[e2e] Spec for cable-based home networking

Mandin, Jeff Jeff.Mandin at ti.com
Wed May 8 02:42:22 PDT 2002

The e2e (or midcom) communities might be interested in a
home networking standard called CableHome being promoted by
the Cable industry group CableLabs.

Currently CableHome is a specification for a Service Provider
-managed  Residential Gateway unit (including a Firewall/
DHCP Server and coupled with a Cable Modem).  

Features that might be of interest include:

1. Support for multiple "public" IP addresses behind a single 
cable modem on a home network.

2. Explicit embrace of NAT.  The spec gives the Service 
Provider the ability to monitor or limit the number of hosts 
on the home network using NAT.

3. The Residential Gateway unit does not include a DHCP relay 
agent, so if multiple public IP addresses are present on the 
home network, they might reside on different Logical IP 
Subnets (LISes).  CableHome requires the Residential Gateway 
to maintain knowledge of individual IP addresses and intercept 
and route packets destined to an in-home IP address regardless 
of the packet's destination MAC.(Similar to the "Layer 3 bridge" 
function of Windows XP or the Bay Networks SwitchNode).

4. No support for DSL-style ISP selection.

The MIB syntax allows for IPv6 definitions, but the spec doesn't
really deal with IPv6 currently.

The specification and MIBs are located at


Jeff Mandin
Senior System Architect(Software)
Texas Instruments - Cable Broadband Communications
email: jeff.mandin at ti.com

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