Telecommunications resilience in the UK: the ‘last mile’ is the weakest link
It is widely recognised that the UK PSTN (Public Switched Telephony Network) infrastructure is one of the most reliable infrastructures in the world with examples of services being quoted as having ‘five 9s availability’: i.e.99.999% availability equating to some 5 minutes downtime across the whole network over a twelve month period. Unfortunately, the same cannot be said for the connectivity, the telephone circuits, installed by the various Tier I Providers between their respective Local Exchanges. This infrastructure is located on the periphery of the PSTN and the end-user customer’s premises: commonly referred to as ‘the last mile’. Why is this a weak link in the system? Because the Tier I Providers simply cannot be held responsible for the integrity of these circuits. They invariably run in 5cm diameter pvc ducts and are usually located only some 15cm beneath the pavement surface where they are very susceptible to damage caused during road works and/or by heavy vehicles driving over badly consolidated excavations. Add to this vulnerability any number of reasons why it is not always possible to gain access to conventional offices or other places of work (including severe weather conditions, fire, police cordons, transport strike etc.) and it can be easily appreciated that it is the ‘last mile’ that needs very careful thought when considering the implementations for business continuity plans. The vulnerability of the last mile is highlighted in the excellent ‘Good Practice Guide Telecommunications Resilience’ prepared by the NISCC (National Infrastructure Security Co-Ordination Centre) in conjunction with the leading network providers and the Civil Contingencies Secretariat, first published in May 2004 and subsequently up-dated in March 2006. This states: “One of the principal areas of concern is the route congestion between customer premises and local exchange or Point of Presence (POP). This is of particular concern in built up or high density areas such as the City of London and is often a classic example of a single point of failure. Due to the historical position of BT as the incumbent telecommunications Provider before privatization, the “local loop” or last mile in the majority of cases is a BT asset. Local Loop Unbundling (LLU) obliges BT to allow other Providers use of these assets resulting in third party Providers selling circuits over the same cable routes as BT. As there is no requirement for either Provider to discuss the use of these circuits with the other, they may be unaware that the customer possibly intended the circuits to be separated. In this way the customer may be lulled into a false sense of security. True separation, or separacy, as it is known, in this example would have been possible by asking one Provider for two separate circuits. It is worth noting here that buying two similar circuits from the same Provider may actually be more economical than buying one circuit each from two Providers. This in turn, however raises concern over the dependency on a single provider…” This document also incorporates two extremely relevant questionnaires – one designed to ask an organization’s provider and the other to address key issues internally within an organization – which will go some way to identifying the level of preparedness for a telecoms failure. Putting this into the context of business continuity planning, the Civil Contingencies Act 2004 requires Category 1 responders to maintain plans to ensure that they can continue to exercise their functions in the event of an emergency, so far as is reasonably practicable. The business continuity management duty in the Act relates to all the functions of a Category 1 responder, not just its civil protection functions. Hence the legislation requires Category 1 responders to maintain plans to deal with emergencies and put in place arrangements to warn and inform the public in the event of an emergency. But it also requires them to make provision for ensuring that their ordinary functions can be continued to the extent required. There are various options available for providing the last mile with greater resilience, connectivity-wise. These range from the provision of ‘dual parenting’ (involving the provision of duplicate circuits from a second local exchange) to varying degrees of ‘diverse routing’ (again, involving the provisioning of duplicate circuits but this time being delivered from the same exchange). However, all of these options carry a significant additional cost and the availability of these additional services may vary from provider to provider. Care should also be taken to ensure that when considering the adoption of the diverse routing option that the provider is able to guarantee that the duplicate circuit(s) will follow a completely separate route from the local exchange to the customer premises from that of the original circuit to ensure that the necessary additional resilience is actually provided. However, in order to provide a truly resilient solution for protection against a failure of the last mile – which should include, not only protection against cut/failed circuits running between the local exchange and the organization’s premises, but also a failed premises-based PBX or, more importantly, the inability of some, or all, of an organization’s employees to gain access to their normal place of work for any number of reasons – it is necessary to look beyond the concept of simply providing additional resilience to the telephone circuit connectivity. This was clearly in evidence during the floods of 2007 when it was simply impossible to access Humberside Police HQ in Hull and in Carlisle in 2005 when the main Carlisle City Council offices, local police station and fire station were all rendered inaccessible as a result of rising flood water forcing the council to relocate some of their key personnel to their recovery site located on higher ground. Unfortunately, in both of these instances, no provision had been made to recover, by re-routing, their incoming calls to alternative DDIs in their designated recovery sites. The instantaneous and seamless recovery of all inbound calls directed to any organization’s individual geographical DDI numbers (local numbers starting 01 or 02) is seen as being absolutely key to any organization – and particularly relevant to Category 1 stakeholders who have specific responsibilities under the Civil Contingencies Act. The ability to quickly recover, by re-routing, individual geographic DDI numbers is not something that the Tier I Providers specialise in providing but there are a select few specialist telecoms technology companies who have focused on the delivery of telecoms business continuity, including my company, GemaTech, that can also provide network based secure voice recording of all inbound and outbound calls, together with the recording of all inbound and outbound calls following an invocation. The provision of voice recording is seen as a great advantage in the aftermath of any outage when it is necessary to investigate what actually happened during and following any outage. These solutions are also available via in-house providers as well as under existing local purchasing framework agreements. What is vitally important, however, is the ability of any telecoms recovery solution to be able to link into, re-route calls to, and receive calls from, both satellite phones – made available to all qualifying Category 1 Stakeholders via a Civil Contingencies Secretariat initiative – and also Airwave handsets to ensure full interoperability between Local Resilience Team members and related emergency services. Also vitally important is the ability to make partial invocations, to allow for the fact that only some of an organization’s employees are unable to travel to work on a specific day. In those circumstances it should be possible to re-route only those calls to ‘missing’ members of staff to their homes or alternative places of work whilst allowing all other inbound calls to all remaining members of staff through to their normal desk positions. Alternatively it may be necessary, on occasion, to invoke a business continuity plan for a certain section of the building because of some localised problem affecting a small number of employees. Flexibility is the key. An example of a fully resilient last mile is shown here. This illustrates, in general principle, how technology can be deployed on the periphery of the resilient PSTN by locating it in the sanctity and security of the local exchange – with the added benefit that many exchanges now having been upgraded to resist flooding, fire and terrorist attack. Author: Graham Chick is chief executive of GemaTech. For more information on GemaTech’s products and applications email ccentral@gematech.com or visit www.gematech.com
•Date:19th June 2009• Region:UK •Type: Article •Topic: Telecoms continuity |
