IPDVB Working Group M. Stiemerling, Ed. Internet-Draft NEC Expires: April 27, 2006 G. Gardikis Demokritos H. Asgari Thales D. Negru PRiSM T. Ahmed LaBRI October 24, 2005 Problem Statement: Configuration of IP services for IPDVB draft-stiemerling-ipdvb-config-02 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 27, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Future IPDVB networks will require a more powerful configuration Stiemerling, et al. Expires April 27, 2006 [Page 1] Internet-Draft IPDVB Address Configuration October 2005 management of IP addresses and related networking parameters as it is currently provided in such networks. Current discussions within the IPDVB working group have shown that the future usage scenarios and requirements for dynamic configuration management are not yet clearly defined. This memo identifies the problem space for dynamic configuration of IP networking parameters in IPDVB networks. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Network Set-up Scenarios . . . . . . . . . . . . . . . . . . . 4 2.1 Hybrid Bi-directional Set-up - Scenario 1 . . . . . . . . 4 2.2 DVB-based Bi-directional Set-up: Scenario 2 . . . . . . . 5 2.3 DVB-based unidirectional Set-up: Scenario 3 . . . . . . . 6 3. Configuration Scenarios . . . . . . . . . . . . . . . . . . . 7 3.1 Static IP configuration . . . . . . . . . . . . . . . . . 7 3.2 IP configuration via the interaction network . . . . . . . 7 3.3 Complete Bootstrap . . . . . . . . . . . . . . . . . . . . 7 4. Requirements for dynamic IP configuration . . . . . . . . . . 8 5. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8.1 Normative References . . . . . . . . . . . . . . . . . . . 13 8.2 Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 A. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . 16 Stiemerling, et al. Expires April 27, 2006 [Page 2] Internet-Draft IPDVB Address Configuration October 2005 1. Introduction Future IPDVB networks will require a more powerful IP address configuration management as it is currently provided in such networks. The required configuration may depend on the offered services transmitted via DVB. Current discussions within the IPDVB working group have shown that the future usage scenarios and requirements for dynamic configuration of IP addresses and other parameters are not yet clearly defined. Other parameters can be, but are not limited to, multicast addresses, application level gateways (proxies), DNS servers, etc. This memo identifies the problem space, sketches possible future scenarios, and gives an outlook in related areas. The IP address mapping to layer 2 identifier, known as IP address resolution, and the reverse way are out of scope of this memo. This topic is discussed in [5]. The IPDVB working group has defined a new encapsulation scheme to transport IP over DVB (MPEG-2 based) networks, the so-called Unidirectional Lightweight Encapsulation [1]. This protocol assumes that IP addresses have already been assigned to hosts, DVB receivers, and that hosts are already aware of other networking related parameters, such as IP gateway, DNS server, etc. Where today IP addresses are statically assigned to those receivers, future deployments may require more flexible IP address assignment mechanisms such as the ones known from today's LANs, for instance, via DHCP [3] [4]. Assigning IP addresses dynamically opens the path for further IPv4 and IPv6 auto-configuration of DVB receivers. This memo is a problem statement only and is intended to start discussions within the IPDVB working group on how IP addresses and additional related information can be configured dynamically. Comments and discussions should be sent to the IPDVB's mailing list at ipdvb@erg.abdn.ac.uk. The working group charter is available here: http://www.ietf.org/html.charters/ipdvb-charter.html. Section 2 introduces the network configuration for IPDVB networks. Section 3 describes two scenarios in details. Section 4 suggests the requirements to which a possible auto-configuration solution would comply. The document concludes with Section 5 listing similar areas of interest. The terminology used throughout this memo is defined in [2]. Stiemerling, et al. Expires April 27, 2006 [Page 3] Internet-Draft IPDVB Address Configuration October 2005 2. Network Set-up Scenarios The basic assumption for IPDVB networks with respect to IP address configuration is the number of possible receivers (hosts) within a single IP subnetwork. It is assumed that future IPDVB networks can extend to 1*10E5 receivers per subnetwork but can also be limited to 10 or less receivers per subnetwork. This possible number of hosts must be considered when describing scenarios and later the solution. However, the remainder of this section discusses different network scenarios with respect to their topology in the Internet and DVB network. 2.1 Hybrid Bi-directional Set-up - Scenario 1 Figure 1 sketches a hybrid interactive topology, where the downlink is a DVB trunk and the uplink is based on a common (wired or wireless) data networking technology. The (unidirectional) DVB downlink can be either cable, satellite or terrestrial, whereas the (bi-directional) uplink can be, but is not limited to, ISDN, DSL, WLAN/WMAN, or cellular networks based. ,-----. IP link / DVB \ *########>>#########( Network ) # \ / +----*------+ `--.--' | Network | | | Provider +-<->+ v DVB downlink +-----------+ | | | +-----v------+ +-<->--+ DVB | uplink | Receiver | +------------+ Figure 1: Hybrid set-up: scenario 1 The network provider's domain is connected to both, the DVB network and IP bi-directional interaction network. Upon activation of the user terminal, a bi-directional connection is thus established between the receiver and the provider of the interaction network. This communication is mostly based on asymmetric data flow, where data destined to the user are included in the DVB downlink, and the Stiemerling, et al. Expires April 27, 2006 [Page 4] Internet-Draft IPDVB Address Configuration October 2005 uplink is mainly used for requests/acknowledgments and other related signalling. Typical scenarios would include set-ups as: o DVB-S/S.2 with PSTN/ISDN (fixed broadband access) o DVB-T with PSTN/ISDN/xDSL/WLAN/WMAN (fixed terrestrial) o DVB-H with GPRS/3G (mobile use) 2.2 DVB-based Bi-directional Set-up: Scenario 2 Figure 2 shows a scenario where the DVB receiver utilizes DVB-based technologies for both the downlink (DVB-S, DVB-T, DVB-H) and the uplink (DVB-RCS, DVB-RCT). Such a configuration will be used, for instance, on ships while being at sea with a DVB-S only solution available. In this case, DVB-RCS can be used for interaction. In another scenario, DVB-RCT can be used as an uplink in fixed or mobile DVB-T/DVB-H reception, as an alternative to using a cellular network. In all these configurations, all information, including IP addresses, must be transmitted via the DVB links. ,-----. IP link / DVB \ *#######<###>######( Network ) # \ / +----*------+ `--.--' | Network | | | | Provider | DVB uplink ^ v DVB downlink +-----------+ (RCT, RCS) | | (S,T,H) ^ v | | +-----+------+ | DVB | | Receiver | +------------+ Figure 2: Network set-up using DVB links in both directions: scenario 2 Stiemerling, et al. Expires April 27, 2006 [Page 5] Internet-Draft IPDVB Address Configuration October 2005 2.3 DVB-based unidirectional Set-up: Scenario 3 This is a scenario similar to a today's common usage of DVB broadcast, as is shown in Figure 3. The DVB part is an unicast link and all data is broadcasted to all receivers. This configuration is mainly used today for TV broadcasts services (based on MPEG-2) but it can be used to broadcast IP data to the DVB receivers too. In such case, DVB receivers do not have the ability to interact with any external entity for configuration purpose. Address information can be delivered from a network provider to the receivers by a push mechanism only. However, a fine-grained unicast IP address configuration per receiver does not to be very likely in this case, since configuration of broadcast or multicast groups is mostly appropriate. Unicast IP address assignment should anyway be supported for the (scarce but possible) case of operator-initiated unicast push. This could be the scenario when a client issues a request for a block of information (e.g. a movie) to be sent to it via a voice telephone call or an SMS. ,-----. IP link / DVB \ *########>>########( Network ) # \ / +----*------+ `--.--' | Network | | | Provider | v DVB link +-----------+ v | +-----+------+ | DVB | | Receiver | +------------+ Figure 3: DVB-based uni-directional set-up: Scenario 3 Stiemerling, et al. Expires April 27, 2006 [Page 6] Internet-Draft IPDVB Address Configuration October 2005 3. Configuration Scenarios 3.1 Static IP configuration This scenario assumes that the IP address of the user terminal along with its networking (and DVB-related) parameters have been pre- configured. This is an acceptable solution for fixed reception, where the number of users is relatively small. No additional protocol and signalling are required. 3.2 IP configuration via the interaction network The following operation is intended for scenario 1. Figure 1 shows such a configuration example. The DVB receiver will obtain its basic IP address configuration via the non-DVB uplink (most likely via ISDN and PPP, xDSL or 3G/GPRS). The interaction network assigns an IP address, dynamic or static, public or private, to the connected client. This address can represent the terminal as a whole (i.e. there is no need to allocate a second IP address for the DVB receive- only interface). In any case, the scenario of the IP address being configured by the interaction network requires additional configuration to be loaded at the DVB receivers. Possible configurations include: o IP service information, such as DNS server, proxies, etc o multicast configuration and routing information o broadcast configuration (service_id or PID in which the IP data can be found, encapsulation method [ETH] ULE or MPE) o security configuration, e.g., keys, policies, IPsec parameters. 3.3 Complete Bootstrap Scenarios 2 and 3 can require a complete bootstrap of DVB receivers without any pre-configuration available at the IP level. Those DVB receivers may be pre-configured to known a basic DVB configuration, such as PID assignment for a special data stream containing auto- configuration data. Such a receiver would need to retrieve first an IP address and learn about its IP environment (netmask, IP next hop, ...). Figure 2 shows such a scenario where a DVB receiver (and transmitter) is installed aboard a ship and is a gateway between the ship's network and the DVB network. The complete bootstrap scenario includes the one shown in Figure 3 too. Stiemerling, et al. Expires April 27, 2006 [Page 7] Internet-Draft IPDVB Address Configuration October 2005 4. Requirements for dynamic IP configuration Any proposed mechanism for the dynamic configuration of the host's networking parameters should fulfil certain requirements. Specifically, its necessary features should be: 1. Scalability: In contrast to LANs or dial-up environments, in which DHCP or PPP is used, a DVB service can be addressed to thousands of users. The mechanism should be able to process numerous client requests and assign addresses from a large pool. 2. Support for both IPv4 and IPv6: Current DVB receivers support mostly IPv4, because MPE is IPv4-oriented. The forthcoming ULE supports IPv4 and IPv6 in an equal manner, so both protocols must be supported. It might be desirable that a single IP address is assigned to each receiver and not multiple ones (e.g. one for the DVB interface and a second for the interactive interface). 3. Configuration of IP-related parameters: In addition to client IP address, more configuration operations such as gateway address, DNS server address, domain name and IPsec parameters must be performed. 4. Configuration of DVB-related parameters: These parameters such as service_id or PID where the data destined to the user are to be found as well as encapsulation method used (ULE or MPE). Although the association between IP and DVB parameters is actually an address-resolution issue, it would be quite helpful for the receiver to know in advance the TS logical channel containing its data, before having to employ an AR protocol or browse into the INT table (which is anyway impractical for a large number of receivers). Anyway, regardless of the signalling issue, it is the auto-configuration mechanism which should allocate a TS Logical Channel (TSLC) for each user. Depending on the number of associated receivers, this relation could be other than one-to-one (i.e., one TSLC could correspond to multiple users, or a user could retrieve information from multiple TSLCs). 5. Support for authentication mechanisms: The DVB broadcast downlink is 'open' to anyone, but it is rational to assume that bidirectional access is restricted only to authorized receivers. Before sending the IP parameters the dynamic configuration server would follow an authentication process to validate the identity of the client terminal. 6. Handover support: In the case that the receiver moves across neighbouring DVB macrocells (in the terrestrial scenario mostly), the dynamic configuration mechanism should cooperate with the Stiemerling, et al. Expires April 27, 2006 [Page 8] Internet-Draft IPDVB Address Configuration October 2005 handover backplane to ensure that IP connectivity is maintained in the destination cell. The operator can choose either to keep the same IP parameters or allocate new ones to the client terminal upon associating it to the new DVB cell. In the case of SFN implementation, this issue does not exist, as the same multiplex is present in all transmitters, and no handover process actually takes place. Stiemerling, et al. Expires April 27, 2006 [Page 9] Internet-Draft IPDVB Address Configuration October 2005 5. Related Work Configuration of DVB networks, or more generally MPEG-2 based networks, are tackled in several other environments with different prerequisites. The IP over Cable Data Networks (IPDCN) working group is working in this area and is specifying several MIB modules with respect to MPEG2 network configuration. DVB itself has defined several mechanisms to configure receivers, such as system information tables (SI tables), or within MHP. Configuration of IP hosts is the focus of the Network Configuration (NETCONF) working group, Dynamic Host Configuration (DHC) working group, defined in several RFC documents (IPv4 Address Resolution Protocol (ARP), IPv6 neighbour discovery (ND)) etc. Stiemerling, et al. Expires April 27, 2006 [Page 10] Internet-Draft IPDVB Address Configuration October 2005 6. Conclusions This memo is the first attempt to answer the questions on how future IPDVB networks can deal with dynamic IP address configuration. Open questions are: o What are the configuration scenarios? o What exactly should be configured? o How to configure? o Who is in control of the receiver? The operator is in control of the receiver in the case of MHP. Users running a DVB PC adaptor have full control over their receiver and network operators running their routers on DVB networks are likely not to give away control over their equipment. o Is it right to assume that the network provider and DVB network operator are the same entity? For DVB only access networks this might be true, but for future scenarios it is unlikely that the DVB network operator and IP network operator is the same entity. During the first discussions at the 61st IETF some differences between IPDVB and other network configuration techniques have been noted. The NETCONF approach is made for a single router configuration and is not intended to configure thousands of host. IPCDN on the other hand considers 1*10e3 hosts per cable head end to be configured. IPDVB may consider up to 1*10e5 hosts per segment, see Section 2. This must be definitely taken into account when devising a solution. Further discussions amongst the authors have raised the concern about the density of the hosts per subnetwork. Initially, it has been assumed that IPDVB-based subnetworks can consist out of 1*10e5 hosts, because of the broadcast nature of DVB. This raises the scalability issue of any solution. This memo is neither accurate nor complete at this point of time and should trigger the discussions within the IPDVB working group. Feedback about this memo is welcome. Stiemerling, et al. Expires April 27, 2006 [Page 11] Internet-Draft IPDVB Address Configuration October 2005 7. Security Considerations Security considerations are to be done in future revisions of this document. Stiemerling, et al. Expires April 27, 2006 [Page 12] Internet-Draft IPDVB Address Configuration October 2005 8. References 8.1 Normative References [1] Fairhurst, G. and B. Collini-Nocker, "Unidirectional Lightweight Encapsulation (ULE) for transmission of IP datagrams over an MPEG-2 Transport Stream", draft-ietf-ipdvb-ule-06 (work in progress), June 2005. [2] Montpetit, M., "A Framework for transmission of IP datagrams over MPEG-2 Networks", draft-ietf-ipdvb-arch-04 (work in progress), May 2005. 8.2 Informative References [3] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [4] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [5] Fairhurst, G., "Address Resolution for IP datagrams over MPEG-2 networks", draft-fair-ipdvb-ar-04 (work in progress), April 2005. Authors' Addresses Martin Stiemerling (editor) Network Laboratories, NEC Europe Ltd. Kurfuersten-Anlage 36 Heidelberg 69115 Germany Phone: +49 (0) 6221 905 11 13 Email: stiemerling@netlab.nec.de URI: http://www.stiemerling.org/ipdvb Georgios J. Gardikis NCSR "Demokritos", Institute of Informatics and Telecommunications Greece Email: gardikis@iit.demokritos.gr Stiemerling, et al. Expires April 27, 2006 [Page 13] Internet-Draft IPDVB Address Configuration October 2005 Hamid Asgari Thales United Kingdom Email: Hamid.Asgari@thalesgroup.com Daniel Negru PRiSM - Research laboratory in computers sciences France Email: Daniel.Negru@prism.uvsq.fr Toufik Ahmed Laboratoire Bordelais de Recherche en Informatique France Email: tad@labri.fr Stiemerling, et al. Expires April 27, 2006 [Page 14] Internet-Draft IPDVB Address Configuration October 2005 Appendix A. Acknowledgments Parts of this work are a product of the Enthrone project supported in part by the European Commission under its Sixth Framework Programme. It is provided as is and without any express or implied warranties, including, without limitation, the implied warranties of fitness for a particular purpose. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Enthrone project or the European Commission. Stiemerling, et al. Expires April 27, 2006 [Page 15] Internet-Draft IPDVB Address Configuration October 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Stiemerling, et al. Expires April 27, 2006 [Page 16]