Optical Networks - _6_5 IP_78

Optical Networks - _6_5 IP_78 - 6.5 IP 411 MPLS, PBB-TE...

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6.5 IP 411 MPLS, PBB-TE connections can be routed to efficiently utilize network bandwidth or to achieve certain performance criteria such as maximum latencies, minimum throughput, or maximum loss rates. Note that resources can be provisioned to guar- antee service-level agreements (SLAs) for these connections. PBB-TE also supports provisioning backup tunnels for protection. PBB-TE disables the spanning tree protocol, broadcasting, flooding, and the learning aspect of switched Ethernet routing. This eliminates some of the dynamic, self-organizing, and complex aspects of the Ethernet protocol, making it simpler, more stable, and more controllable. Besides PBB-TE, survivability mechanisms have also been developed for Ethernet to support carrier grade service. These mechanisms are described in Section 9.3.2. 6.5 IP IP (Internet Protocol) is by far the most widely used wide-area networking technology today. IP is the underlying network protocol used in the all-pervasive Internet and is equally important in most private intranets to link up computers. IP is a networking technology, or protocol, that is designed to work above a wide variety of lower layers, which are termed data link layers in the classical layered view of networks (Section 1.4). This is one of the important reasons for its widespread success. Figure 6.19 shows IP within the layered architecture framework. The traditional data link layers over which IP operates are Ethernet and the point-to-point protocol (PPP). IP operates over other low-speed serial lines as well as high-speed optical fiber lines using well-known data link layer protocols—for example, high-level data link control (HDLC). Several layering structures are possible to map IP into the optical layer. The term IP over WDM is commonly used to refer to a variety of possible mappings shown in Figure 6.20. Figure 6.20(a) shows the packet-over-SONET (POS) implementation. Here, IP packets are mapped into PPP frames and then encoded into SONET frames for transmission over a wavelength. Figure 6.20(b) shows an implementation using Gigabit or 10-Gigabit Ethernet as the underlying link (media access control) layer and Gigabit/10-Gigabit Ethernet physical layer (PHY) for encoding the frames for transmission over a wavelength. We will study the implications of these different approaches in Chapter 13.
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Optical Networks - _6_5 IP_78 - 6.5 IP 411 MPLS, PBB-TE...

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