Like WANs, MANs
aggregate traffic from feeder networks; however, the aggregation
level is less in a WAN, and direct connection of high-performance
end users is more common. The fiber link infrastructure of the MAN
is expected to be similar to the WAN with links made up of fiber
bundles and WDM technology used on the links.
Because of the
shorter distances involved, links are of higher quality, and there
is more control over the topology, with rings, buses, hubs (stars),
and trees being common choices (Fig. 10). These topologies have
well-defined synchronization points, which enables ON service
options based on time-sharing wavebands that could not be provided
in the WAN.
Physical architecture of the WDM optical metropolitan access network.
Figure 11 - A
functional diagram of the MAN intelligent access node.