DNA Working Group Yong-Geun Hong INTERNET DRAFT Jung-Soo Park Expires: April 2005 Hyoung-Jun Kim ETRI October 2004 Considerations for DNA Schemes with Multiple Interfaces and Layer 2 Technologies Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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 docu- ments at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in pro- gress." 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 2005. Abstract In this document we consider and analyze various environments for applying Detecting Network Attachment (DNA) schemes. Although DNA schemes are typically run for each interface and a host separately checks for link changes on each interface when the host has multiple interfaces, DNA schemes in the host must be considered to check the multiple interfaces at the same time for a seamless service. In addition, DNA schemes in the host must be capable of managing together each DNA scheme on each interface. Current DNA schemes only rely on "Break before Make" L2 technology such as 802.11. But now and in future, there will be other "Make before break" L2 technologies such as CDMA. In these L2 technologies, DNA schemes must be operated differently in order to make use of their characteristics. Hong, Park, Kim Expires April 2005 [Page 1] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 Table of Contents: 1. Introduction................................................2 2. Terminology.................................................3 3. Various cases with Interfaces and Layer 2 Technology........3 3.1 Case : Single Interface with Break before Make.............4 3.2 Case : Single Interface with Make before Break.............4 3.3 Case : Multiple Interfaces with Break before Make..........4 3.4 Case : Multiple Interfaces with Make before Break..........5 4. Security Considerations.....................................5 5. Acknowledgments.............................................5 6. References..................................................6 Author's Addresses.............................................6 1. Introduction In fixed wire networks, when communication failure happens, it is expected that there are physical or link-layer errors. Change of the link-layer seldom happens. But in wireless and mobile networks, communication failures are caused by many reasons. Not only physical errors, but also the out of range of Access Point coverage and movement between networks (links) are important factors for communication failures. Detecting Network Attachment (DNA) is proposed for solving the above problem, for movement between networks (links). To do this, DNA schemes detect the identity of the currently attached link to ascertain the validity of the existing IP configuration [3]. DNA schemes are typically run for each interface and a host separately checks for link changes on each interface when the host has multiple interfaces [3]. In future ubiquitous networks, many services and various technologies are expected to be inter-worked and harmonized for a better and seamless service. Wired and wireless technologies are expected to be coupled and it is the same for different wireless technologies. As various wireless technologies are introduced, a host having multiple interfaces has appeared. The multiple interfaces may be the same technology or a different technology such as WLAN/CDMA, WLAN/GPRS. In this multiple interface host, DNA schemes must be considered to check the multiple interfaces at the same time for a seamless service and to manage together each DNA scheme on each interface. Current link-layer technologies which DNA schemes are operated on are 802.3 Ethernet or 802.11 wireless LAN technologies. The characteristics of these link-layer technologies are that a new link-layer connection is made only after an old link-layer connection is torn down. Also in these link-layer technologies, a Hong, Park, Kim Expires April 2005 [Page 2] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 host does not have any information about a new link until a new link-layer connection is established. The only way to recognize information about the new link is to receive link information (e.g. Router Advertisement message) only after a new link-layer connection is made [1,2]. Because other link-layer technologies such as CDMA have the ability to make a new link-layer connection before an old link-layer connection is torn down, a host may know new link information before a new link-layer connection is established [7]. In these link-layer technologies, current DNA schemes may not be the proper solution to handle link change. It needs other features of DNA schemes to support this characteristic. This document identifies various cases for applying DNA schemes. We consider and analyze various environments according to whether multiple interfaces are supported and the characteristics of link- layer technologies. 2. Terminology This document identifies various cases for applying DNA schemes. We consider and analyze various environments according to whether multiple interfaces are supported and the characteristics of link- layer technologies. Following are two typical characteristics of L2 technologies : Break before Make The characteristic of link-layer technology where a new link- layer connection can be made only after an old link-layer connection is disconnected. In this link-layer technology, new link information can be acquired only after a new link- layer connection is made, that is only after an old link- layer connection is torn down. Make before Break The characteristic of link-layer technology where a new link- layer connection can be made before an old link-layer connection is disconnected. In this link-layer technology, new link information can be acquired before a new link-layer connection is made, that is before an old link-layer connection is torn down. 3. Various cases with Interfaces and Layer 2 Technology In this section, we classify cases for applying DNA schemes whether a host has a single interface or multiple interfaces and whether link-layer technology are Break before Make or Make before Break. Hong, Park, Kim Expires April 2005 [Page 3] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 3.1 Case : Single Interface with Break before Make It is the typical case where we are currently using a 802.11 wireless LAN. In this case, a new link-layer connection is established to a new access point only after an old link-layer connection is disconnected. Two different link-layer connections cannot be established simultaneously. In this case, link information can be acquired only after a new link-layer connection is established. Only after a new link-layer connection is made, a host can collect the appropriate information and detects the identity of its currently attached link to ascertain the validity of its IP configuration [3]. In this case, the focus of DNA schemes is that how can a host receive link information in a fast and effective method. To do this, until now, there are many proposed mechanisms. [4,5,6] 3.2 Case : Single Interface with Make before Break We think that we are not familiar with this case. But in CDMA[7], a mobile station can access two or more different base stations simultaneously. In this case, a host can make a new link-layer connection before an old link-layer connection is torn down. In this case, a host can acquire new link information through a new link-layer connection before an old link-layer connection is torn down. A difference from the above case (Section 3.1) is that a host can acquire link information over a new link-layer connection while keeping an old existing link-layer connection. In this case, the focus of DNA schemes may be different from the above case. We think that DNA schemes should have the ability to handle this difference. 3.3 Case : Multiple Interfaces with Break before Make As various wireless technologies are introduced, a host has a chance to have multiple interfaces. Link-layer technologies of each multiple interface may be the same (e.g. all of them are 802.11) or different (e.g. one of them is 802.11 and one of them is CDMA / GPRS) If each link-layer technology of each interface is the same and each interface is in the same link, this scenario may not be very much different with case 3.1. Because each interface is in the same link, link information on each interface may be the same. In this scenario, multiple interfaces do not have any effect on detecting any link changes. Hong, Park, Kim Expires April 2005 [Page 4] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 But, if each link-layer technology of each interface is the same and each interface is in a different link (although this scenario may not be common), a host must have the ability to manage each interface and its link information on each interface. In this scenario, when a host detects a link-layer change, it can use other link information to support a seamless service, or the host can follow general DNA schemes on the interface where a link-layer change happens. If each link-layer technology of each interface is different, situations may be different from the above two scenarios. If each interface is in the same link, one link-layer change on one interface does not mean the link changes. The reason is that each interface has different characteristics for its link-layer technology (e.g. the service coverage area of each access point may be different). Also each interface is in different links, one link-layer change on one interface does not mean the link changes. In these scenarios, a host must have the ability to manage each interface and tis link information. There may be other considerations to make use of these scenarios. 3.4 Case : Multiple Interfaces with Make before Break If a host has multiple interfaces and each link-layer connection is operated on the make before break method, DNA schemes may be operated differently. Because a new link-layer connection can be made before an old link-layer connection is disconnected and a host has multiple interfaces, it can keep link information on another interface in spite of a link-layer change of one interface. In this case, we think that the scenario where each link-layer technology of each interface is different may not exist. To support the make before break method on multiple interfaces, each link- layer technology must be the same. 4. Security Considerations This document discusses considerations for applying DNA schemes on various environments. The associated security issues will be identified as further work goes on. 5. Acknowledgements We would like to express our sincere appreciation to Do-Wan Kim, Tony Bonanno for their valuable comments in improving this draft. Hong, Park, Kim Expires April 2005 [Page 5] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 6. References Normative [1] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [2] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. Informative [3] Choi, J. and G. Daley, "Detecting Network Attachment in IPv6 Goals", draft-ietf-dna-goals-02.txt (work in progress), September 2004. [4] Choi, J. and D. Shin, "Fast Router Discovery with RA Caching in AP", draft-jinchoi-mobileip-frd-00 (work in progress), February 2003. [5] Kempf, J., Khalil, M. and B. Pentland, "IPv6 Fast Router Advertisement", draft-mkhalil-ipv6-fastra-02 (work in progress), October 2002. [6] Daley, G., Pentland, B. and E. Nordmark, "Deterministic Fast Router Advertisement Options", draft-daley-dna-det-fastra-00 (work in progress), July 2004. [7] TIA/EIA/IS-2000 Series, "CDMA 2000 Series, Release A (2000)" Authors' Addresses Yong-Geun Hong ETRI PEC 161 Gajeong-Dong, Yuseong-Gu, Daejeon 305-350, Korea Phone: +82 42 860 6557 Email: yghong@pec.etri.re.kr Jung-Soo Park ETRI PEC 161 Gajeong-Dong, Yuseong-Gu, Daejeon 305-350, Korea Phone: +82 42 860 6514 Email: jspark@pec.etri.re.kr Hyoung-Jun Kim ETRI PEC 161 Gajeong-Dong, Yuseong-Gu, Daejeon 305-350, Korea Phone: +82 42 860 6576 Email: khj@etri.re.kr Hong, Park, Kim Expires April 2005 [Page 6] INTERNET-DRAFT DNA with Consideraing IF and L2 October 2004 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. 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