Telstra recently announced that it will upgrade its BigPond cable service in Melbourne to 100 Mbps by Christmas 2009. Big deal.

Somehow, this has excited some people. Alan Kohler, for example, writes, ‘Telstra’s decision to upgrade its cable definitely now means that the National Broadband Network won’t get built’.

Two problems immediately come to mind. First, you’ll never see those speeds. Even if you’re in an area that can get the upgraded cable service, the 100 Mbps is shared between a number of households. You can get the full 100 Mbps only if none of those households is using its cable broadband.

Second, if you’re ever lucky enough to see those speeds, you won’t see them for long. BigPond’s $139.95 cable plan includes only 60 GB of usage (uploads and downloads). At 100 Mbps, that lasts 80 minutes. Excess usage is charged at $1.88 per second.

Incidentally, Next G has the same problems, except that it’s slower and even more expensive. At its peak speed of 21 Mbps, the 10 GB you get for $129.95 lasts only 63 minutes. Excess is charged at $0.66 per second. Keep that in mind next time Telstra brags that its Next G network provides 21 Mbps to 99% of the Australian population.

Fast speeds seem to be more important to broadband users than large quotas. Perhaps that accounts for how little has been said about increasing download quotas in the context of the National Broadband Network debate.

But it should be obvious that increasing speeds without increasing quotas won’t enable the bandwidth-intensive applications that the government hopes to enable.