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198 Chapter 8

Figure 8-11
Combining services INTERNET
onto a DS-3 and
then multiplexing
onto SONET
OC-12
DNS
Secondary DNS
Core Router
Radius/Security

PBX or
Key System
OC-3

T1 Telephone Company
Hub
T1 Voice Switch
10 Mbps T3
Channel Bank Digital Cross Connect
(DACS)

These can all be combined at the local loop and then carried
through a channel bank or multiplexer to the LEC office.At the LEC
office, the T-1s can be dropped off into the voice switch for circuit-
switching needs (dial-up voice). Meanwhile, the data continues
through a digital cross-connect system to a core router. This will
enable Internet access at 10 Mbps. Combinations of such services are
almost endless. The common denominator is the use of high-end
multiplexers in the LEC office to bundle the services onto a fiber-
based architecture such as SONET/SDH.

Alternative Approaches to Multiple

Services Delivery

As we continue to escalate the speed of data networks, we hear many
arguments about the best way to carry the traffic. The Internet Pro-
tocol (IP) is now the most common form of data that we need to send