At
the time, ATM encapsulation was a logical choice because of a large number of ATM
links in the backbone and metro networks at the time and its suitability for multiple
protocols. The PON architecture was supposed to provide a cost-effective structure for
service delivery. The APON format used by FSAN was accepted as an International
Telecommunications Union (ITU) standard (ITU-T Rec. G.983). However, the APONs
failed to meet original expectations since ATM-based cards and switches are far more
expensive when compared with Ethernet equipment, and currently the manufacturing
lots are decreasing.
Ethernet PONs (EPONs) were initiated and developed by start-up companies believing
that the APON standard is an inappropriate solution for the local access loop because of
its lack of inherent video broadcast capabilities, insufficient bandwidth, complexity and
hardware costs. Adoption of first gigabit Ethernet in enterprise and local area networks
(LANs), as well as the increasing pace of deployment of 10 Gbps Ethernet equipment
first in wide area networks (WANs) and now also in LANs as the port costs decrease
seem to confirm that EPON is the solution for linking the Ethernet-centric world of
local networks with the transport layer of MANs/WANs.
Pages:
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419