"iiNet has end-to-end responsibility for their network, including managing the various network elements required to deliver reliable video streaming, one of which is traffic backhaul and interconnection," Mr Wright said in a statement to Fairfax Media on Wednesday. "It is the responsibility of each ISP to have sufficient backhaul capacity to deliver services to their customers." He added: "If customers of another ISP are experiencing congestion, insufficient backhaul could be one explanation or there may be other elements at play." iiNet customers worst hit include thousands in NSW, Victoria and Queensland using ADSL, and those using fibre offerings on the national broadband network and Opticomm's network. But a number of issues also exist in other states like WA and Tasmania.

While iiNet has not responded to repeated Fairfax Media requests for comment since Monday, its online fault status page lists dozens of notices concerning congestion on numerous ADSL exchanges and NBN "points of interconnect" - the NBN equivalent of ADSL exchanges - across Australia. Traffic growth underestimated But in a post on broadband forum Whirlpool on Tuesday night, Roger Yerramsetti, iiNet's network services manager, admitted the telco underestimated traffic level growth. They are hiding a lot and even publicly under-reporting the amount of Netflix traffic they are getting so people don't connect the dots and realise Netflix has crippled the network A person familiar with Netflix's impact on iiNet's network "In some areas we're seeing network traffic reach levels that were projected to occur well over 6 months from now, so under the bonnet we have been rapidly upgrading our network to keep pace with the demand and to ensure we're continuing to provide a high quality service," Mr Yerramsetti said.

Are you affected or do you know more? Email us It comes as a person familiar with Netflix's impact on iiNet, who didn't want to be named, said it was "crippling" iiNet's network. "[iiNet] are hiding a lot and even publicly under-reporting the amount of Netflix traffic they are getting so people don't connect the dots and realise Netflix has crippled the network," the person familiar with their network said. iINet last week said Netflix consumed about 15 per cent of its overall traffic. But the person familiar with their network said that while this was correct over a 24-hour period it was a much higher percentage for peak periods.

"That 15 per cent figure they reported earlier ... that's 15 per cent averaged over the course of a 24-hour period, when actual usage is heavily spiked between 6pm and 11pm AEST." The person said iiNet's engineering team knew about the problems, but needed to get approval to purchase extra backhaul capacity from third-party providers - which often locks telcos into multi-year contracts - to cope with the Netflix demand. Given TPG is soon set to acquire iiNet in a $1.4 billion deal, the person suggested now wasn't the best time to increase expenses but said no one they knew had been actively talking about this at the company as being the reason upgrades hadn't been done quicker. Some upgrades months away In most fault notices, many of which were made public after Netflix launched, iiNet says it is working to upgrade links over the next few days or weeks.

While some of iiNet's backhaul fibre links have been reaching capacity for some time during peak periods, Netflix is understood to have been the tipping point for large chunks of its network, pushing currently provisioned backhaul capacity in many areas to its limits. It appears iiNet either underestimated the amount of traffic Netflix would generate on its network or chose not to upgrade its infrastructure to cope until after the impact of the video streaming service was able to be measured. The problem has been exacerbated by the fact iiNet is offering Netflix quota-free, meaning many of its customers are hammering the service as Netflix doesn't count towards their download limit. The company has been making a big deal of the quota-free offer, even flying a plane above Melbourne's CBD with a banner trailing behind it to advertise it. The big question iiNet and other ISPs are wondering at the moment? Whether those signing up to the one-month free trial of Netflix will continue to use the service when the free trial expires. If they don't, some capacity upgrades done now may result in having too much supply and not enough demand.

Read more: These graphs show the impact Netflix is having on the Australian internet