Editor's note: These minutes have not been edited. IPACD BOF Meeting Minutes: The IP Applications Over Cable Data Network (IPACD) BOF session at the Montreal IETF was held on Monday, June 24th from 3:30 PM to 5:30 PM under the INT SWG. The IPACD BOF was called and chaired by Masuma Ahmed in order to determine interest and level of participation to form a working group to define network interfaces for supporting IP applications over Cable Television (CATV) data network service. The primary agenda of the BOF was to discuss the structure and charter of the proposed working group. The agenda also included formal presentations from two cable industry leaders, Mario Vecchi from Excalibur Group of Time Warner Cable (TWC) and Dave Fellows from Continental Cablevision who described their experiences and requirements extracted from deploying Internet services over CATV data network. The IPACD BOF session was very well attended with close to 200 attendees. The attendees represented a broad segment of industry groups with representations primarily from cable modem companies, Internet service providers (ISPs), CATV and telecommunications operators, and data communications and networking companies. About two third of the attendees expressed interest in forming an IPACD working group to work on the proposed work items put forth at the meeting. The preliminary work items identified for the proposed WG include: - an informational RFC on CATV data network architecture framework and terminology - standards-track RFCs on IP over CATV data network and MIBs - liaison with other IETF WGs to work on some of the CATV data network and service specifications The BOF session minutes are described in detail below. 1. The meeting was started with an overview presentation by Masuma Ahmed from Terayon Corporation who described the purpose of the IPACD BOF and the scope and deliverables of the proposed IPACD working group (WG). She also provided a brief introduction to CATV network and services and the delineation between the proposed IETF WG and the IEEE 802.14. The following summarizes the topics covered in the presentation: - The WG Goals - specify: * IP service feature & application/implementation of LIS & ARP over CATV data network * DHCP and its application of IP address allocation over CATV data network * Element management architecture & MIBs for CATV data service * RF spectrum management architecture & MIB for CATV data network - WG Deliverables: * Three-standard track RFCs relating to: Þ IP over CATV data network service Þ RF spectrum management architecture & MIB Þ CATV data network management architecture & MIB * Proposed standards by 7/97 - When concern was raised about potential overlap between IETF activities and IEEE 802.14, it was pointed out that IEEE 802.14 deals with PHY and MAC only. It was recognized that the proposed IETF WG would be much broader in scope and would provide specifications for the end-to-end CATV data networking and management issues. - Overview of CATV service characteristics: * Currently analog video services but potential support for IP services * Use of frequency division multiplexing (FDM) and 6 MHz channelization plan (8 MHz in Europe) * Analog video broadcast, NTSC 1-way * Digital video broadcast, 30 Mbps/6MHz * Two-way data and multimedia services: Up to 30 Mbps in the downstream direction (delivered to the customer home from the cable headend), and up to 10 Mbps in the upstream direction (from the customers home to the cable headend), IP-based data services (Internet access) - Internet draft submission by Masuma Ahmed and Mario Vecchi titled draft-ahmed-csmimib-mib-00.txt provided more information on CATV network architectures. - Masuma explained the main components of a CATV network: SONET ring interconnects between major headends, fiber from the headend to fiber nodes, and then coaxial cable distribution from the fiber node to subscribersâ homes over coaxial amplifier cascades. - Frequency allocation for CATV networks is as follows: Forward 54-750 MHz, Reverse 5 - 42 MHz, 6 MHz forward channels - Masuma explained the various Internet service interface points (I/Fs) for a CATV Data Network: A complete diagram illustrating all interface points (I/Fs), management system, CDMTS, etc. can be obtained from Masuma Ahmed. - The following example diagrams were briefly explained: * Schematic of CATV Data Protocol Architecture: for both home & headend equipment * Schematic of cable data modem termination system (CDMTS) and cable data modem (CDM) Protocol Architectures including the control architecture for auto-ranging, initialization, packet filtering, registration, etc. 2. The second presentation was made by Mario Vecchi from Excalibur Group of Time Warner Cable who described the Time Warner Cableâs data service experiences and requirements: * CATV Data Service Properties: Þ Connectionless access: LAN-like, no dial-up Þ High speed Þ Standard data communications network * Excalibur Structure: Þ Networking: Access network (HFC & cable modem), metropolitan (SONET, ATM, FDDI); Global access: Internet, etc. Þ Client software Þ Server software * Excalibur Global View: Þ Inter-networked autonomous system Þ Allow connectivity to outside systems, e.g., PSTN * Typical TWC CATV Plant Architecture: Þ Distribution Hub with typically 20,000 homes passed. From there signals transmitted to fiber nodes servicing 500 homes each. Distribution Hubs interconnected via a private backbone network to a centralized headend. * Excalibur Reference Architecture: Þ 10 Base-T from home PC to cable modem. Cable modem is connected to the coaxial cable plant. Þ From coax to fiber node & to a distribution hub (20k homes) which contains the required signal conversion systems. Þ OC3/DS3, FDDI interfaces to outside data networks Þ IP router/switch to provide Internet access When issues were raised about the proposed IETF WG work items, Mario responded that the IETF needs to address issues dealing with RF spectrum management; CATV network performance parameters and types of MIB variables needed; automated modem activation (e.g., the user or the network should not have to initiate any download of information into the cable modem to make it active, i.e., a modem would come service- ready); and IP address assignment and its impact on activities such as cable data modem self-activation. - Mario provided further clarifications on bandwidth management by explaining that there were two basic aspects to bandwidth management: (i) spectrum management to allocate RF bandwidth to different services, and (ii) traffic management per user or per application basis. - It was suggested that, as a first step, the IETF WG needs to define a set of common CATV terminology and architectural framework to ensure that standards proposed can be applied consistently across all CATV networks. 3. The next agenda item was presented by Dave Fellows from Continental Cablevision who described Continental Cablevisionâs experience in delivering high-speed CATV Data Services. Following are the main points covered: * Broadband service features: Þ Delivery of high-speed data Þ $1,500 set top box (STB) ¼ Home PC Þ Two generic markets: Internet access & work at home Þ Many niche markets * Architecture Toward Home Þ Fiber as deep as market will support * Regional Networks Þ Headends linked by high-speed networks, i.e. SONET, with links to content and services, e.g., the Internet Þ Headends typically ATM-linked in Continentalâs case * Business model: Þ Video business = carrying content to TV Þ Data business = carrying content to the PC Þ Carrying content Õ controlling content. Continental has no interest in controlling content * Continental Service: Þ Project Agora - Boston College network * 6000 students, 2500 faculty, 20 cable commuters Þ Exeter, New Hampshire medical network Þ Eastern Massachusetts network * 200 homes served with BBN Planet Þ Past network experience offering services with PSI & Compuserve * Cambridge public library has been on-line for 2+ years When issues were raised about what would the cable operators do if the IETF WG develops standards that are different from what is supported in cable modem systems that Continental and other operators have deployed today, Dave responded that Continental is prepared to support and deploy any new, standard protocols with pre-existing technology. The current technology will eventually be phased out and is referred to as "boat anchors" at this point in the game. - Dave commented that there may soon be 3 levels of standards activities: * MCNS - equivalent to Bellcore technical specifications * IEEE 802.14 dealing with PHY and MAC standardization * IETF - which can provide broad data and network management expertise. 4. Paul Mockapartis from @Home highlighted the following items: * It is important that cable modems be made IP friendly * There are no cable standards today and vendors frantically playing standard games and IETF has the opportunity to improve the situation. * CATV data network needs to allow: i) Bridge & Router architecture ii) ATM as well as ATM-free networks * Standards are needed for: i) Encryption at the link layer and end-to-end protocol. Not necessary to invent things but work with the other IETF WGs for some of the specifications. ii) Multicast support iii) QOS: priority/fairness iv) For tele-work applications: Filtering and encapsulation IETF is the body that can tell other IETF WGs about the CATV data requirements to support the features listed above. The following CATV data network features were highlighted to distinguish them from current, traditional Ethernet implementations: a) Asymmetric architecture b) Higher bandwidth than 10 Mbps c) Requires different mechanisms to support ARP and other data networking features. 4. A brief overview of the DAVIC was then presented by Harri Hakulinen from Nokia Research Center: * DAVIC is a group of 280 companies which published DAVIC 1.0 specifications for Video On Demand (VOD) and other applications * DAVIC 1.1 (July) will address open system specifications containing a cable modem specification with Îcable modemâ being defined as an IP forwarder and 30 Mbps ATM or MPEG downstream and 1.5 or 3 Mbps ATM upstream specifications. When issues were raised about DAVIC implementation experience and IP forwarder definition, it was indicated that there is currently no implementation experience available and the IP forwarder is not that well defined and could be a very simple IP router. The final agenda of the session focused on discussion of the WG work items and the WG structure. As mentioned earlier, overwhelming majority of the attendees expressed interest in forming a WG and to work on the specifications that will facilitate IP support over the CATV data networks and management of these data networks. Note: Esteban Sandino from Rogers Cable helped me in preparing the IPACD BOF meeting minutes. I recorded the following additional items during the last minutes of the session wrap-up by Frank Kastenholz: It was raised that a Subscriber Interface should be defined by the IETF effort. If was observed that the residential access is a new type of subnetwork and that the effort should concentrate on answering the normal IP related questions of 1) how we make IP work well over this new subnetwork, and 2) how we manage IP over this new subnetwork. The meeting ran out of time without being able to discuss these points. Regards, Mark Masuma Ahmed IPACD BOF Chair