Network Working Group D. Meyer Internet-Draft August 7, 2006 Expires: February 8, 2007 SPEERMINT Terminology draft-ietf-speermint-terminology-02.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 February 8, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document defines the terminology that is to be used by the Session PEERing for Multimedia INTerconnect Working Group (SPEERMINT). It has as its primary objective to focus the working group during its discussions, and when writing requirements, gap analysis and other solutions oriented documents. Meyer Expires February 8, 2007 [Page 1] Internet-Draft SPEERMINT Terminology August 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. SPEERMINT Context . . . . . . . . . . . . . . . . . . . . . . 3 3. General Definitions . . . . . . . . . . . . . . . . . . . . . 4 3.1. Call Routing Data . . . . . . . . . . . . . . . . . . . . 4 3.2. Call Routing . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. PSTN . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.4. Network . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.5. Service Provider (SP) . . . . . . . . . . . . . . . . . . 5 3.6. Voice Service Provider (VSP) . . . . . . . . . . . . . . . 5 4. Peering . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Layer 3 Peering . . . . . . . . . . . . . . . . . . . . . 6 4.2. Layer 5 (Session) Peering . . . . . . . . . . . . . . . . 6 4.3. Direct Peering . . . . . . . . . . . . . . . . . . . . . . 6 4.4. Indirect (Transit) Peering . . . . . . . . . . . . . . . . 6 5. ENUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1. Carrier of Record . . . . . . . . . . . . . . . . . . . . 7 5.2. User ENUM . . . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Infrastructure ENUM . . . . . . . . . . . . . . . . . . . 8 6. Federations . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Federation Functionality . . . . . . . . . . . . . . . . . 9 6.2. Announcement of Federation Membership . . . . . . . . . . 9 6.3. Example Federation Rules . . . . . . . . . . . . . . . . . 10 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 10.1. Normative References . . . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 12 Meyer Expires February 8, 2007 [Page 2] Internet-Draft SPEERMINT Terminology August 2006 1. Introduction The term "VoIP Peering" has historically been used to describe a wide variety of aspects pertaining to the interconnection of service provider networks and to the delivery of SIP call termination over those interconnections. The discussion of these interconnections has at times been confused by the fact that the term "peering" is used in various contexts to relate to interconnection at different levels in a protocol stack. Session Peering for Multimedia Interconnect focuses on how to identify and route real-time sessions (such as VoIP calls) at the application layer, and it does not (necessarily) involve the exchange of packet routing data or 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 ("layer 3"). Finally, the terms "peering" and "interconnect" are used interchangeably throughout this document. This document introduces standard terminology for use in characterizing real-time session 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 the SPEERMINT Working Group. Section 3 provides the general definitions for real-time SIP based communication, with initial focus on the VoIP interconnect case, and Section 5 briefly touches on terms from the ENUM Working Group. Finally, Section 6 introduces the concept of federations. 2. SPEERMINT Context Figure 1 depicts the general VoIP interconnect context. In the case shown here, an E.164 number [ITU.E164.1991] is used as a key by ENUM to retrieve a NAPTR record [RFC3404] from the DNS, which in turn resolved into a SIP URI. Call routing is based on the resulting SIP URI. The call routing step does not depend on the presence of an E.164 number; indeed, the resulting SIP URI may no longer even contain any numbers, and the SIP URI can be advertised in various other ways, such as on a web page. Meyer Expires February 8, 2007 [Page 3] Internet-Draft SPEERMINT Terminology August 2006 E.164 number <--- Peer Discovery | | <--- ENUM lookup of NAPTR in DNS | | | ENUM Working Group Scope =====+==================================================== | SPEERMINT Working Group Scope | SIP URI <--- Call Routing Data (CRD) | | | <--- Federation Detection, Policy | Lookup, and Service Location | | Hostname <--- Addressing and session establishment | | SPEERMINT Working Group Scope =====+==================================================== | Out of scope for the SPEERMINT Working Group | | <--- Lookup of A and AAAA in DNS | Ip address | | <--- Routing protocols, ARP etc | Mac-address Figure 1: Session Interconnect Context The ENUM Working Group is primarily concerned with the acquisition of Call Routing Data, or CRD (i.e., above the double line in Figure 1), while the SPEERMINT Working Group is focused on the use of such CRD. Importantly, the CRD can be derived from ENUM (i.e., an E.164 DNS entry), or via any other mechanism available to the user. 3. General Definitions 3.1. Call Routing Data Call Routing Data, or CRD, is a SIP URI used to route a call (real- time, voice or other type) to the called domain's ingress point. A domain's ingress point can be thought of as the location pointed to by the SRV record that resulted from the resolution of the CRD (i.e., a SIP URI). Meyer Expires February 8, 2007 [Page 4] Internet-Draft SPEERMINT Terminology August 2006 3.2. Call Routing Call routing is the set of processes, rules, and CRD used to route a call to its proper (SIP) destination. More generally, call routing can be thought of as the set of processes, rules and CRD which are used to route a real-time session to its termination (ingress) 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 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 SPEERMINT and ENUM Working Groups, a network is defined to be the set of SIP servers and end- users (customers) that are controlled by a single administrative domain and can be reached via layer 3 (IP) peering. The network may also contain end-users who are located on the PSTN, as long as they are also reachable via layer 3 (IP) peering. 3.5. Service Provider (SP) A Service Provider (or SP) is defined to be an entity that controls a "network" as defined in Section 3.4, and provides transport of SIP signaling and media packets. 3.6. Voice Service Provider (VSP) A Voice Service Provider (or VSP) is an entity that provides transport of SIP signaling (and possibly media streams) to its customers. Such a service provider may additionally be interconnected with other service providers; that is, it may "peer" with other service providers. A VSP may also interconnect with the PSTN. Note that as soon as a ingress point is advertised via a SRV record, anyone can find that ingress point and hence can send calls there. This is very similar to sending mail to a SMTP server based on the existence of a MX record. Finally, note the concept of a VSP is a subset of the possible SP types. That is, a VSP is an SP, but it is not necessary that an SP be a VSP. Meyer Expires February 8, 2007 [Page 5] Internet-Draft SPEERMINT Terminology August 2006 4. Peering While the precise definition of the term "peering" is the subject of considerable debate, peering in general refers to the negotiation of reciprocal interconnection arrangements, settlement-free or otherwise, between operationally independent service providers. This document distinguishes two types of peering, Layer 3 Peering and Layer 5 peering, which are described below. 4.1. Layer 3 Peering Layer 3 peering refers to interconnection of two service providers for the purposes of exchanging IP packets which destined for one (or both) of the peer's networks. Layer 3 peering is generally agnostic to the IP payload, and is frequently achieved using a routing protocol such as BGP [RFC1771] to exchange the required routing information. An alternate, perhaps more operational definition of layer 3 peering is that two peers exchange only customer routes, and hence any traffic between peers terminates on one of the peer's network. 4.2. Layer 5 (Session) Peering Layer 5 (Session) peering refers to interconnection of two service providers for the purposes of routing real-time (or quasi-real time) secure call signaling between their respective customers using SIP methods. Such interconnection may be direct or indirect (see Section 4.3 and Section 4.4 below). Note that media streams associated with this signaling (if any) are not constrained to follow the same set of paths. 4.3. Direct Peering Direct peering describes those cases in which two domains interconnect without using an intervening layer 5 network. Both domains must have a trust relationship established (for example, they may know they belong to the same federation; see Section 6 below) before opening up a secure layer 5 communication path. 4.4. Indirect (Transit) Peering Indirect (transit) peering refers to the establishment of a secure signaling path via one (or more) referral or transit network(s). In this case it is required that a trust relationship is established between the originating domain and the transit network on one side, and the transit network and the termination network on the other Meyer Expires February 8, 2007 [Page 6] Internet-Draft SPEERMINT Terminology August 2006 side. Both trust relationships must exist before opening up a secure communication path on L5. 5. ENUM ENUM [RFC3761] defines how the Domain Name System (DNS) can be used for identifying available services connected to one E.164 number. 5.1. Carrier of Record For purposes of this document, "Carrier of Record", or COR, refers to the entity to which an E.164 number has been assigned to (or ported to). More specifically, the COR can be defined can defined as follows [I-D.ietf-enum-infrastructure-enum-reqs]: o If the number in question has not been ported, then the COR is the Service Provider to which the E.164 number was allocated for end user assignment (either the National Regulatory Authority (NRA) or the International Telecommunication Union (ITU) makes these assignments), or o If the number has been ported, the COR is the service provider to which the number was ported, or o If the number is assigned directly to end users, the COR is the service provider that the end user number assignee has chosen to provide a Public Switched Telephone Network/Public Land Mobile Network (PSTN/PLMN) point-of-interconnect for the number. Finally, note that the exact definition of who and what is a COR is ultimately the responsibility of the relevant NRA. 5.2. User ENUM User ENUM is generally defined as the set of administrative policies and procedures surrounding the use of the e164.arpa domain for Telephone Number to URI resolution [RFC3761]. In the User ENUM case, the entity (or person) having the right to use a number has control the content of the associated domain and thus the zone content (at the very least, there is local control over the content of the zone). From a domain registration perspective, the end user number assignee is thus the registrant [I-D.ietf-enum-infrastructure-enum-reqs]. Policies and procedures for the registration of telephone numbers within all branches of the e164.arpa tree are Nation State issues by agreement with the Internet Architecture Board (IAB) and ITU. National Regulatory Authorities have generally defined User ENUM Meyer Expires February 8, 2007 [Page 7] Internet-Draft SPEERMINT Terminology August 2006 Registrants as the E.164 number holder as opposed to the COR that issued the phone number. 5.3. Infrastructure ENUM Infrastructure ENUM (I-ENUM) is generally regarded as the use of a separate branch the e164.arpa tree, such as ie164.arpa to permit service providers to exchange phone number to URI data in order to find points of interconnection. The current theory of Infrastructure ENUM is that only the COR for a particular E.164 number is permitted to provision data for that E.164 within that portion of the e164.arpa tree. In infrastructure ENUM, only the COR may enter data in the corresponding domain. The COR may also enter CRD (i.e., a SIP URI) to allow other SPs to to route sessions to its network. Finally, note that ENUM is not constrained to carry only data (CDR) as defined by SPEERMINT. In particular, an important class of CRD, the tel URIs [RFC3966] may be carried in ENUM. Such tel URIs are most frequently used to interconnect with the PSTN directly, and are out of scope for SPEERMINT. On the other hand, PSTN endpoints served by a COR and reachable via CDR and networks as defined in Section 3.1 and Section 3.4 are in scope for SPEERMINT. 6. Federations The domain policy DDDS application [I-D.lendl-domain-policy-ddds] defines a method with which a domain owner can announce the policy it will use to accept incoming calls. This section introduces a policy type for use with that framework, known as federations [I-D.lendl-speermint-federations]. Note that [I-D.lendl-domain-policy-ddds] does not define what these rules can be or how they might be communicated to the members of a federation. Further, there is no requirement that such rules are in any way public. Briefly, a federation is a group of SPs which agree: * To receive calls from each other via SIP, * On a set of administrative rules for such calls (settlement, abuse-handling, ...), and * On specific rules for the technical details of the interconnection. Meyer Expires February 8, 2007 [Page 8] Internet-Draft SPEERMINT Terminology August 2006 6.1. Federation Functionality A federation may provide some or all of the following functionality: * Common policies + Policy might be ah-hoc, and published in the DNS (e.g., [I-D.lendl-domain-policy-ddds], or + Policy might also be managed by a federation entity * A federated ENUM root * Address resolution mechanisms * Session signaling (via federation policy) * Media streams (via federation policy) * Federation security policies * Interconnection policies * Other layer 2 and layer 3 policies Finally, note that a SP can be a member of * No federation (e.g., the SP has only bilateral peering agreements) * A single federation * Multiple federations and an SP can have any combination of bi-lateral and multi-lateral (i.e., federated) interconnections. 6.2. Announcement of Federation Membership Announcement of federation membership is typically made by the terminating SP, using one or more of the following mechanisms: * I-ENUM * A Private ENUM Federation discovery mechanism * DNS Meyer Expires February 8, 2007 [Page 9] Internet-Draft SPEERMINT Terminology August 2006 6.3. Example Federation Rules Example federation rules might include the following: o A set of SPs form an association and agree to accept calls from each other via the public Internet as long as the SIP call uses TCP/TLS as transport protocol and presents a X.509 cert which was signed by the association's own CA. o A set of SPs build a L3 network dedicated to VoIP peering (e.g., the 3GPP GRX). The further agree to accept calls from all participants in that network and bill each other via a clearinghouse. o A set of SPs agree to accept calls originating from within the same country. They use a set of firewall rules to block calls from abroad. o A company sets up a SIP proxy which acts as a forwarding proxy between the SIP proxies of all participating SPs. The group of these SP form a federation whose technical rules state that calls have to be routed via that central proxy. 7. Acknowledgments Many of the definitions were gleaned from detailed discussions on the SPEERMINT, ENUM, and SIPPING mailing lists. Scott Brim, Eli Katz, Mike Hammer, Gaurav Kulshreshtha, Jason Livingood, Jean-Francois Mule, David Schwartz, Richard Shockey, Henry Sinnreich, Richard Stastny, Dan Wing, and Adam Uzelac all made valuable contributions to early versions of this document. Patrik Faltstrom also made many insightful comments to early versions of this draft, and contributed the basis of Figure 1. 8. Security Considerations This document introduces no new security considerations. However, it is important to note that Session interconnect, as described in this document, has a wide variety of security issues that should be considered in documents addressing both protocol and use case analyzes. 9. IANA Considerations This document creates no new requirements on IANA namespaces Meyer Expires February 8, 2007 [Page 10] Internet-Draft SPEERMINT Terminology August 2006 [RFC2434]. 10. References 10.1. Normative References [RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", 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. [RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, December 2004. 10.2. 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. [I-D.ietf-enum-infrastructure-enum-reqs] Lind, S. and P. Pfautz, "Infrastrucure ENUM Requirements", draft-ietf-enum-infrastructure-enum-reqs-02 (work in progress), April 2006. [I-D.lendl-speermint-federations] Lendl, O., "A Federation based VoIP Peering Architecture", draft-lendl-speermint-federations-01 (work in progress), June 2006. [I-D.lendl-domain-policy-ddds] Lendl, O., "The Domain Policy DDDS Application", draft-lendl-domain-policy-ddds-01 (work in progress), June 2006. Meyer Expires February 8, 2007 [Page 11] Internet-Draft SPEERMINT Terminology August 2006 Author's Address David Meyer Email: dmm@1-4-5.net Full Copyright Statement Copyright (C) The Internet Society (2006). 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 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. Meyer Expires February 8, 2007 [Page 12] Internet-Draft SPEERMINT Terminology August 2006 Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Meyer Expires February 8, 2007 [Page 13]