6LoWPAN Working Group D. Kaspar Internet-Draft Simula Research Laboratory Expires: August 25, 2008 E. Kim ETRI C. Gomez Technical University of Catalonia (UPC) C. Bormann Universitaet Bremen TZI February 22, 2008 Problem Statement and Requirements for 6LoWPAN Mesh Routing draft-dokaspar-6lowpan-routreq-04 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 August 25, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). Kaspar, et al. Expires August 25, 2008 [Page 1] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 Abstract This document provides the problem statement for 6LoWPAN mesh routing. It also defines the requirements for 6LoWPAN mesh routing considering the low-power characteristics of the network and its devices. Table of Contents 1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 2. Design Space . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Scenario Considerations . . . . . . . . . . . . . . . . . . . 8 4. 6LoWPAN Routing Requirements . . . . . . . . . . . . . . . . . 11 4.1. Routing Requirements depending on the 6LoWPAN Device Types/Roles . . . . . . . . . . . . . . . . . . . . . . . 11 4.2. Routing Requirements depending on Types of 6LoWPAN Applications . . . . . . . . . . . . . . . . . . . . . . . 13 4.3. Mesh-under Specific Requirements . . . . . . . . . . . . . 15 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. Normative References . . . . . . . . . . . . . . . . . . . 18 7.2. Informative References . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Intellectual Property and Copyright Statements . . . . . . . . . . 20 Kaspar, et al. Expires August 25, 2008 [Page 2] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 1. Problem Statement Low-power wireless personal area networks (LoWPANs) are formed by devices complying to the IEEE 802.15.4 standard [7][8]. LoWPAN devices are distinguished by their low bandwidth, short range, scarce memory capacity, limited processing capability and other attributes of inexpensive hardware. In this document, the characteristics of nodes participating in LoWPANs are assumed to be those described in [5]. IEEE 802.15.4 networks support star and mesh topologies and consist of two different device types: reduced-function devices (RFDs) and full-function devices (FFDs). RFDs have the most limited capabilities and are intended to perform only simple and basic tasks. RFDs may only associate with a single FFD at a time, but FFDs may form arbitrary topologies and accomplish more advanced functions, such as multi-hop routing. However, neither the IEEE 802.15.4 standard nor the 6LoWPAN format specification ("IPv6 over IEEE 802.15.4" [6]) specify how mesh topologies could be obtained and maintained. Routing in mesh networks has been the subject of much research. Also in the IETF, a number of experimental protocols have been developed in the Mobile Ad-hoc Networks (MANET) working group, such as AODV [2], OLSR [3], or DYMO [11]. However, these existing routing protocols may not be satisfying for mesh routing in a LoWPAN domain, for the following reasons: o 6LoWPAN nodes have special types and roles, such as primary battery-operated RFDs, battery-operated and mains-powered FFDs, possibly RFDs and FFDs of various capability levels, mains-powered and high-performance gateways, data aggregators, etc. 6LoWPAN routing protocols should support multiple device types and roles. o Handling sleeping nodes is very critical in 6LoWPANs, more than in traditional ad-hoc networks. 6LoWPAN nodes might stay in sleep- mode for most of the time. Time synchronization is important for efficient forwarding of packets. o A possibly simpler routing problem; 6LoWPANs might be either transit-networks or stub-networks. However, we can focus on stub networks first as many practical 6LoWPANs are configured with stub networks at this moment. We can simplify networks by an assumption of no transit networks. o A possibly harder routing problem; routing in 6LoWPANs requires to consider power-optimization, harsh environment, data-aware routing, etc. These are not easy requirements to satisfy Kaspar, et al. Expires August 25, 2008 [Page 3] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 together. This creates new challenges on obtaining robust and reliable mesh routing within LoWPANs. Using the 6LoWPAN header format, there are two layers routing protocols can be defined at, commonly referred to as "mesh-under" and "route-over". The mesh-under approach supports routing under the IP link and is directly based on the link-layer IEEE 802.15.4 standard, therefore using (64-bit or 16-bit short) MAC addresses. On the other hand, the route-over approach relies on IP routing and therefore supports routing over possibly various types of interconnected links (see also Figure 1). Most statements in this draft apply to both the mesh-under and route- over cases. The 6LoWPAN problem statement document ("6LoWPAN Problems and Goals" [5]) briefly mentions four requirements on routing protocols; (a) low overhead on data packets (b) low routing overhead (c) minimal memory and computation requirements (d) support for sleeping nodes considering battery saving These four high-level requirements only describe the need for low overhead and power saving. But, based on the fundamental features of LoWPAN, more detailed routing requirements are presented in this document, which can lead to further analysis and protocol design. In summary, the main problems of mesh routing in LoWPANs are: 1. Existing routing solutions do not operate in 6LoWPAN's adaptation layer (and do not support the addressing scheme defined by IEEE 802.15.4). If a routing protocol for 6LoWPAN is designed to run in the IP layer, it should be adapted to meet the 6LoWPAN- specific requirements. It must be evaluated which layer is most suitable for 6LoWPAN routing. 2. The precise 6LoWPAN routing requirements must be defined. 3. It needs to be clarified how existing routing solutions can be adapted to meet the low-power requirements presented in Section 4. Kaspar, et al. Expires August 25, 2008 [Page 4] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 Considering the problems above, this draft addresses mesh routing requirements for 6LoWPANs for both mesh-under and route-over routing protocol design. Application-specific features affect the design of 6lowpan routing requirements and the corresponding solutions. However, various applications can be profiled by similar technical characteristics. This document states the requirements to consider the general features of all categories of 6LoWPAN applications. However, one single routing solution may not be the best one for all 6LoWPAN applications. Kaspar, et al. Expires August 25, 2008 [Page 5] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 2. Design Space Apart from a wide variety of routing algorithms possible for 6LoWPAN, the question remains as to whether routing should be performed mesh- under (in the adaptation layer defined by the 6lowpan format document [6]), or in the IP-layer using a route-over approach. The most significant consequence of mesh-under routing is that routing would be directly based on the IEEE 802.15.4 standard, therefore using (64- bit or 16-bit shortened) MAC addresses instead of IP addresses, and a LoWPAN would be seen as a single IP link. In case a route-over mechanism is to be applied to a LoWPAN it must also support 6LoWPAN's unique properties using global IPv6 addressing. Additionally, because of the low-performance characteristics of LoWPANs, a light-weight routing protocol must be produced that meets the design goals and requirements presented in this document. Figure 1 shows the place of 6LoWPAN mesh routing in the entire network stack; +-----------------------------+ +-----------------------------+ | Application Layer | | Application Layer | +-----------------------------+ +-----------------------------+ | Transport Layer (TCP/UDP) | | Transport Layer (TCP/UDP) | +-----------------------------+ +-----------------------------+ | Network Layer (IPv6) | | Network +---------+ | +-----------------------------+ | Layer | Routing | | | 6LoWPAN +---------+ | | (IPv6) +---------+ | | Adaptation | Routing | | +-----------------------------+ | Layer +---------+ | | 6LoWPAN Adaptation Layer | +-----------------------------+ +-----------------------------+ | IEEE 802.15.4 (MAC) | | IEEE 802.15.4 (MAC) | +-----------------------------+ +-----------------------------+ | IEEE 802.15.4 (PHY) | | IEEE 802.15.4 (PHY) | +-----------------------------+ +-----------------------------+ Figure 1: Mesh-under (left) and route-over routing (right) In order to avoid packet fragmentation and the overhead for reassembly, routing packets should fit into a single IEEE 802.15.4 physical frame and application data should not be expanded to an extent that they no longer fit. If a mesh-under routing protocol is built for operation in 6LoWPAN's adaptation layer, routing control packets are placed after the 6LoWPAN Dispatch. Multiple routing protocols can be supported by the usage of different Dispatch bit sequences. When a route-over protocol is built in the IPv6 layer, the Dispatch value can be chosen Kaspar, et al. Expires August 25, 2008 [Page 6] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 as one of the Dispatch patterns for 6LoWPAN compressed or uncompressed IPv6, followed by the IPv6 header. Kaspar, et al. Expires August 25, 2008 [Page 7] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 3. Scenario Considerations IP-based low-power WPAN technology is still in its early stage of development, but the range of conceivable usage scenarios is tremendous. The numerous possible applications of sensor networks make it obvious that mesh topologies will be prevalent in LoWPAN environments and routing will be a necessity for expedient communication. Research efforts in the area of sensor networking have put forth a large variety of multi-hop routing algorithms [9]. Most related work focuses on optimizing routing for specific application scenarios, which can largely be categorized into the following models of communication: o Flooding (in very small networks) o Data-aware routing (dissemination vs. gathering) o Event-driven vs. query-based routing o Geographic routing o Probabilistic routing o Hierarchical routing Depending on the topology of a LoWPAN and the application(s) running over it, these different types of routing may be used. However, this draft abstracts from application-specific communication and describes general routing requirements valid for any type of routing in LoWPANs. The following parameters can be used to describe specific scenarios in which the candidate routing protocols could be evaluated. a. Network Properties: * Device Number, Density and Network Diameter: These parameters usually affect the routing state directly (e.g. the number of entries in a routing table or neighbor list). Especially in large and dense networks, policies must be applied for discarding "low-quality" and stale routing entries in order to prevent memory overflow. * Connectivity: Due to external factors or programmed disconnections, a LoWPAN can be in several states of connectivity; anything in the range from "always connected" to "rarely connected". This poses great challenges to the dynamic discovery of routes Kaspar, et al. Expires August 25, 2008 [Page 8] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 across a LoWPAN. * Dynamicity (incl. mobility): Location changes can be induced by unpredictable external factors or by controlled motion, which may in turn cause route changes. Also, nodes may dynamically be introduced into a LoWPAN and removed from it later. The routing state and the volume of control messages is heavily dependent on the number of moving nodes in a LoWPAN and their speed. * Deployment: In a LoWPAN, it is possible for nodes to be scattered randomly or to be deployed in an organized manner. The deployment can occur at once, or as an iterative process, which may also affect the routing state. * Spacial Distribution of Nodes and Gateways: Network connectivity depends on node spatial distribution besides other factors like device number, density and transmission range. For instance, nodes can be placed on a grid, or can be randomly placed in an area (bidimensional Poisson distribution), etc. In addition, if the LoWPAN is connected to other networks through infrastructure nodes called gateways, the number and spatial distribution of gateways affects network congestion and available bandwidth, among others. * Traffic Patterns, Topology and Applications: The design of a LoWPAN and the requirements on its application have a big impact on the most efficient routing type to be used. For different traffic patterns (point-to-point, multipoint-to-point, point-to-multipoint) and network architectures, various routing mechanisms have been introduced, such as data-aware, event-driven, address-centric, and geographic routing. * Quality of Service (QoS): For mission-critical applications, support of QoS is mandatory in resource-constrained LoWPANs and cannot be achieved without a certain degree of control message overhead. * Security: LoWPANs may carry sensitive information and require a high level of security support where the availability, integrity, and confidentiality of data are primordial. Secured messages cause overhead and affect the power consumption of LoWPAN routing protocols. Kaspar, et al. Expires August 25, 2008 [Page 9] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 b. Node Parameters: * Processing Speed and Memory Size: These basic parameters define the maximum size of the routing state. LoWPAN nodes may have different performance characteristics beyond the common RFD/FFD distinction. * Power Consumption and Power Source: The number and topology of battery- and mains-powered nodes in a LoWPAN affect routing protocols in their selection of optimal paths for network lifetime maximization. * Transmission Range: This parameter affects routing. For example, a high transmission range may cause a dense network, which in turn results in more direct neighbors of a node, higher connectivity and a larger routing state. * Traffic Pattern: This parameter affects routing since high- loaded nodes (either because they are the source of packets to be transmitted or due to forwarding) may incur a greater contribution to delivery delays than low-loaded nodes. This applies to both data packets and routing control messages themselves. Kaspar, et al. Expires August 25, 2008 [Page 10] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 4. 6LoWPAN Routing Requirements This section defines a list of requirements for 6LoWPAN routing. The most important design property unique to low-power networks is that 6LoWPANs support multiple device types and roles, for example: o primary battery-operated RFDs o battery-operated and mains-powered FFDs o possibly various levels of RFDs and FFDs o mains-powered, high-performance gateway(s) o data aggregators, etc. Due to these unique device types and roles 6LoWPANs need to consider the following two primary features: o Power conservation: some devices are mains-powered, but most are battery-operated and need to last several months to a few years with a single AA battery. Many devices are mains-powered most of the time, but still need to function for possible extended periods from batteries (e.g. before building power is switched on for the first time). o Low performance: tiny devices, memory sizes, processors, low bandwidth, high loss rates, etc. These fundamental features of LoWPANs affect the design of routing solutions, so that existing routing specifications should be simplified and modified to the smallest extent possible, in order to fit the low-power requirements of LoWPANs, meeting the following requirements: 4.1. Routing Requirements depending on the 6LoWPAN Device Types/Roles The general objectives listed in this subsection should be followed by 6LoWPAN routing protocols. The importance of each requirement is dependent on what device type the protocol is running on and what the role of the device is. R01: 6LoWPAN routing protocols SHOULD be simple and of low computational complexity. A LoWPAN routing protocol should be designed to minimize the required memory size, computational and algorithmical complexity. A routing protocol of low complexity helps to achieve the goal of Kaspar, et al. Expires August 25, 2008 [Page 11] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 reducing power consumption, improves robustness, is more easy to analyze, and is implicitly less prone to security attacks. R02: 6LoWPAN routing protocols SHOULD have a low routing state. Operation with low routing state (such as routing tables and neighbor lists) SHOULD be maintained. For example, devices may have only 32 forwarding entries available. A LoWPAN routing protocol solution should consider the limited memory size (typically starting at 4K bytes, in which it is hard to store neighbor state of 100s of nodes) and computation capabilities of participating devices; due to these hardware restrictions, code length should be considered to fit within a small memory size. R03: 6LoWPAN routing protocols SHOULD cause minimal power consumption, both in the efficient use of control packet and also in the process of packet forwarding after route establishment. Saving energy is crucially important to LoWPAN devices that are not mains-powered but have to rely on a depleting source, such as a battery. The lifetime of a LoWPAN node depends on the energy it can store and harvest. Routing protocol design for 6LoWPAN should consider IEEE 802.15.4 link layer feedback on energy consumption. Power-aware routing is a non-trivial task, because it is affected by many mutually conflicting goals: * Minimization of total energy consumed in the network * Maximization of the time until a network partition occurs * Minimizing the energy variance at each node * Minimizing the cost per packet while keeping packet delivery ratio, latency or other requirements depending on each application. Compared to functions such as computational operations or taking sensor samples, radio communications is by far the dominant factor of power consumption [12]. One way of battery lifetime optimization is by achieving a minimal control message overhead. R04: Neighbor discovery for 6LoWPAN routing SHOULD be energy- efficient. Neighbor discovery is a major precondition to allow routing in a network. Especially in a low-power environment, where nodes might be in periodic sleeping states, it is difficult to define whether Kaspar, et al. Expires August 25, 2008 [Page 12] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 a node is a neighbor of another or not. Mesh-under neighbor discovery for 6LoWPANs is currently still in progress and described more detailed in [10]. In case of a route-over protocol, IPv6 neighbor discovery should be operated energy- efficiently. R05: 6LoWPAN routing protocols SHOULD be reliable despite unresponsive nodes. Many nodes in LoWPAN environments might periodically hibernate (i.e. disable their transceiver activity) in order to save energy. Therefore, mesh routing protocols must ensure robust packet delivery despite nodes frequently shutting off their radio transmission interface. Feedback from the lower IEEE 802.15.4 layer may be considered to enhance the power-awareness of 6LoWPAN routing protocols. 4.2. Routing Requirements depending on Types of 6LoWPAN Applications The routing requirements described in this subsection are heavily dependent on application needs. R06: 6LoWPAN routing protocol SHOULD support various traffic patterns. 6LoWPANs mainly have point to multipoint or multipoint to point traffic pattern. Many emerging applications include point to point communication as well. 6LoWPAN routing protocol should be designed with the consideration of forwarding packets from/to multipoint. R07: 6LoWPAN routing protocols SHOULD be robust to dynamic loss rates. An important trait of LoWPAN devices is their unreliability due to limited system capabilities, and also because they might be closely coupled to the physical world with all its unpredictable variation(including RSSI and interference variation), noise, and asynchrony. It is predicted that LoWPANs will be comprised of significantly higher numbers of devices than counted in current networks, causing user interaction and maintenance to become impractical and therefore requiring robustness and self-healing capabilities in their fundamental network structure. The design of mesh routing protocols must consider the fact that packets are to be delivered with reasonable probability despite unreliable and unresponsive nodes. R08: 6LoWPAN routing protocols SHOULD allow for dynamically adaptive Kaspar, et al. Expires August 25, 2008 [Page 13] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 topologies and mobile nodes. There are several challenges that should be addressed by a 6LoWPAN routing protocol in order to create robust routing in dynamic environments: * Mobile nodes changing their location inside a LoWPAN. * Movement of a LoWPAN with respect to other (inter)connected LoWPANs. * Nodes permanently joining or leaving the LoWPAN. * Nodes appearing and disappearing in the network due to changes in the physical environment. When supporting dynamic topologies and mobile nodes, route maintenance should be managed by keeping in mind the goal of a minimal routing state. R09: 6LoWPAN routing protocols SHOULD be scalable. A LoWPAN may consist of just a couple of nodes (for instance in a body-area network), but may expand to much higher numbers of devices (e.g. monitoring of large buildings). It is therefore necessary that routing mechanisms are designed to be scalable for operation in various network sizes. However, due to a lack of memory size and computational power, 6LoWPAN routing might limit forwarding entries to a small number, such as 32 routing table entries. Routing protocols should be designed to achieve both scalability and minimality in terms of used system resources. R10: 6LoWPAN protocol control messages SHOULD be secured. Security threats within LoWPANs may be different from existing threat models in ad-hoc network environments. Neighbor Discovery in IEEE 802.15.4 links may be susceptible to threats as listed in RFC3756 [4]. Bootstrapping may also impose additional threats. Security is also very important for designing robust routing protocols, but it should not cause significant transmission overhead. While there are applications which require very high security, such as in traffic control, other applications are less easily harmed by wrong node behaviour, such as a home entertainment system. Kaspar, et al. Expires August 25, 2008 [Page 14] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 4.3. Mesh-under Specific Requirements The routing requirements described in this subsection allow optimization and correct operation of routing solutions taking into account the specific features of IEEE 802.15.4 physical and MAC layers. R11: 6LoWPAN routing protocol control messages SHOULD not create fragmentation of physical layer (PHY) frames. In order to save energy, routing overhead should be minimized in order to prevent fragmentation of frames on the physical layer (PHY). Therefore, 6LoWPAN routing should not cause packets to exceed the IEEE 802.15.4 frame size. This both reduces the energy required for transmission, avoids unnecessary waste of bandwidth and prevents the need for packet reassembly. R12: For neighbor discovery, 6LoWPAN devices SHOULD avoid sending "Hello" messages. Instead, link-layer mechanisms (such as acknowledgments or beacon responses) MAY be utilized to keep track of active neighbors. R13: In order to find energy-optimal routing paths, LoWPAN mesh routing protocols should minimize power consumption by utilizing a combination of the link quality indication (LQI) provided by the MAC layer and other measures, such as hop count. Variability of LQI with time should be considered. R14: The procedure of local repair and related control messages should not harm overall energy consumption from the routing protocols. Local repair (when possible) can help reducing loss rates, end-to-end delivery delays, and in successful cases a reduction of control overhead. R15: In case a routing protocol operates in 6LoWPAN's adaptation layer, then routing tables and neighbor lists SHOULD support 16-bit short and 64-bit extended addresses. Kaspar, et al. Expires August 25, 2008 [Page 15] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 5. Security Considerations Security issues are described in Section 4 Kaspar, et al. Expires August 25, 2008 [Page 16] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 6. Acknowledgements The authors would like to thank Myung-Ki Shin for giving the idea of writing this draft. Kaspar, et al. Expires August 25, 2008 [Page 17] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 7. References 7.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On-Demand Distance Vector (AODV) Routing", RFC 3561, July 2003. [3] Clausen, T. and P. Jacquet, "Optimized Link State Routing Protocol (OLSR)", RFC 3626, October 2003. [4] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor Discovery (ND) Trust Models and Threats", RFC 3756, May 2004. [5] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals", RFC 4919, August 2007. [6] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC 4944, September 2007. [7] IEEE Computer Society, "IEEE Std. 802.15.4-2003", October 2003. [8] IEEE Computer Society, "IEEE Std. 802.15.4-2006", September 2006. 7.2. Informative References [9] Bulusu, N. and S. Jha, "Wireless Sensor Networks", July 2005. [10] Chakrabarti, S. and E. Nordmark, "LoWPAN Neighbor Discovery Extensions, draft-chakrabarti-6lowpan-ipv6-nd-04 (work in progress)", November 2007. [11] Chakeres, I. and C. Perkins, "Dynamic MANET On-demand (DYMO) Routing, draft-ietf-manet-dymo-12 (work in progress)", June 2005. [12] Pister, K. and B. Boser, "Smart Dust: Wireless Networks of Millimeter-Scale Sensor Nodes". Kaspar, et al. Expires August 25, 2008 [Page 18] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 Authors' Addresses Dominik Kaspar Simula Research Laboratory Martin Linges v 17 Snaroya 1367 Norway Phone: +47-6782-8387 Email: dokaspar.ietf@gmail.com Eunsook Kim ETRI 161 Gajeong-dong Yuseong-gu Daejeon 305-700 Korea Phone: +82-42-860-6124 Email: eunah.ietf@gmail.com Carles Gomez Technical University of Catalonia (UPC) Escola Politecnica Superior de Castelldefels Avda. del Canal Olimpic, 15 Castelldefels 08860 Spain Phone: +34-93-413-7206 Email: carlesgo@entel.upc.edu Carsten Bormann Universitaet Bremen TZI Postfach 330440 Bremen D-28359 Germany Phone: +49-421-218-7024 Fax: +49-421-218-7000 Email: cabo@tzi.org Kaspar, et al. Expires August 25, 2008 [Page 19] Internet-Draft 6LoWPAN Mesh Routing Requirements February 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. 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, THE IETF TRUST 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. Intellectual Property 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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Kaspar, et al. Expires August 25, 2008 [Page 20]