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Packet Optical Transport
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The last few years have seen the development of new technologies such as Carrier-class Ethernet to a stage beyond speculation, and
into network deployment. SDH (Synchronous Digital Hierarchy) / SONET (Synchronous Optical Network) have seen a rebirth, and are no more talked of as Legacy Technology. It is
increasingly become clear, that rather than replace each other, the above technologies will need to inter-operate with each other.
The large installed base of SDH/SONET and increasing demand for data services, forced the vendors to work towards Data-optimizing their SDH/SONET Networks. This Next-generation
SDH/SONET, which came into existence around 2002, had 3 important components: Virtual Concatenation (VCAT) (ITU-T G.707/Y.1322 and G.783), Link Capacity Adjustment Scheme (LCAS)
(ITU-T G.7042/Y.1305) and Generic Framing Procedure (GFP) (ITU-T G.7041 (2001) & ANSI T1.105.02 (2002))
As enterprises are looking for network connectivity beyond the walls of their LANs, Metro Ethernet becomes an obvious choice from a technical and cost perspective. Around 2005, the
Ethernet capabilities of SDH/SONET were taken to the next level when packet processing or switching functionality was integrated within the next-generation SDH/SONET equipment. This
combination of next-generation SDH/SONET and Ethernet service-level traffic management in a single platform, gave service providers the ability to migrate to an integrated service
model. Point-to-point as well as advanced point-to-multipoint, and multipoint-to-multipoint Ethernet/IP services such as Video, VoIP (Voice over IP) and Virtual Private Networks can
be delivered over existing SDH/SONET networks – incrementally, and in parallel with traditional TDM services such as voice and private lines. |
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