Diversity Planning

Communications Options consultants are experts at designing networks that are protected from failure by the incorporation of engineered diverse paths. There are at least five types of network diversity. An insufficient amount of any of the five types of diversity can put a company at risk of catastrophic failure in its telecommunications network.

Building Entrance Diversity

Building entrance diversity is achieved when a business has more than one ISDN30 circuit, and the circuits enter its building at different locations. Building entrance diversity is an extension of route diversity. Instead of designing a diverse route back to the exchange, you ensure that the circuits take diverse routes into the building. This ensures against building faults such as fire, engineering work that cuts through telephone lines, etc.

Local Loop Diversity

Often, the cause of a failure in telecommunications lines results from construction work that cuts through the lines in the ground. This can result in a loss of telecommunications services. Circuit diversity cannot prevent this disruption, unless the circuits take different routes back to the telephone exchange. Local Loop diversity ensures that a cut through a group of circuits does not completely nullify a company’s ability to make calls, since it will have another circuit travelling by a separate route to the telephone exchange.

Exchange diversity

All telephone lines from a client’s site, whether terminating on a telephone system or supplied via Centrex, will originate at a telephone exchange. No matter how complex a client’s telecommunications set up, a failure of the telephone exchange will result in a complete loss of telephone access.

To circumvent this possibility, large corporate locations should have circuits that terminate at two different telephone exchanges. This option may not be available for large offices that are outside of large metropolitan areas.

Circuit Diversity

Businesses use ISDN30 ubiquitously to make and receive the majority of their voice calls. A failure in an ISDN30 circuit can leave a business with a substantially reduced ability to make and receive calls.

Installing two ISDN30 circuits can help to insure against this possibility. A failure in one circuit would leave the second circuit still able to make and receive calls. There is one caveat, however. Carriers will often put more than one ISDN30 on the same circuit, in which case a failure in the circuit would disable both ISDN30s. Companies should ensure that each ISDN30 is carried on a separate circuit. Companies should also ensure that each circuit is able, in the event of a failure in one of the circuits, to be able to handle both incoming and outgoing calls.

For locations that only require one ISDN30 to handle the total voice traffic, installing a second ISDN30 can seem extravagant. One way around this is, when installing ISDN30 service, to request 31 channels (one circuit with 15 channels and one circuit with 16 channels).

Carrier Control Network Diversity

A fault in the carrier control network can disable calling in a business that has exchange, circuit, route, and building entrance diversity substantially built out. If BT’s network fails, failure to have a circuit supplied by an alternate carrier will mean the loss of telephony service.

Businesses that have more than one ISDN30 circuit should have the second circuit provided by an alternate carrier. The alternate carrier providing the circuit must have its own network, however, to achieve carrier control network diversity. Many carriers in the UK market supply ISDN30 to carry outgoing traffic, but are merely reselling a BT circuit. In this instance, having two circuits supplied by alternate carriers provides no diversity if both circuits terminate on the same carrier network.

While incorporation of diversity into a network will add cost to the design, the cost is usually insignificant compared to the business costs associated with catastrophic failure of the company’s telecommunications facilities.

Communications Options undertakes consulting on engineered diverse network planning for some of the largest networks in the world including the networks of two of the largest financial institutions in the world and one of the largest oil companies.

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