[LINK] Is the NBN Ready for Extreme Weather?

[Paul Brooks]

Tom - you speak as if the NBN and the mobile phone networks are not currently as reliable as the old PSTN is. Do you know of any studies which show this?

Underground cables, both fibre and copper, are typically washed away and severed during floods. Overhead cables are often severed during bushfires (if on wooden poles) and vehicle accidents. Cockatoos eat overhead cables, rats eat underground cables.

(pedantry on)
The PSTN is a telephone service, which comprises the telephone switches in exchanges and the customers handset. However, it appears you are describing the CAN (Customer Access Network), which is the collection of wires and fibres over which the PSTN is carried. The PSTN is also carried over the NBN and mobile networks. Even VoIP is part of the PSTN if it can call other E.164 numbers on other networks.

You are talking primarly about the reliability of the copper CAN, as well as a little bit on the PSTN switches in the exchanges when you speak of power reliability.
(pedantry off)

The NBN fibre network is carried on exactly the same poles and underground conduits as the CAN, and includes fibre loops for redundancy against cable cuts in certain segments, is a star network susceptible to cable cuts in the same sections as the copper CAN. The electronics in the echange-equivalents are backed up by batteries and generators. There is no reason to expect the NBN is going to be less reliable than the PSTN or the CAN.

The mobile phone networks, from the exchanges out to the base station antennas, are also driven by redundant fibre loops and have backup batteries. It also has the relability characteristic that a handset usually has multiple basestations it can connect to if one fails, which the copper CAN does not have. Arguably the mobile phone networks, for this last reason alone, should already be more reliable than the old CAN.

Most people, when talking about mobile reliability, confuse the issue by including handset-battery-runs-out and wireless-signal-fades issues, which are both out of the control of the carrier and network - if people would all just stand still.
 
Paul.



-------- Original Message --------
From: Tom Worthington <tom.worthington at tomw.net.au>
Sent: Thu Dec 06 08:30:23 AEST 2012
To: "link at mailman.anu.edu.au" <link at mailman.anu.edu.au>
Subject: [LINK] Is the NBN Ready for Extreme Weather?

Frank Yardley from the NCCARF Emergency Management Network at RMIT 
University pointed out a Senate Inquiry into preparedness for extreme 
weather events. It invites submissions on the preparedness of major 
infrastructure, including telecommunications: 
http://www.aph.gov.au/parliamentary_business/committees/senate_committees?url=ec_ctte/extreme_weather/tor.htm

My suggestion would be that as a matter of policy, the combination of 
the NBN and mobile phone networks should be made as reliable as the old 
PSTN was. This should not be just for voice calls but for data as well.

The Public Switched Telephone Network (PSTN) used underground cables and 
switching centers with backup power supplies. The system would therefore 
work during power failures, floods, cyclones, fires and other disasters. 
The NBN relies on mains power in the customer's premises to function. 
While there is provision for battery backup where a voice service is 
provided, many people will be using VoIP via the Internet, where no 
battery backup is provided. Also the fiber optic cable may be more 
vulnerable to damage, where it enters the customer's premises. Mobile 
mobile phone towers may be more vulnerable to damage in disasters.


-- 
Tom Worthington FACS CP, TomW Communications Pty Ltd. t: 0419496150
PO Box 13, Belconnen ACT 2617, Australia  http://www.tomw.net.au
Liability limited by a scheme approved under Professional Standards
Legislation

Adjunct Lecturer, Research School of Computer Science,
Australian National University http://cs.anu.edu.au/courses/COMP7310/
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