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The Road to 100G Networking

Neeraj Gulati
Tuesday, December 30, 2008
Neeraj Gulati
Rapid movement within the information age continues to create challenges in the communication landscape. Application requirements and user demand are driving the bandwidth growth across backbone networks, well past the single 10G capacity to support multiple 10G connections.

Additionally, the networking landscape is shifting toward Ethernet-based infrastructures as the demand for high-bandwidth services increases, resulting in a lower cost infrastructure that supports 10G connectivity. With data demands increasing exponentially, the current generation of 10 Gb/s networking has become insufficient to meet tomorrow’s networking needs. This increased demand follows a pattern established with the adoption of 40 Gb/s standards for transport in the late 1990s, and the 40 Gb/s IP router and Dense Wavelength Division Multiplexing (DWDM) field trials in around 2004. Although 40 Gb/s service is entering a growth phase, it is insufficient for many future network applications. Currently, the industry is working to standardize 100G technologies to take advantage of greater scalability and a more efficient convergence of optical data rates. The result of this push may restrict the use of the 40G technology to limited areas of network capacity until 100G is commercially available. For these reasons vendors, industry standards bodies, and network operators favor 100 Gb/s transport speed for future networking. This paper outlines the requirement for 100G technologies and introduces the underlying fundamental technologies that enable the support of 100G.

Convergence of Transport and Ethernet

As networks migrate to IP packet-based networks, transport and Ethernet data rates experience a paradigm shift. Ethernet rates historically have increased by a factor of ten and are currently defined up to 10 Gb/s. Alternatively, SONET/SDH/Optical Transport Network (OTN) rates, currently defined up to 40 Gb/s, traditionally increased by a factor of four; the convergence began at 10 Gb/s. With recent developments, this convergence continues at 40 and 100 Gb/s, as shown in Figure 1.

The emerging standards support this convergence and provide the framework for next-generation networking. Currently, 40GbE — originally proposed for data center aggregation and enterprise computing — is likely to be used in the transport network, an increase by a factor of four instead of the traditional factor of ten for Ethernet. For backbone transport networks, 100 Gb/s is proposed for an increase of two and a half times on the previous 40 Gb/s SONET/SDH/OTN rate, instead of an increase by four times which is the previous rate. This convergence between transport and Ethernet, shown in Figure 2, is changing the networking landscape rapidly. Additionally, support for machine protocols, such as Infiniband over the Wide Area Network (WAN), are best suited for 100 Gb/s speeds, potentially driving the requirements for 100 Gb/s networking as well.

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