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Network Working Group                                          M. VecchiRequest for Comments: 1686                             Time Warner CableCategory: Informational                                      August 1994IPng Requirements: A Cable Television Industry ViewpointStatus of this Memo   This memo provides information for the Internet community.  This memo   does not specify an Internet standard of any kind.  Distribution of   this memo is unlimited.Abstract   This document was submitted to the IETF IPng area in response toRFC1550.  Publication of this document does not imply acceptance by the   IPng area of any ideas expressed within.  The statements in this   paper are intended as input to the technical discussions within IETF,   and do not represent any endorsement or commitment on the part of the   cable television industry or any of its companies.  Comments should   be submitted to the big-internet@munnari.oz.au mailing list.Table of Contents1. Executive Summary ..........................................22. Cable Television Industry Overview .........................23. Engineering Considerations .................................53.1  Scaling ..................................................53.2  Timescale ................................................53.3  Transition and deployment ................................63.4  Security .................................................73.5  Configuration, administration and operation ..............73.6  Mobile hosts .............................................83.7  Flows and resource reservation ...........................83.8  Policy based routing .....................................103.9  Topological flexibility ..................................103.10 Applicability ............................................103.11 Datagram service .........................................113.12 Accounting ...............................................113.13 Support of communication media ...........................123.14 Robustness and fault tolerance ...........................123.15 Technology pull ..........................................123.16 Action items .............................................134. Security Considerations ....................................135. Conclusions ................................................136. Author's Address ...........................................14Vecchi                                                          [Page 1]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 19941.  Executive Summary   This paper provides comments on topics related to the IPng   requirements and selection criteria from a cable television industry   viewpoint. The perspective taken is to position IPng as a potential   internetworking technology to support the global requirements of the   future integrated broadband networks that the cable industry is   designing and deploying. The paper includes a section describing the   cable television industry and outlining the network architectures to   support  the delivery of entertainment programming and interactive   multimedia digital services, as well as telecommunication and data   communication services.   Cable networks touch on residences, in addition to campuses and   business parks.  Broadband  applications will reach the average,   computer-shy person. The applications will involve a heavy use of   video and audio to provide communication, entertainment and   information-access services. The deployment of these capabilities to   the homes will represent  tens of millions of users.  Impact on the   network and the IPng requirements that are discussed include issues   of scalability, reliability and availability, support for real-time   traffic,  security and privacy, and operations and network   management, among others.2. Cable Television Industry Overview   Cable television networks and the Internet are discovering each   other. It looks like a great match for a number of reasons, the   available bandwidth being the primary driver. Nonetheless, it seems   that the impact of the cable television industry in the deployment of   broadband networks and services is still not fully appreciated. This   section will provide a quick (and simplified) overview of cable   television networks, and explain the trends that are driving future   network architectures and services.   Cable television networks  in the U.S. pass by approximately 90   million homes, and have about 56 million subscribers, of a total of   about 94 million homes (U.S. TV CENSUS figures, 9/30/93). There are   more than 11,000 headends, and the cable TV industry has installed   more than 1,000,000 network-miles. Installation of optical fiber   proceeds at a brisk pace, the fiber plant in the U.S. going from   13,000 miles in 1991 to 23,000 miles in 1992. Construction spending   by the cable industry in 1992 was estimated to be about $2.4 billion,   of which $1.4 billion was for rebuilds and upgrades. Cable industry   revenue from subscriber services in 1992 was estimated to be more   than $21 billion, corresponding to an average subscriber rate of   about $30 per month (source:  Paul Kagan Associates, Inc.). These   figures are based on "conventional" cable television services, andVecchi                                                          [Page 2]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994   are expected to grow as the cable industry moves into new interactive   digital services and telecommunications.   The cable industry's broadband integrated services network   architecture is based on a hierarchical deployment of network   elements interconnected by broadband fiber optics and coaxial cable   links. In a very simplified manner, the following is a view of this   architecture. Starting at the home, a coaxial cable tree-and-branch   plant provides broadband two-way access to the network.  The local   access coaxial cable plant is aggregated at a fiber node, which marks   the point in the network where fiber optics becomes the broadband   transmission medium. Current deployment is for  approximately 500   homes passed by the coaxial cable plant for every fiber node, with   variations (from as low as 100 to as many as 3000) that depend on the   density of homes and the degree of penetration of broadband services.   The multiple links from the fiber nodes reach the headend, which is   where existing cable systems have installed equipment for   origination, reception and distribution of television programming.   The headends are in buildings that can accommodate weather protection   and powering facilities, and hence represent the first natural place   into the network where complex switching, routing and processing   equipment can be conveniently located. Traffic from multiple headends   can be routed over fiber optics to regional hub nodes deeper into the   network, where capital-intensive functions can be shared in an   efficient way.   The cable networks are evolving quite rapidly to become effective   two-way digital broadband networks. Cable networks will continue to   be asymmetric,  and they will continue to deliver analog video. But   digital capabilities are being installed very aggressively and a   significant upstream bandwidth is rapidly being activated. The   deployment of optical fiber deeper into the network is making the   shared coaxial plant more effective in carrying broadband traffic in   both directions. For instance, with fiber nodes down to where only   about 100 to 500 homes are passed by the coaxial drops (down from   tens of thousands of homes passed in the past), an upstream bandwidth   of several MHz represents a considerable capacity. The recent   announcement by Continental Cablevision and PSI to provide Internet   access services is but one example of the many uses that these two-   way broadband capabilities can provide.   The cable networks are also rapidly evolving into regional networks.   The deployment of fiber optic trunking facilities (many based on   SONET) will provide gigabit links that interconnect regional hub   nodes in regional networks spanning multiple cable systems. These   gigabit networks carry digitized video programming, but will also   carry voice (telephone) traffic, and, of course, data traffic. There   are instances in various parts of the country where these regionalVecchi                                                          [Page 3]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994   networks have been in successful trials. And given that compressed   digital video is the way to deliver future video programs (including   interactive video, video on demand, and a whole menu of other   applications like computer supported collaborative work, multiparty   remote games, home shopping, customized advertisement, multimedia   information services, etc.), one can be guaranteed that gigabit   regional networks will be put in place at an accelerated pace.   The cable networks are evolving to provide broadband networking   capabilities in support  of a complete suite of communication   services. The Orlando network being built by Time Warner is an   example of a Full Service Network(TM) that provides video, audio and   data services to the homes. For the trial, ATM is brought to the   homes at DS3 rates, and it is expected to go up to OC-3 rates when   switch interfaces will be available. This trial in Orlando represents   a peek into the way of future cable networks. The Full Service   Network uses a "set-top" box in every home to provide the network   interface. This "set-top" box, in addition to some specialized   modules for video processing, is really a powerful computer in   disguise, with a computational power comparable to high-end desktop   workstations. The conventional analog cable video channels will be   available, but a significant part of the network's RF bandwidth will   be devoted to digital services. There are broadband ATM switches in   the network (as well as 5E-type switches for telephony), and video   servers that include all kinds of movies and information services. An   important point to notice is that the architecture of future cable   networks maps directly to the way networked computing has developed.   General purpose hosts (i.e., the set-top boxes)  are interconnected   through a broadband network to other hosts and to servers.   The deployment of the future broadband information superhighway will   require architectures for both the network infrastructure and the   service support environment that truly integrate the numerous   applications that will be offered to the users. Applications will   cover a very wide range of scenarios.  Entertainment video delivery   will evolve from the current core services of the cable industry to   enhanced offerings like interactive video, near-video-on-demand and   complete video-on-demand functions. Communication services will   evolve from the current telephony and low-speed data to include   interactive multimedia applications, information access services,   distance learning, remote medical diagnostics and evaluations,   computer supported collaborative work,  multiparty remote games,   electronic shopping, etc. In addition to the complexity and diversity   of the applications, the future broadband information infrastructure   will combine a number of different networks that will have to work in   a coherent manner. Not only will the users be connected to different   regional networks, but the sources of information - in the many forms   that they will take - will also belong to different enterprises andVecchi                                                          [Page 4]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994   may be located in remote networks. It is important to realize from   the start that the two most important attributes of the architecture   for the future broadband information superhighway are integration and   interoperability. The Internet community has important  expertise and   technology that could contribute to the definition and development of   these future broadband networks.3. Engineering Considerations   The following comments represent expected requirements of future   cable networks, based on the vision of an integrated broadband   network that will support a complete suite of interactive video,   voice and data services.   3.1  Scaling      The current common wisdom is that IPng should be able to deal with      10 to the 12th nodes. Given that there are of the order of 10 to      the 8th households in the US, we estimate a worldwide  number of      households of about 100 times as many, giving a total of about 10      to the 10th global households. This number represents about 1      percent of the 10 to the 12th nodes, which indicates that there      should be enough space left for business, educational, research,      government, military and other nodes connected to the future      Internet.      One should be cautious, however, not to underestimate the      possibility of multiple addresses that will be used at each node      to specify different devices, processes, services, etc. For      instance, it is very likely that more than one address will  be      used at each household for different devices such as the      entertainment system (i.e., interactive multimedia "next      generation" television(s)), the data system (i.e., the home      personal computer(s)), and other new terminal devices that will      emerge in the future (such as networked games, PDAs, etc.).      Finally, the administration of the address space is of importance.      If there are large blocks of assigned but unused addresses, the      total number of available addresses will be effectively reduced      from the 10 to the 12th nodes that have been originally      considered.   3.2  Timescale      The cable industry is already making significant investments in      plant upgrades, and the current estimates for the commercial      deployment indicate that by the year 1998 tens of millions of      homes will be served by interactive and integrated cable networks      and services. This implies that during 1994 various trials will beVecchi                                                          [Page 5]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      conducted and evaluated, and the choices of technologies and      products will be well under way by the year 1995. That is to say,      critical investment and technological decisions by many of the      cable operators, and their partners, will be made over the next 12      to 24 months.      These time estimates are tentative, of course, and subject to      variations depending on economic, technical and public policy      factors. Nonetheless, the definition of the IPng capabilities and      the availability of implementations should not be delayed beyond      the next year, in order to meet the period during which many of      the early technological choices for the future deployment of cable      networks and services will be made. The full  development and      deployment of IPng will be, of course, a long period that will be      projected beyond the next year. Availability of early      implementations will allow experimentation in trials to validate      IPng choices and to provide early buy-in from the developers of      networking products that will support the planned roll out.      It is my opinion that the effective support for high quality video      and audio streams is one of the critical capabilities that should      be demonstrated by IPng in order to capture the attention of      network operators and information providers of interactive      broadband services (e.g., cable television industry and partners).      The currently accepted view is that IP is a great  networking      environment for the control side of an interactive broadband      system. It is a challenge for IPng to demonstrate that it can be      effective in transporting the broadband video and audio data      streams, in addition to providing the networking support for the      distributed control system.   3.3  Transition and deployment      The transition from the current version to IPng has to consider      two aspects: support for existing applications and availability of      new capabilities. The delivery of digital video and audio programs      requires the capability to do broadcasting and selective      multicasting efficiently. The interactive applications that the      future cable networks will provide will be based on multimedia      information streams that will have real-time constraints. That is      to say, both the end-to-end delays and the jitter associated with      the delivery across the network have to be bound. In addition, the      commercial nature of these large private investments will require      enhanced network capabilities for routing choices, resource      allocation, quality of service controls, security, privacy, etc.      Network management will be an increasingly important issue in the      future. The extent to which the current IP fails to provide the      needed capabilities will provide additional incentive for theVecchi                                                          [Page 6]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      transition to occur, since there will be no choice but to use IPng      in future applications.      It is very important, however, to maintain backwards compatibility      with the current IP. There is the obvious argument that the      installed technological base developed around IP cannot be      neglected under any reasonable evolution scenario. But in      addition, one has to keep in mind that a global Internet will be      composed of many interconnected heterogeneous networks, and that      not all subnetworks, or user communities, will provide the full      suite of interactive multimedia services. Interworking between      IPng and IP will have to continue for a very long time in the      future.   3.4  Security      The security needed in future networks falls into two general      categories: protection of the users and protection of the network      resources. The users of the future global Internet will include      many communities that will likely expect a higher level of      security than is currently available. These users include      business, government, research, military, as well as private      subscribers. The protection of the users' privacy is likely to      become a hot issue as new commercial services are rolled out. The      possibility of illicitly monitoring traffic patterns by looking at      the headers in IPng packets, for instance, could be disturbing to      most users that subscribe to new information and entertainment      services.      The network operators and the information providers will also      expect effective protection of their resources. One would expect      that most of the security will be dealt at higher levels than      IPng, but some issues might have to be considered in defining IPng      as well. One issue relates, again, to the possibility of illicitly      monitoring addresses and traffic patterns by looking at the IPng      packet headers. Another issue of importance will be the capability      of effective network management under the presence of benign or      malicious bugs, especially if both source routing and resource      reservation functionality is made available.   3.5  Configuration, administration and operation      The operations of these future integrated broadband networks will      indeed become more difficult, and not only because the networks      themselves will be larger and more complex, but also because of      the number and diversity of applications running on or through the      networks. It is expected that most of the issues that need to be      addressed for effective operations support systems will belong toVecchi                                                          [Page 7]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      higher layers than IPng, but some aspects should be considered      when defining IPng.      The area where IPng would have most impact would be in the      interrelated issues of resource reservation, source routing and      quality of service control. There will be tension to maintain high      quality of service and low network resource usage simultaneously,      especially if the users can specify preferred routes through the      network. Useful capabilities at the IPng level would enable the      network operator, or the user, to effectively monitor and direct      traffic in order to meet quality and cost parameters. Similarly,      it will be important to dynamically reconfigure the connectivity      among end points or the location of specific processes (e.g., to      support mobile computing terminals), and the design of IPng should      either support, or at least not get in the way of, this      capability. Under normal conditions, one would expect that      resources for the new routing will be established before the old      route is released in order to minimize service interruption. In      cases where reconfiguration is in response to abnormal (i.e.,      failure) conditions, then one would expect longer interruptions in      the service, or even loss of service.      The need to support heterogeneous multiple administrative domains      will also have important implications on the available addressing      schemes that IPng should support. It will be both a technical and      a business issue to have effective means to address nodes,      processes and users, as well as choosing schemes based on fair and      open processes for allocation and administration of the address      space.   3.6  Mobile hosts      The proliferation of personal and mobile communication services is      a well established trend by now. Similarly, mobile computing      devices are being introduced to the market at an accelerated pace.      It would not be wise to disregard the issue of host mobility when      evaluating proposals for IPng.  Mobility will have impact on      network addressing and routing, adaptive resource reservation,      security and privacy, among other issues.   3.7  Flows and resource reservation      The largest fraction of the future broadband traffic will be due      to real-time voice and video streams. It will be necessary to      provide performance bounds for bandwidth, jitter, latency and loss      parameters, as well as synchronization between media streams      related by an application in a given session. In addition, there      will be alternative network providers that will compete for theVecchi                                                          [Page 8]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      users and that will provide connectivity to a given choice of many      available service providers. There is no question that IPng, if it      aims to be a general protocol useful for interactive multimedia      applications, will need to support some form of resource      reservation or flows.      Two aspects are worth mentioning. First, the quality of service      parameters are not known ahead of time, and hence the network will      have to include flexible capabilities for defining these      parameters. For instance, MPEG-II packetized video might have to      be described differently than G.721 PCM packetized voice, although      both data streams represent real-time traffic channels. In some      cases, it might be appropriate to provide soft guarantees in the      quality parameters, whereas in other cases hard guarantees might      be required. The tradeoff between cost and quality could be an      important capability of future IPng-based networks, but much work      needs to be advanced on this.      A second important issue related to resource reservations is the      need to deal with broken or lost end-to-end state information. In      traditional circuit-switched networks, a considerable effort is      expended by the intelligence of the switching system to detect and      recover resources that have been lost due to misallocation. Future      IPng networks will provide resource reservation capabilities by      distributing the state information of a given session in several      nodes of the network. A significant effort will be needed to find      effective methods to maintain consistency and recover from errors      in such a distributed environment. For example, keep-alive      messages to each node where a queuing policy change has been made      to establish the flow could be a strategy to make sure that      network resources do not remain stuck in some corrupted session      state. One should be careful, however, to assume that complex      distributed algorithms can be made robust by using time-outs. This      is a problem that might require innovation beyond the reuse of      existing solutions.      It should be noted that some aspects of the requirements for      recoverability are less stringent in this networking environment      than in traditional distributed data processing systems. In most      cases it is not needed (or even desirable) to recover the exact      session state after failures, but only to guarantee that the      system returns to some safe state. The goal would be to guarantee      that no network resource is reserved that has not been correctly      assigned to a valid session. The more stringent requirement of      returning to old session state is not meaningful since the value      of a session disappears, in most cases, as time progresses. One      should keep in mind, however, that administrative and management      state, such as usage measurement, is subject to the sameVecchi                                                          [Page 9]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      conventional requirements of recoverability that database systems      currently offer.   3.8  Policy based routing      In future broadband networks, there will be multiple network      operators and information providers competing for customers and      network traffic.  An important capability of IPng will be to      specify, at the source, the specific network for the traffic to      follow. The users will be able to select specific networks that      provide performance, feature or cost advantages. From the user's      perspective, source routing is a feature that would enable a wider      selection of network access options, enhancing their ability to      obtain features, performance or cost advantages. From the network      operator and service provider perspective, source routing would      enable the offering of targeted bundled services that will cater      to specific users and achieve some degree of customer lock-in. The      information providers will be able to optimize the placement and      distribution of their servers, based on either point-to-point      streams or on multicasting to selected subgroups. The ability of      IPng to dynamically specify the network routing would be an      attractive feature that will facilitate the flexible offering of      network services.   3.9  Topological flexibility      It is hard to predict what the topology of the future Internet      will be. The current model developed in response to a specific set      of technological drivers, as well as an open administrative      process reflecting the non-commercial nature of the sector. The      future Internet will continue to integrate multiple administrative      domains that will be deployed by a variety of network operators.      It is likely that there will be more "gateway" nodes (at the      headends or even at the fiber nodes, for instance) as local and      regional broadband networks will provide connectivity for their      users to the global Internet.   3.10 Applicability      The future broadband networks that will be deployed, by both the      cable industry and other companies, will integrate a diversity of      applications. The strategies of the cable industry are to reach      the homes, as well as schools, business, government and other      campuses. The applications will focus on entertainment, remote      education, telecommuting, medical, community services, news      delivery and the whole spectrum of future information networking      services. The traffic carried by the broadband networks will be      dominated by real-time video and audio streams, even though thereVecchi                                                         [Page 10]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      will also be an important component of traffic associated with      non-time-critical services such messaging, file transfers, remote      computing, etc. The value of IPng will be measured as a general      internetworking technology for all these classes of applications.      The future market for IPng could be much wider and larger than the      current market for IP, provided that the capabilities to support      these diverse interactive multimedia applications are available.      It is difficult to predict how pervasive the use of IPng and its      related technologies might be in future broadband networks. There      will be extensive deployment of distributed computing      capabilities, both for the user applications and for the network      management and operation support systems that will be required.      This is the area where IPng could find a firm stronghold,      especially as it can leverage on the extensive IP technology      available. The extension of IPng to support video and audio real-      time applications, with the required performance, quality and cost      to be competitive, remains a question to be answered.   3.11 Datagram service      The "best-effort", hop-by-hop paradigm of the existing IP service      will have to be reexamined if IPng is to provide capabilities for      resource reservation or flows. The datagram paradigm could still      be the basic service provided by IPng for many applications, but      careful thought should be given to the need to support real-time      traffic with (soft and/or hard) quality of service requirements.   3.12 Accounting      The ability to do accounting should be an important consideration      in the selection of IPng. The future broadband networks will be      commercially motivated, and measurement of resource usage by the      various users will be required. The actual billing may or may not      be based on session-by-session usage, and accounting will have      many other useful purposes besides billing. The efficient      operation of networks depends on maintaining availability and      performance goals, including both on-line actions and long term      planning and design. Accounting information will be important on      both scores. On the other hand, the choice of providing accounting      capabilities at the IPng level should be examined with a general      criterion to introduce as little overhead as possible. Since      fields for "to", "from" and time stamp will be available for any      IPng choice, careful examination of what other parameters in IPng      could be useful to both accounting and other network functions so      as to keep IPng as lean as possible.Vecchi                                                         [Page 11]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994   3.13 Support of communication media      The generality of IP should be carried over to IPng. It would not      be an advantage to design a general internetworking technology      that cannot be supported over as wide a class of communications      media as possible. It is reasonable to expect that IPng will start      with support over a few select transport technologies, and rely on      the backwards compatibility with IP to work through a transition      period. Ultimately, however, one would expect IPng to be carried      over any available communications medium.   3.14 Robustness and fault tolerance      Service availability, end-to-end and at expected performance      levels, is the true measure of robustness and fault-tolerance. In      this sense, IPng is but one piece of a complex puzzle. There are,      however, some vulnerability aspects of IPng that could decrease      robustness. One general class of bugs will be associated with the      change itself, regardless of any possible enhancement in      capabilities. The design, implementation and testing process will      have to be managed very carefully. Networks and distributed      systems are tricky. There are plenty of horror stories from the      Internet community itself to make us cautious, not to mention the      brief but dramatic outages over the last couple of years      associated with relatively small software bugs in the control      networks (i.e., CCS/SS7 signaling) of the telephone industry, both      local and long distance.      A second general class of bugs will be associated with the      implementation of new capabilities. IPng will likely support a      whole set of new functions, such as larger (multiple?) address      space(s), source routing and flows, just to mention a few.      Providing these new capabilities will require in most cases      designing new distributed algorithms and testing implementation      parameters very carefully. In addition, the future Internet will      be even larger, have more diverse applications and have higher      bandwidth. These are all factors that could have a multiplying      effect on bugs that in the current network might be easily      contained. The designers and implementers of IPng should be      careful. It will be very important to provide the best possible      transition process from IP to IPng. The need to maintain      robustness and fault-tolerance is paramount.   3.15 Technology pull      The strongest "technology pull" factors that will influence the      Internet are the same that are dictating the accelerated pace of      the cable, telephone and computer networking world. The followingVecchi                                                         [Page 12]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994      is a partial list: higher network bandwidth, more powerful CPUs,      larger and faster (static and dynamic) memory, improved signal      processing and compression methods, advanced distributed computing      technologies, open and extensible network operating systems, large      distributed database management and directory systems, high      performance and high capacity real-time servers, friendly      graphical user interfaces, efficient application development      environments. These technology developments, coupled with the      current aggressive business strategies in our industry and      favorable public policies, are powerful forces that will clearly      have an impact on the evolution and acceptance of IPng. The      current deployment strategies of the cable industry and their      partners do not rely on the existence of commercial IPng      capabilities, but the availability of new effective networking      technology could become a unifying force to facilitate the      interworking of networks and services.   3.16 Action items      We have no suggestions at this time for changes to the      directorate, working groups or others to support the concerns or      gather more information needed for a decision. We remain available      to provide input to the IPng process.4.  Security Considerations   No comments on general security issues are provided, beyond the   considerations presented in the previous subsection 3.4 on network   security.5.  Conclusions   The potential for IPng to provide a universal internetworking   solution is a very attractive possibility, but there are many hurdles   to be overcome. The general acceptance of IPng to support future   broadband services will depend on more than the IPng itself. There is   need for IPng to be backed by the whole suite of Internet technology   that will support the future networks and applications. These   technologies must include the adequate support for commercial   operation of a global Internet that will be built, financed and   administered by many different private and public organizations.   The Internet community has taken pride in following a nimble and   efficient path in the development and deployment of network   technology. And the Internet has been very successful up to now. The   challenge is to show that the Internet model can be a preferred   technical solution for the future. Broadband networks and services   will become widely available in a relatively short future, and thisVecchi                                                         [Page 13]

RFC 1686     A Cable Television Industry Viewpoint on IPng   August 1994   puts the Internet community in a fast track race. The current process   to define IPng can be seen as a test of the ability of the Internet   to evolve from its initial development - very successful but also   protected and limited in scope  - to a general technology for the   support of a commercially viable broadband marketplace.  If the   Internet model is to become the preferred general solution for   broadband networking,  the current IPng process seems to be a   critical starting point.6.  Author's Address   Mario P. Vecchi   Time Warner Cable,   160 Inverness Drive West   Englewood, CO 80112   Phone: (303) 799-5540   Fax: (303) 799-5651   EMail: mpvecchi@twcable.comVecchi                                                         [Page 14]