
12.3 EVOLUTION OF METRO NETWORK
ARCHITECTURES
12.3.1 Network Architecture Drivers
In an environment of an ever increasing richness of services, at progressively
higher bit rates, but with a price point that must grow slower (or even decline) than
their required bandwidth, serv ice providers must build very efficient networks—
with the lowest possible Capital expenditure (CAPEX), as well as low operational
costs (OPEX).
CAPEX can be optimized by the following means:
• Allowing for as much bandwidth oversubscription as possible, while still
respecting the quality of service (QoS) customers are expecting. This cannot
be achieved by connections with fixed ...