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Date: Fri, 19 Oct 2007 21:43:05 -0600 From: Sean Figgins <sean@labrats.us> To: nanog@nanog.org In-Reply-To: <!&!AAAAAAAAAAAuAAAAAAAAAKTyXRN5/+lGvU59a+P7CFMBAN6gY+ZG84BMpVQcAbDh1IQAAAATbSgAABAAAACaJvLu3TXUTrYkNySI8KsJAQAAAAA=@iname.com> Errors-To: owner-nanog@merit.edu Frank Bulk wrote: > 2) DSL and fiber have limitations, too. The modulation and spectrum width > can vary, but most MSOs have their forward configured with a maximum of > around 38 Mbps (256-QAM, 6 MHz wide) and the return in the 9 Mbps range > (64-QAM, 3.2 MHz wide). Charts here: > Forward: http://www.cable360.net/images/articles/15131_1168455349.gif > Return: http://www.cable360.net/images/articles/15131_1168455396.gif Thank you, Frank. I'm not a HFC engineer, but rather an IP/Network/Server/Security guy, that worked on the backbone and lab side of a large MSO. My HFC experience is exclusive of what is between the CMTS and the cable modem. I know just enough to be able to live there. I got my figures reversed. For some reason I was thinking that it was about 100 meg on the upstream and 45 meg on the downstream, but looks like I remembered it wrong. Anyways, regardless of that, you pretty much validated what I was saying as to the reason why a MSO would deploy such a device. It's possibly cheaper to do so than to deploy the hardware to split the HFC pland and increase available bandwidth to subscriber ratio. Not that I agree with such a practice. -Sean
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