Telstra has been quick to respond to criticism of the capabilities of DOCSIS 3.0, and HFC networks in general, with a blog post on Nowwearetalking from its CTO, Hugh Bradlow.

Bradlow pointed out that "every telecommunications network since Alexander Graham Bell invented the telephone, has been, is and will be 'shared' – it really is just a question of where the sharing occurs and the network engineering required to make the network deliver the services to customers without them noticing the impact."

True, but it's a fact that cable people seem particularly reluctant to discuss. I'd asked Telstra's GMD Networks and Services, Michael Rocca the day of Telstra's announcement how many users in Telstra's Melbourne HFC network typically shared a single run of coax and if Telstra intended to reduce this number as part of the upgrade. I had great difficulty in getting him to answer the question, and he never did give me a number but did say that about 100 addition nodes would be rolled out as part of the DOCSIS 3.0 upgrade. According to Bradlow, the number of users per node in HFC networks is "typically 150" (but he did not suggest that this applied to Telstra's network).

Dermot Cox of C-COR Broadband - the main supplier of HFC gear to Telstra - made a submission to the Senate enquiry into the NBN. He had the hubris to claim that "The next wave of technology development will be driven by the world's leading cable operators to meet customers' increasing demand for more bandwidth and video-centric applications like IPTV, interactive video, distance education and video telephony. Not once did he mention that the capacity of DOCSIS 3.0 is shared between all users on a co-ax cable.

You can read Bradlow's full rap on the wonders of DOCSIS 3.0 on Nowwearetalking. According to Bradlow, it stacks up very favourably against FTTN. "When we say that Telstra's upgraded cable network will deliver up to 100Mbps downstream speeds, we mean it. Even in peak periods, the cable network will deliver 70 – 100Mbps burst downstream speeds, – a higher peak speed, in fact, than FTTN would offer."

Well if this is so, given all that Telstra has said about the need for and benefits of widespread high speed broadband one has to ask why it is dipping its toe into the water with DOCSIS 3.0 announcing only a Melbourne rollout when, on a simple extrapolation of the $300m cost, it could have 2.5m households in major cities able to access the network for about $700 and probably finish the job my mid 2010.

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