NBN Co is imposing new limits on satellite downloads, forcing ISPs to kill off plans with more than 50 GB monthly allowances.

According to documents seen by The Register, the network-builder is once again finding its Interim Satellite Service effectively DDoSed by its popularity.

“In response to complaints about poor performance of the NBN Interim Satellite Service at peak hours, NBN Co has recently taken steps to improve performance by adding additional bandwidth. However, NBN Co now wants all Retail Service Providers (RSPs) to withdraw Plans that have large anytime data allowances,” says an ISP's notice to a customer.

The user who contacted Vulture South says his country-town computer business will be severely constrained when his ISP, SkyMesh, withdraws the current 100 GB-allowance plan and migrates him to a 20 GB plan.

In February 2014, as captured by the Wayback machine, SkyMesh offered plans “with data allowances from 3 GB all the way up to 500 GB per month”. The company's published plans now max out at 20 GB per month.

(It should be noted that nearly all of the most generous plans of the 2014 price book were for "night owls", and only included 2 GB of peak data.)

The ISP's customer told The Register “The introduction of these new restrictions penalises agricultural businesses and businesses servicing the rural sector such as my own and will have an adverse impact on schools, medical services or any institution dependent on NBN satellite broadband services for their Internet”.

He added that while NBN Co announced its intention to manage satellite usage in March 2013, the 50 GB limit (even for users paying for more) was only communicated to him recently.

In a “messaging for ISPs” document apparently from NBN Co, the company tells retail ISPs to emphasise that “NBN Co expects that less than 5% of ISS users will likely be impacted by the application of a download limit”.

The payoff, NBN Co says, would be that “NBN Co expects that on average, end users will receive access to around a third more capacity during peak periods, which will enable them to better carry out tasks like email, Internet banking and Voice over Internet Protocol (VOIP) services, such as Skype”.

The new satellite restrictions come into effect as NBN Co trumpets the completion of construction on the ten ground stations needed to connect NBN Co's own satellites. The first launch is expected in 2016 (but has been delayed by five months).

The Register has asked NBN Co to comment on the withdrawal of high-usage plans. ®

Update: NBN Co has responded, telling Vulture South “It’s about a fair go for everybody.”

While the long-term satellite service will support 400,000 users, “The interim satellite service … is designed to serve a maximum of 48,000 users only. That’s based on the fact that we’re only able to lease a finite amount of bandwidth from commercial operators.”

The company continued: “some very heavy users of satellite broadband were crowding out the majority. So we began for the first time enforcing the fair use measures that had always been in place (but up until then had never been used).”

NBN Co also provided some “dot points” which pretty much check off against the messaging RSPs are expected to use when explaining the new enforcement of the fair use policy.

The Register notes that while media are told the limit is 50 GB per month, it's actually calculated on a rolling four-week average. In other words, a user consuming 25 GB in the last week of their billing period, and another 25 GB in the first week of the next, would find themselves in breach of the policy. ®