Telecommunications network providers and users are concerned about the single point of failure in “the last mile,” which is the single cable from the network provider’s last switching station to the customer’s premises. How can a customer protect against that single point of failure? Comment on whether your approach presents a good cost-benefit trade-off.

Question

What will be an ideal response?

Answer 1

Generally, the last mile is not protected, at leastnot for normal (residential) customers. Plain telephone service typically connects two pairs of wires to each house, for two reasons: to have a spare pair in case ofa failure in the first and (more important) to make for an easy upgrade to two telephone lines if the customer expands a service request.

Compensating for a failure in the last mile requires redundancy, from the last switching point to the endpoint. But that implies two cables on different poles (to protect against a windstorm’s severing a cable) or in two underground paths (to protect against the ubiquitous nonmalicious backhoe operator). Such full redundancy is expensive unless high availability is truly required.