CableLabs has quietly issued the eRouter specification, an optional spec that, in part, is viewed as a lightweight version of CableHome, a platform that enables operators to manage the home networks of customers.

Another key point: eRouter allows for both IPv4- and IPv6-enabled DOCSIS devices to connect to the Internet.

CableLabs officially issued the eRouter spec on Dec. 7, 2006, and has posted the technical details on its Web site (pdf).

Unlike CableHome, the slimmed down eRouter specs, among other items, do not include firewall capabilities. Another key difference is that the customer, rather than the operator, will have control of how the DOCSIS-based home networking device is configured.

"It's a cheaper version of CableHome," said CableLabs Vice President of Broadband Access Michelle Kuska, noting that the eRouter function can be incorporated in any DOCSIS 1.x modem.

Some in the industry believe that removing some of the complexity will translate into deeper deployments by operators.

Although much work was put into the CableHome 1.1 spec, "our observation is that it has not been widely deployed," said Wade Carter, director of engineering for the broadband division of ARRIS, which makes a line of cable modems, residential gateways and multimedia terminal adapters.

Vendors that opt to support eRouter will be able to do so via a software upgrade, according to Dan Torbet, a principal engineer with ARRIS.

eRouter will continue to accommodate IPv4 traffic and NAT, but will also lend support to IPv6, a key feature of the emerging DOCSIS 3.0 platform.

According to the specs, eRouter will operate in four modes:
- IPv4-only mode, passing through IPv4 traffic only
- IPv6-only mode
- Dual mode (passing both IPv4 and IPv6 traffic)
- Disabled mode - the eRouter transparently forwards all traffic directly between its customer- and operator-facing interface.

In terms of products that could support the new specs, Torbet pointed to several potential combinations, including a DOCSIS 2.0 modem with an attached IPv4 router, a DOCSIS 3.0 modem with single IPv4 or IPv6 support, or a dual IPv4/IPv6 configuration. Home networking gateways are also natural candidates.

While the release of the spec is a first formal step, much more work lies ahead, including defining the customer interface, Torbet explained.

For now, CableLabs has yet to finalize test plans for products that support eRouter. "We're discussing that with operators," Kuska said.