ATM and Frame Relay–Switching Equipment

The 802.16 standard supports ATM as well as IP, and at least one broadband wireless manufacturer,
Alvarion, supports frame relay. To that extent, ATM- or frame relay–based services are an
option for the broadband wireless operator. Normally, to provision either service, a separate
dedicated switch is required; however, a number of so-called godbox multiservice-switching
platforms are on the market that handle both types of traffic within the confines of a single box.
For an illustration of how an ATM switch fits into a wireless public network, refer to Figure 6-4.
This architecture characterized the first generation of broadband wireless services and is still
permitted in the 802.16 standard. Investing in an ATM switch or frame relay access device (FRAD) is generally not warranted
in a broadband wireless network today. Frame relay services are legacy and relatively inflexible
compared to IP since support for multimedia is not well developed. ATM, while it provides
excellent QoS for a wide range of services, is bandwidth inefficient. Moreover, the ATM at the
desktop enterprise equipment that would justify the use of this protocol at the central office
has ceased to be manufactured. Within the 1998–1999 time frame the possibility existed that
ATM would indeed become the universal platform that its creators always intended it to be, but
the extremely high cost of the equipment precluded significant penetration in the enterprise,
let alone in the consumer residential market. ATM continues to be widely used in long-haul
networks and will be for many years to come. It is also extensively used in DSL aggregation and,
somewhat curiously, in the FireWire connections used in consumer multimedia applications.
Furthermore, most first-generation Local Multipoint Distribution Service (LMDS) millimeter
microwave equipment was ATM based, as was some first-generation lower microwave pointto-
multipoint hardware. But beyond these established niches, ATM is not experiencing growth
or expansion. In any case, ATM switches remain extremely expensive devices priced in the tens
of thousands of dollars. I cannot conceive of how such an allocation of resources could possibly
be judicious in a metropolitan broadband network.