NBN Co plans to schedule a weekly "change window" between 2am and 6am where it can service its B2B gateway - the IT interconnection point with ISP systems.
The network builder shed light on the architecture and operation of the gateway in a series of changes made to its technical specifications published over the weekend.
The physical gateway itself will be an IBM WebSphere DataPower XB60 appliance, touted by Big Blue as a way to "extend your business to... customers and partners with DMZ-grade security".
All interactions between NBN Co and access seekers – such as address searches, orders and service desk tickets – would pass between the B2B gateway and the ISP's message service handler (MSH).
NBN Co said it was "conscious" of the impact that any scheduled or unscheduled outages to the B2B gateway would have on ISPs servicing their customers.
"We aim to achieve scheduled service hours of 24x7 except for a weekly change window (requiring prior notification of outage) between 2am and 6am (exact outage window to be confirmed)," the network builder said.
"NBN Co commits to provide better than 95 percent availability of interactions to support processes to fulfil, assure and bill services when measured over any 60-day period, excluding planned outages and unavailability caused by a Force Majeure event.
"System architecture design targets are higher, and long term, it is expected that stable in-service performance may in some cases exceed 99 percent".
Force Majeure is a legal clause that exempts NBN Co from responsibility in circumstances beyond their control – such as a so-called 'Act of God'.
NBN Co said it would build geographic redundancy into its B2B infrastructure and hoped ISPs would do the same.
"Similar deployment architectural considerations from Access Seekers will support very high availability for reliable delivery of messages between organisations," NBN Co said.
NBN Co has also – for the first time – put performance targets on its B2B system, from the time a message enters the gateway to the time it exits for the return trip back to the ISP.
For example, it wants an ISP looking up the address of a potential NBN customer to pass through its systems in under five seconds.
Order fulfillment should take less than five minutes. Trouble ticket lodgment should occur in under ten seconds, according to the NBN documents.