{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Optical Networks - _Chapter 10 WDM Network Design_116

Optical Networks - _Chapter 10 WDM Network Design_116 - 10...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
10 chapter WDM Network Design I n previous chapters, we learned that the optical layer provides high-speed circuit-switched connections, or lightpaths, between pairs of higher-layer equip- ment such as SONET/SDH muxes, IP routers, and Ethernet switches. The optical layer realizes these lightpaths over the physical fiber using elements such as optical line terminals (OLTs), optical add/drop multiplexers (OADMs), and optical cross- connects (OXCs). We called a network using such lightpaths a wavelength-routing network. In this chapter, our goal is to study how to design a wavelength-routing network. This involves studying not only how to design the optical layer but also how the higher-layer SONET or IP network is to be designed because the design of the two layers is closely coupled. We illustrate with an example. Example 10.1 In Figure 10.1(a), there are three nodes labeled A, B, and C, connected by WDM fiber links. For simplicity, assume the traffic generated is in the form of IP packets from routers located at these nodes. Similar examples hold if the higher layer consists of SONET/SDH muxes. For concreteness, also assume that all router interfaces operate at 10 Gb/s, which is also the transmission ca- pacity on each wavelength on the WDM links. Now suppose, based on estimates of the IP packet traffic, 50 Gb/s of capacity is required between all three pairs of routers: A–B, B–C, and A–C. The network can be designed to handle this traffic in two ways. 1. No optical add/drop: In the first method, we set up 10 wavelengths on each of the links A–B and B–C connecting the routers at the ends of these links. We observe that the traffic flowing on link A–B is 50 Gb/s (traffic from A–B) 573
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
574 WDM Network Design A B C Router Router Router Router Router Router (a) (b) (c) Figure 10.1 (a) A three-node network. (b) Nodes A–B and B–C are interconnected by WDM links. All wavelengths are dropped and added at node B. (c) Half the wavelengths pass through optically at node B, reducing the number of router ports at node B.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}