"Previously, we were in two separate buildings, in Albert St and Wyndham St, the legacy Coopers & Lybrand and Pricewaterhouse buildings. Both had old equipment which we knew we were going to replace, as we were looking to move.
"Albert St was still running token ring, which we were going to replace and move to a fully ethernet environment -- Wyndham St was ethernet."
Running the two different network architectures carried the associated issues of people moving between buildings and changing hardware. "The decision was made to introduce something new, totally new equipment," he says.
"We wanted to go for gear that was very scalable, something that was going to be able to handle everything we could see coming in the future, for example, video to the desktop and IP telephony."
While PwC has neither of those functions yet, "we wanted to put ourselves in a position where we felt that if the technology has got to an economic point, we had the infrastructure to install it".
Two Foundry BigIron layer three switches form the core of PwC's national network and it also includes FastIron layer 2 and 3 switches and Foundry's IronView network management software.
The network provides 100Mbit/s to the desktop.
At present, the switches aren't being used beyond layer three.
"We're not using them to their full capability -- one of the options available to us if the need arises is that we'll be able to administer another site with the Foundry tools."
The gear won't be replaced in the near future, Cairncross says.
"Given our discussions with Foundry to date, the updates available to the technology and the underlying management software, we believe the equipment will be around in five years' time."
Cairncross says the concept of switches and routers is "already blurred and the two will become significantly closer."
An upgrade to 10Gb/s would be possible, "but we haven't discussed it yet.
"We have a 2Gbit/s backbone through the whole building and the amount of traffic we're getting at the moment isn't putting pressure on it yet."
Another significant Foundry deployement in New Zealand is at Weta Digital, where BigIron and FastIrons have been used in the creation of special effects for The Fellowship of the Ring and The Two Towers.
The BigIron switches give gigabit ethernet over copper to servers and users at high-end workstations.