IP Centrex: The Next Level In Improving Disaster Recovery

BY KELLY STILL

Deploying an IP Centrex solution can be a significant and cost-effective means of improving a disaster recovery plan using today's highly reliable telephone system.

The industrialized world's Public Switched Telephone Network (PSTN) sets the standard for reliable operation and is engineered for levels of uptime few other systems in the world can match. Yet recent events have illustrated that telephony service from traditional circuit switches, even when based on the incredibly robust Class 5, is vulnerable to catastrophic trauma to a single switch complex. Such traumatic events include fires, floods, and outright destruction of central office (CO) facilities.

After the September 11, 2001 attack in Lower Manhattan, many businesses lost their telecommunications capabilities because they were dependent on fiber optic lines that connected to Verizon's CO facility. The destruction of the World Trade Center took out this CO and as a result caused weeks -- and for some, months -- of service disruption.

Since this catastrophic event, the importance of telephony disaster recovery as a good business practice is a concern, and for many, a necessity.

The value of leveraging the IP network is self-evident: it is a distributed network and supports rapid relocation of gateways and end-user access points if disaster strikes. Consequently, using IP Centrex for disaster recovery is an appealing solution. To eliminate a single point of failure in the access network, IP Centrex can be deployed along with a redundant (multi-path) packet network. This replaces simplex circuit-based access networks, avoiding a single point of failure.

In addition, virtual office deployment brings an element of disaster recovery that is not possible with any TDM system.

Improving service reliability and disaster recovery with IP Centrex can be broken into three key components:

1. The Class 5 switch;
2. Redundant, multi-path data networks; and
3. Fluid access points for virtual offices to improve work site recovery.

1. The Class 5 Switch
The IP Centrex model takes full advantage of the feature set and reliability of the Class 5 switch. Centrex users, who get their basic phone service from Class 5 COs, consistently rate "reliability" as one of the clear advantages of the service.

Reliability in the Class 5 switch is achieved not only because of fully redundant hardware (there are several other communications platforms that can lay claim to fully redundant, NEBS 3-compliant hardware), but also because of the software. This software has been tested through billions of hours of actual user traffic, extensive carrier testing and rigorous proving in vendor labs.

Indeed, no other distributed communication software system has ever been shown to be as reliable as the Class 5 switch, which operates at 99.9999 percent reliability. IP enabling this communications work horse extends that reliability to any office within the reach of a managed IP connection.

Nor have implementations of IP PBX systems on the customer premise been as secure as a CO-based Class 5 switch. If a catastrophic event destroys the company site, these telecommunications systems go down. It is for just that reason that phone companies place their Class 5 switches in secure buildings with power supply backups, earthquake and fire suppression, and locations on high ground to avoid flooding. Such secure facilities are not easily duplicated on company premises.

2. Redundant, Multi-Path Data Networks
Instead of using traditional circuit-based access networks to transport voice to a specific twisted copper wire in a single office location, IP Centrex uses a packet-access infrastructure. Properly designed and implemented, the use of fully-meshed data networks offer significant disaster recovery and service reliability advantages over circuit-based networks.

Because data networks are logical rather than physical in design, they can handle many situations -- including disaster recovery -- more quickly and easily than circuit-based equipment. When properly engineered and configured, data networks can provide a level of route redundancy that exceeds the TDM world. Multi-path designs can utilize redundant paths without human intervention (in other words, they can be self-healing). This design enables a data network to approach 100 percent uptime. The idea of self-healing networks with multiple routing paths offers obvious advantages when dealing with a variety of disaster scenarios.

Data networks also have advantages in cases where a disaster requires rapid facilities replacement. Such a network can provide voice communications and Internet connectivity with minimized downtime.

To accelerate the disaster-recovery process, a network deploying IP Centrex must be pre-engineered. Detailed contingency plans with equipment provisioning parameters and pre-positioned IP addresses that are easily implemented in a straightforward manner are a key to rapid recovery.

Remote management of an IP Centrex solution is seamless, speeding the reinstatement of a system that has experienced trauma. Much of the logical network modification can be done remotely with the proper network in place; thus a network could be configured from anywhere in the world.

Similar to the CO environment, power availability for these networks is easy to back up. Data-networking equipment can be powered by AC or DC power as well as uninterruptible power supplies. Equipment can readily be located in homes and office buildings in case of an emergency, due to the flexibility of power supplies.

3. Fluid Access Points For Virtual Offices To Improve Work Site Recovery
Fire, floods, and other traumas can easily render a workplace uninhabitable. Implementing IP Centrex simplifies a major element of comprehensive recovery after catastrophic events at a specific work site.

IP Centrex is inherently easy to re-deploy rapidly to alternate office sites. Voice communication can be carried on the same network that is being developed for data recovery. Once a data connection back to a managed LAN or WAN is established, office IP phones can be immediately connected and used. Such flexibility is an advantage not only in disaster recovery, but in everyday office reorganization.

One familiar value-producing application for IP Centrex is the ease of enabling the enterprise model of teleworkers. Teleworkers gain access to their office telephony system while working remotely, even from home. The telework advantage from a disaster recovery recovery standpoint is even more compelling. As long as the worker has data connectivity to the company network (or a rapidly-deployed post-disaster subset of the original), they have full access to the communication environment. A company's workforce can be up and running even before alternate office facilities are brought online.

In a disaster recovery situation, employees can still be fully productive while working from their homes. An IP Centrex solution will also ensure that the original directory numbers for the business and all employees remain unchanged. Thus, a strategy of geographic diversification is made possible, avoiding an inability to recover communication due to trauma to any specific location. A distributed array of smaller regional work sites, including a widely-distributed pool of teleworkers, solves the problem.

Conclusion
A well-designed IP Centrex deployment can provide levels of protection from facility destruction that are not available in any TDM-only solution. The system can be deployed with no single point of failure -- all the way out to the end user. Further, the ability to access the service from any location through a data connection enables service mobility that provides excellent protection from the risks affecting availability of the work site.

Kelly Still is director of marketing technical services for Lucent Technologies. Lucent offers service providers advanced network-based solutions, including circuit and packet switching, voice over Internet protocol (VoIP) and IP Centrex, call center and integrated access products.