Network Working Group D. Meyer Internet-Draft October 14, 2005 Expires: April 17, 2006 Terminology for Describing VoIP Peering and Interconnect draft-meyer-voipeer-terminology-00.txt 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 17, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document defines the terminology that is to be used by the Voice Over IP Peering and Interconnect (voipeer) Working Group, and should be used to focus the voipeer Working Group during discussions and when writing requirements, gap analysis and other solutions oriented documents. Meyer Expires April 17, 2006 [Page 1] Internet-Draft Terminology for Describing VoIP Peering October 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. General Definitions . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Call Routing Data (CRD) . . . . . . . . . . . . . . . . . . 4 3.2. Call Routing . . . . . . . . . . . . . . . . . . . . . . . 4 3.3. PSTN . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.4. Network . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.5. VoIP Service Provider . . . . . . . . . . . . . . . . . . . 5 3.6. Carrier . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.7. Peering . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.8. Layer 3 Peering . . . . . . . . . . . . . . . . . . . . . . 5 3.9. Layer 5 Peering . . . . . . . . . . . . . . . . . . . . . . 5 3.10. VoIP Peering . . . . . . . . . . . . . . . . . . . . . . . 6 4. ENUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. User ENUM . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. Carrier ENUM . . . . . . . . . . . . . . . . . . . . . . . 6 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Meyer Expires April 17, 2006 [Page 2] Internet-Draft Terminology for Describing VoIP Peering October 2005 1. Introduction The term "VoIP Peering" has historically been used to describe a wide variety of different aspects pertaining to the interconnection of service provider networks, and to the delivery of SIP call termination over those interconnections. Further, since VoIP peering focuses on how to identify and route calls at the application level ("Layer 5"), it does not (necessarily) involve the exchange of packet routing data or even media sessions. In particular, "layer 5 network" is used here to refer to the interconnection between SIP servers (as opposed to interconnection at the IP layer). Finally, the terms "peering" and "interconnect" are used interchangeably throughout this document. This document introduces standard terminology for use in characterizing VoIP interconnection. Note however, that while this document is primarily targeted at the VoIP interconnect case, the terminology described here is applicable to those cases in which service providers interconnect using SIP signaling for real-time or quasi-real-time communications. The remainder of this document is organized as follows: Section 2 provides the general context for voipeer, and Section 3 provides the general definitions for real-time SIP based communication, with focus on the VoIP interconnect case. Section 4 briefly touches on terms from ENUM. Finally, Section 5 provides comments on usage. 2. Context Figure 1 depicts the general VoIP interconnect context in which the caller uses an E.164 number [ITU.E164.1991] as the "name" of the called user. Note that this E.164 number is not an address, since at this point we do not have information about where the named endpoint is located. In the case shown here, an E.164 number is used as a key to retrieve a NAPTR [RFC3404] record from the DNS, which in turn results in a SIP URI. Call routing is then based on this SIP URI. Note call routing does not depend on the presence of an E.164 number; the SIP URI can be advertised in various other ways, such as on a web page. Finally, note that the subsequent lookup steps, namely, look up of SRV, A, and AAAA records (as well as any routing steps below that) are outside the scope of voipeer. Meyer Expires April 17, 2006 [Page 3] Internet-Draft Terminology for Describing VoIP Peering October 2005 E.164 number <--- Peer Discovery | | <--- ENUM lookup of NAPTR in DNS | SIP URI <--- Call Routing Data (CRD) | | <--- Service Location (Lookup of SRV in DNS) | Hostname <--- VoIP addressing and session establishment | | <---- Lookup of A and AAAA in DNS | Ip address | | <---- Routing protocols, ARP etc | Mac-address Figure 1: VoIP Interconnect Context Note that voipeer is primarily concerned with the acquisition and use of the Call Routing Data (CRD) shown in in Figure 1. Importantly, the CRD can be derived from an E.164 entry, as shown in Figure 1, or via any other mechanism available to the user. 3. General Definitions 3.1. Call Routing Data (CRD) Call Routing Data, or CRD, is a SIP URI used to route a (real-time, voice or other type) call to its termination point. [ed: do we need a definition of "termination point"?] 3.2. Call Routing Call routing is the set of processes, rules, and CRD used to route a VoIP call to its proper (SIP) destination. More generally, it is the set of processes, rules and CRD used to route a real-time session to its termination point. 3.3. PSTN The term "PSTN" refers to the Public Switched Telephone Network. In particular, the PSTN refers to the collection of interconnected circuit-switched voice-oriented public telephone networks, both commercial and government-owned. In general, PSTN terminals are Meyer Expires April 17, 2006 [Page 4] Internet-Draft Terminology for Describing VoIP Peering October 2005 addressed using E.164 numbers, noting that various dial-plans (such as emergency services dial-plans) may not directly use E.164 numbers. 3.4. Network For purposes of this document and the voipeer work, a network is defined to be the set of SIP servers and customers that are controlled by a single administration. 3.5. VoIP Service Provider A VoIP service provider is an entity that provides transport of SIP signaling and possibly media streams for its customers. Such a service provider may additionally be interconnected with other service providers (i.e., it may "peer" Section 3.7 with other service providers). Note that a VoIP service provider may also interconnect with the PSTN. 3.6. Carrier The term carrier is defined to be a service provider authorized to issue E.164 numbers [ITU.E164.1991] for the provisioning of PSTN service under the authority of a National Regulatory Authority (NRA). noting also that the term "carrier" has both business and regulator connontations... 3.7. Peering While the precise definition of the term "peering" is the subject of some debate, peering in general refers to the negotiation of reciprocal interconnection arrangements, settlement-free or otherwise, between operationally independent service providers. 3.8. Layer 3 Peering Layer 3 peering refers to interconnection of two service providers for the purposes of exchanging IP packets. Layer 3 peering is frequently agnostic to the IP payload, and is frequently achieved using a routing protocol such as BGP [RFC1771] to exchange the required routing information. 3.9. Layer 5 Peering Layer 5 peering refers to interconnection of two service providers for the purposes of SIP signaling. Note that in the layer 5 peering case, there is no intervening network. That is, for purposes of this discussion, there is no such thing as a "Layer 5 Transit Network". Meyer Expires April 17, 2006 [Page 5] Internet-Draft Terminology for Describing VoIP Peering October 2005 3.10. VoIP Peering VoIP peering is defined to be a layer 5 peering between two VoIP providers for purposes of routing real-time (or quasi-real time) call signaling between their respective customers. 4. ENUM ENUM [RFC3761] defines how the Domain Name System (DNS) can be used for identifying available services connected to one E.164 number. 4.1. User ENUM 4.2. Carrier ENUM 5. Conclusions 6. Acknowledgments Many of the definitions were gleaned from detailed discussions on the voipeer, enum, and sipping mailing lists. Richard Shocky and Jean- Francois Mule made valuable contributions to early revisions of this document. Patrik Faltstrom contributed the basis of Figure 1. 7. Security Considerations This document itself introduces no new security considerations. However, it is important to note that VoIP interconnect has a wide variety of security issues that should be considered in documents addressing both protocol and use case analyzes. 8. IANA Considerations This document creates no new requirements on IANA namespaces [RFC2434]. 9. References 9.1. Normative References [RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", Meyer Expires April 17, 2006 [Page 6] Internet-Draft Terminology for Describing VoIP Peering October 2005 RFC 3404, October 2002. [RFC3761] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC 3761, April 2004. [ITU.E164.1991] International Telecommunications Union, "The International Public Telecommunication Numbering Plan", ITU- T Recommendation E.164, 1991. 9.2. Informative References [RFC1771] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Meyer Expires April 17, 2006 [Page 7] Internet-Draft Terminology for Describing VoIP Peering October 2005 Author's Address David Meyer Email: dmm@1-4-5.net Meyer Expires April 17, 2006 [Page 8] Internet-Draft Terminology for Describing VoIP Peering 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. 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