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Versions: (draft-ietf-speermint-reqs-and-terminology) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 RFC 5486

Network Working Group                                           D. Meyer
Internet-Draft                                             July 18, 2006
Expires: January 19, 2007


                         SPEERMINT Terminology
                draft-ietf-speermint-terminology-01.txt

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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.







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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
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  9
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
     10.2. Informative References . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
   Intellectual Property and Copyright Statements . . . . . . . . . . 11






















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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.









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           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).



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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.



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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



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   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 that provides PSTN service for an E.164 number.  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 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 the controls
   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



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   Registrants as the E.164 number holder as opposed to the COR that
   issued the phone number.

5.3.  Infrastructure ENUM

   Infrastructure ENUM (also called Carrier ENUM) is generally regarded
   as the use of a separate branch the e164.arpa tree, such as
   i.e164.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 calls to its network.

   Finally, note that ENUM is not constrained to carry only data (CDR)
   as defined by SPEERMINT.  In particular, an 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].

   Briefly, a federation is a group of SPs which agree:

   o  To receive calls from each other via SIP,

   o  On a set of administrative rules for such calls (settlement,
      abuse-handling, ...), and

   o  On specific rules for the technical details of the
      interconnection.

   [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.



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   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, Mike Hammer,
   Gaurav Kulshreshtha, Jason Livingood, Jean-Francois Mule, David
   Schwartz, Richard Shockey, Henry Sinnreich, Richard Stastny, and Dan
   Wing all made valuable contributions to early revisions 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
   [RFC2434].





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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.








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Author's Address

   David Meyer

   Email: dmm@1-4-5.net


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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.















































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