Aggregating these figures over large user
populations gives genuine multigigabit requirements, and hence many VoD servers
already support Gigabit and 10 Gigabit Ethernet interfaces.
In response to this growth, nearly all cable operators have moved to HFC setups,
using fiber to interconnect master head-ends with dispersed local hubs. Meanwhile incumbents
are actively pursuing the residential video market to offset declines in longdistance
voice. Here video delivery architectures are being overlaid on top of entrenched
metro/edge fiber-plants. Namely localized video switching offices (VSO) at smaller edge
ring sites are being interconnected to video hub offices (VHO) at larger metro core/
regional hubs. The former sites connect to DSL access multiplexers (DSLAM) or PON
optical line terminals (OLT) units for last-mile delivery. Meanwhile, the latter sites
house large VoD servers. Overall EoWDM is ideal for native packet-video backhaul
over existing cable/incumbent fiber plants. Scalability is the paramount concern here,
and only multi-channel DWDM can realistically provision large head-end flows with
thousands of homes crossed. Moreover, because head-end/hub or VSO/VHO locations
are largely fixed, lower-cost static OADM setups are also very feasible.
Pages:
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564