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To: Ray Jensen who wrote (1832)	8/5/1998 5:39:00 AM
From: Hiram Walker	Respond to of 12823

Ray, you can increase the fiber capacity without increasing the fiber by economic use of DWDM. There are methods,like HLIT's with distribute 1550 nm analog broadcast from the headend,and 1310 nm narrowcast for internet access. Using HLIT's architecture with 8 DWDM, you split each wavelength off,and send 10 QAM channels down it,each QAM channel going to each node,effectively increasing bandwidth. This is called their invisible hub architecture,and TCOMA is installing it in Dallas right now,and has installed it in 2 places each in Lousiana,and Washington State. This also allows you to provision services closer to the home,like data and internet. I am just trying to point out,conventional wisdom might not be the best way,that DWDM and PON will eventually change the landscape in the Metro Area. TWX is using conventional wisdom by adding fiber,TCI and COX are using HLIT's DWDM to add capacity. TWX is almost exclusively served by Toshiba,and their architecture to me is inferior. Hiram

To: Ray Jensen who wrote (1832)	8/5/1998 6:04:00 AM
From: Hiram Walker	Read Replies (1) \| Respond to of 12823

Ray, a good article about future optical architecture and its limitations,and answers to those limitations. americasnetwork.com This use of the optical signals as a lowest (or highest, depending on your point of view) networking layer also leads to a natural separation of network functions. The optical layer is responsible for provisioning and restoring large circuit connections. This frees the electronic layers of these functions, so the same optical layer can support the current synchronous optical network (Sonet) and an asynchronous transfer mode (ATM) network, as well as an Internet protocol (IP) network directly. These various electronic networks can share a common interface to the optical layer, providing the kind of flexibility needed in transparent optical networks The problems in designing and managing transparent networks are exacerbated when equipment is obtained from multiple vendors. However, the optical layer can be enabled to make critical use of optoelectronic conversion-an opaque architecture that uses regeneration in conjunction with an optical cross-connect. Signals arrive at a network node on 1550 nm WDM systems, which terminate the optical signals, regenerate them, and deliver output at a standard 1300 nm optical interface using transponders. The optical cross-connect then operates on these signals. Multipoint WDM networks will not be deployable unless they are segmented into subsystems that terminate on non-proprietary signal interfaces. In fact, transparent WDM long-haul networks embody no such interfaces. The fundamental transmission-performance knowledge that would be required to specify such interfaces is not within reach. Opaque networks, however, are fundamentally segmented into open interfaces by the 1300 nm cross-office ports on their transponders. Because open interfaces arise at the boundary between each WDM transport system and the optical cross-connects on which its endpoints terminate, multivendor interoperability is achievable. This is HLIT's architecture,1310 NM interfaces,interoperability at the endpoint termination of the 1550 NM signal,which is to narrowcast transponded to each area.The signal is regenerated and passed on to the homes along the 1310 NM wavelength. It is possible to arrange opaque optical cross-connects in various topologies, including mesh-configured networks. When provisioned with suitable spare restoration capacity, opaque mesh networks can provide a particularly robust platform for supporting a diversity of services-circuit switched and packet switched-at various information rates up to and including the line rate itself, with flexible, resource-efficient restoration. Such networks are indifferent to the question whether its constituent wavelengths carry Sonet-, ATM- or IP-based services. Even when considered individually, transmission, performance, cost and network management obstacles associated with transparency make it unlikely that a transparent, reconfigurable, wavelength-selective, cross-connect network could be engineered on anything approaching a national scale. When these considerations are taken collectively, the case seems quite overwhelming. However, transponder-based systems and networks with open interfaces suggest that opaque WDM optical cross-connect-based networks may provide the functional value of their transparent counterparts, and they can be engineered on a national or global scale. This opaque architecture can support multiple electronic networks over the same optical layer while avoiding the difficulties inherent in transparent networks. Opaque network architectures are consistent with current WDM system designs, which generally include the transponders. Viewed in this way, optical networking becomes a near-term opportunity, rather than a distant pipe dream. Hiram

To: Ray Jensen who wrote (1832)	8/5/1998 5:45:00 PM
From: Frank A. Coluccio	Read Replies (1) \| Respond to of 12823

Thanks Ray, Hiram, for your respective views. Ray, a reply from you on such a topic is like a tutorial, and always a welcome treat. Thanks. Hiram, I admire your vendor-independent stance throughout all of this. <grin> I think that the use of additional active elements at the end-points might be useful under certain conditions, but tradeoff analyses would first need to be performed. I see it going either way for marginal situations, and clearly in favor of additional glass for the short- to- intermediate- distance situations, unless we're talking about a business district for commercial use. And in favor of DWDM farther out. But tradeoffs need to be performed, nonetheless. Regards, Frank C.

To: Ray Jensen who wrote (1832)	8/7/1998 10:02:00 AM
From: MikeM54321	Read Replies (1) \| Respond to of 12823

Ray and Frank, Here's how Time Warner's Road Runner is setup. It's from a Fore press release: 1. OC-48(2.5 Gbps) SONET stretches over a 100-mile radius over service area. 2. Fore's Forerunner ATM switches anchor the ATM backbone in the Tampa Data Center. 3. Data Center has 45 network servers with 4 terabytes of data. 4. Network servers are connected via an OC-3(155 Mbps) fiber connection using Fore ATM adapter cards. 5. There are 70 local distribution hubs (27 of them have Fore ATM switches). 6. Each distribution hub serves 20,000 homes. 7. Each 500 home, neighborhood node, is connected to a single port on a Fore switch at the distribution hub. 8. Each home is connected using a 10BaseT-equivalent for up to 10Mbps service. I think(?) this is an example of a Super D design. MikeM(From Florida)