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ISBN: 978-1-119-48615-2
About the Author
James Aweya was a Senior Systems Architect with the global Telecom company Nortel, Ottawa, Canada, from 1996 to 2009. His work with Nortel involved many areas, including the design of communication networks, protocols and algorithms, switches and routers, and other Telecom and IT equipment. He received his B.Sc. (Hons.) degree in Electrical & Electronics Engineering from the University of Science & Technology, Kumasi, Ghana; M.Sc. in Electrical Engineering from the University of Saskatchewan, Saskatoon, Canada; and Ph.D. in Electrical Engineering from the University of Ottawa, Canada. He has authored more than 54 international journal papers, 39 conference papers, 43 technical reports, and received 63 U.S. patents, with more patents pending. He was awarded the 2007 Nortel Technology Award of Excellence (TAE) for his pioneering and innovative research on Timing and Synchronization across Packet and TDM Networks. He was also recognized in 2007 as one of Nortel's top 15 innovators. Dr. Aweya is a Senior Member of the IEEE. He is presently a Chief Research Scientist at EBTIC (Etisalat British Telecom Innovation Center) in Abu Dhabi, UAE, responsible for research in next-generation mobile network architectures, timing and synchronization over packet networks, indoor localization over WiFi networks, cloud RANs, software-defined networks, network function virtualization, and other areas of networking of interest to EBTIC stakeholders and partners.
Preface
This book discusses the design of multilayer switches, sometimes called switch/routers, starting with the basic concepts and then on to the basic architectures. It describes the evolution of multilayer switch designs and highlights the major performance issues affecting each design. The need to build faster multilayer switches has been addressed over the years in a variety of ways and the book discusses these in various chapters. In particular, we examine the architectural constraints imposed by the various multilayer switch designs. The design issues discussed include performance, implementation complexity, and scalability to higher speeds.
The goal of the book is not to present an exhaustive list or taxonomy of design alternatives but to use strategically selected designs (some of which are a bit old, but still represent contemporary designs) to highlight the design philosophy behind each design. The selection of the example designs does not in any way suggest a preference for one vendor design or product over the other. The selection is based purely on how representative a design covers the topics of interest and also on how much information (available in the public domain) could be gathered on the particular design to enable a proper coverage of the topics. The designs selected tend to be representative of the majority of the other designs not discussed in the book.
Even today, most designs still adopt the old approaches highlighted in the book. A design itself might have existed for some time, but the design concepts have stayed pretty much alive in the telecommunication (Telecoms) industry as common practice. The functions and features of the multilayer switch have stayed very much the same over the years. What has mainly changed is the use of advances in higher density manufacturing technologies, high-speed electronics, faster processors, lower power consumption architectures, and optical technologies to achieve higher forwarding speeds, improved device scalability and reliability, and reduced implementation complexity.
As emphasized above, these design examples are representative enough to cover the relevant concepts and ideas needed to understand how multilayer switches are designed and deployed today. The book is purposely written in a simple style and language to allow readers to easily understand and appreciate the material presented.
James Aweya
Etisalat British Telecom Innovation Center (EBTIC)
Khalifa University
Abu Dhabi, UAE
Introduction to Switch/Router Architectures
1.1 Introducing the Multilayer Switch
The term multilayer switch (or equivalently switch/router) in this book refers to a networking device that performs both Open Systems Interconnection (OSI) network reference model Layer 2 and Layer 3 forwarding of packets (). The Layer 3 forwarding functions are typically based on the Internet Protocol (IP), while the Layer 2 functions are based on Ethernet. The Layer 2 forwarding function is responsible for forwarding packets (Ethernet frames) within a Layer 2 broadcast domain or Virtual Local Area Network (VLAN). The Layer 3 forwarding function is responsible for forwarding an IP packet from one subnetwork, network or VLAN to an another subnetwork, network, or VLAN.