the delivery of switched Ethernet over coax, the latest entry in the product family--the FTTxSWITCH--facilitates the injection of switched Ethernet transmissions over fiber or copper infrastructures, as well. While the coax-based transmissions are limited to symmetrical 100 Mb/sec speeds, the delivery of switched Ethernet over fiber or copper infrastructures can be run at speeds of up to 1 x 1 Gb/sec per user over fiber or copper.

A key feature of the vendor's Ethernet over coax platform is its "light touch" architecture, which means that only the passive filters (Coax Diplexer Filters) of the coax infrastructure must be directly touched by the Ethernet data delivery and therefore existing coax networking gear such as active amplifiers from the node to the customer remain unchanged. PhyFlex achieves this performance by leveraging an unused spectrum of bandwidth above 860 MHz but below 1.2 GHz. In brief, the PhyFlex platform injects a switched Ethernet services overlay into this frequency spectrum. The Ethernet signals are filtered (via the Coax Diplexer Filters described above) to special Coax Access Switches, while remaining coax services remain untouched and pass through existing amplifiers on their way to the end users. The point-to-point switched nature of the Ethernet services allows for the signals to be successfully passed within the 860 MHz-1.2 GHz spectrum; the signals are digitally regenerated at each switch, shortening the HFC span and therefore tolerating more end to end plant noise.

The four key components of the PhyFlex architecture are:

- The FTTxSWITCH, an environmentally hardened outdoor switch that can deliver carrier Ethernet services over fiber, copper coax, or wireless APs. The switch includes six fiber/Ethernet ports and four coax ports, and the vendor notes it can be deployed in FTTN, FTTC and FTTP configurations. Features include support for line rate traffic classification and filtering.

- The Coax Diplexer Filter (CDF), which provides the ability to filter the Ethernet services both into and from the coax infrastructure.

- The Coax Access Switch (CAS), which is colocated with the active amplifiers as they occur between the node and the customer. As described above, the CAS receives and regenerates the Ethernet services, obtaining and then injecting the services around the active amplifier via the CDFs. The CAS is also deployed prior to the customer reception of the Ethernet services; i.e., the CAS acts as a tap to deliver the switched services to the CDU.

- Finally, the Coax Demarcation Unit (CDU) is the customer premise equipment, including both customer coax and Ethernet ports.

The PhyFlex product line is available now. Contact the vendor for further information.