Cisco has dropped an open reference design for DOCSIS silicon into the CableLabs standards body.

The group has been working on Full Duplex DOCSIS for some time, and in February announced that the gigabit up / gigabit down effort was worth pursuing.

Switchzilla has been pursuing it, and has handed over its design for a digital echo canceller that integrates with DOCSIS Cable Modem Termination System (CMTS) standards (CMTS specifications cover the cable hubs on the provider side of the network).

Cisco says the echo canceller will work for upstream carrier frequencies from 200 MHz (1.7 Gbps) all the way to 1.2 GHz (for a 10 Gbps upstream channel).

While Cisco hasn't detailed the specifics of the echo cancellation reference design, by providing it royalty-free through CableLabs the company hopes to give the Full Duplex effort a kick along.

The current DOCSIS 3.1 spec supports 10 Gbps down but a maximum of only 1 Gbps upstream.

The CableLabs feasibility study in February was followed by a Nokia demonstration in May. Nokia's Bell Labs showed that a point-to-point hybrid fibre-coax network can hit 10 Gbps symmetrical speeds.

Nokia's announcement of XG-CABLE notes that the 10 Gbps symmetrical demonstration works at distances of 200 metres.

While Full Duplex pushes symmetrical 10 Gbps services closer to reality, switching HFC from a shared topology to point-to-point is a big change to the physical architecture, demanding operators drive fibre deeper into their networks.

Faced with a need to replace head-end hubs, consumer modems, and physical topology, cable operators might decide to pull the fibre all the way to the customer. ®