Network Working Group D. Meyer
Internet-Draft September 18, 2006
Intended status: Informational
Expires: March 22, 2007
SPEERMINT Terminology
draft-ietf-speermint-terminology-06.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 March 22, 2007.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines the terminology that is to be used in
describing Session PEERing for Multimedia INTerconnect (SPEERMINT).
Meyer Expires March 22, 2007 [Page 1]
Internet-Draft SPEERMINT Terminology September 2006
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. SPEERMINT Context . . . . . . . . . . . . . . . . . . . . . . 3
3. General Definitions . . . . . . . . . . . . . . . . . . . . . 5
3.1. Signaling Path Border Element . . . . . . . . . . . . . . 5
3.2. Data Path Border Element . . . . . . . . . . . . . . . . . 5
3.3. Call Addressing Data . . . . . . . . . . . . . . . . . . . 5
3.4. Call Routing . . . . . . . . . . . . . . . . . . . . . . . 6
3.5. PSTN . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.6. IP Path . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.7. Peer Network . . . . . . . . . . . . . . . . . . . . . . . 6
3.8. Service Provider . . . . . . . . . . . . . . . . . . . . . 6
3.9. Voice Service Provider . . . . . . . . . . . . . . . . . . 6
3.10. Internet Telephony Service Provider . . . . . . . . . . . 7
4. Peering . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Layer 3 Peering . . . . . . . . . . . . . . . . . . . . . 7
4.2. Layer 5 Peering . . . . . . . . . . . . . . . . . . . . . 7
4.2.1. Direct Peering . . . . . . . . . . . . . . . . . . . . 8
4.2.2. Indirect Peering . . . . . . . . . . . . . . . . . . . 8
4.2.3. Assisted Peering . . . . . . . . . . . . . . . . . . . 8
5. Federations . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Informative References . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 11
Meyer Expires March 22, 2007 [Page 2]
Internet-Draft SPEERMINT Terminology September 2006
1. Introduction
The term "Voice over IP Peering" (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
Session Initial Protocol (SIP [RFC3261]) 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 non-
voice 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 4 defines the terminology describing the various forms of
peering. Finally, Section 5 introduces the concept of federations.
2. SPEERMINT Context
Figure 1 depicts the general session interconnect context. Note that
vertical axis in this figure describes the layering of identifiers,
while the horizontal lines indicate working group scope. While the
SPEERMINT working group is not limited (or coupled in any way) to the
use of E.164 numbers, in the case shown here an E.164 number
[ITU.E164.2005] is used as a key in an E.164 to Uniform Resource
Identifier (URI) mapping (ENUM [RFC3761]). That URI is in turn used
to retrieve a NAPTR record [RFC3404], which is in turn resolved into
a SIP URI. Call routing is based on the resulting SIP URI. Note
that the call routing step does not depend on the presence of an
E.164 number. Indeed, the resulting SIP URI may no longer even
Meyer Expires March 22, 2007 [Page 3]
Internet-Draft SPEERMINT Terminology September 2006
contain any numbers of any type. In particular, the SIP URI can be
advertised in various other ways, such as on a web page.
E.164 number <--- Peer Discovery
|
| <--- ENUM lookup of NAPTR in DNS
|
|
| ENUM Working Group Scope
=====+====================================================
| SPEERMINT Working Group Scope
|
SIP URI <--- Call Addressing Data (CAD)
|
|
| <--- 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
Note that in Figure 1, Call Addressing Data (CAD), is the data used
to route a call to the called domain's ingress point (see Section 3.3
for additional detail).
As illustrated in Figure 1, the ENUM Working Group is primarily
concerned with the acquisition of Call Addressing Data, or CAD, while
the SPEERMINT Working Group is focused on the use of such CAD in
routing session signaling requests. Importantly, the CAD can be
derived from ENUM (i.e., an E.164 DNS entry) or via any other
mechanism available to the user. Finally, note that the term "call"
is being used here in the most general sense, i.e., call routing and
session routing are used interchangeably.
Meyer Expires March 22, 2007 [Page 4]
Internet-Draft SPEERMINT Terminology September 2006
3. General Definitions
3.1. Signaling Path Border Element
A signaling path border element (SBE) provides signaling functions
such as protocol inter-working (for example, H.323 to SIP), identity
and topology hiding, and Call Admission Control (CAC) for a domain.
Such an SBE is frequently (but need not be) deployed on a domain's
border.
3.2. Data Path Border Element
A data path border element (DBE) provides media-related functions
such as deep packet inspection and modification, media relay, and
firewall support under SBE control. As was the case with the SBE, a
DBE is frequently deployed on a domain's border.
3.3. Call Addressing Data
Call Addressing Data, or CAD, is the data used to route a call 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 [RFC2782]
that resulted from the resolution of the CAD (i.e., a SIP URI).
More specifically, the CAD is the set of parameters that the outgoing
SBEs need to complete the call, and may include:
o A destination SIP URI
o A SIP proxy to send the INVITE to, including
* Fully Qualified Domain Name (FQDN)
* Port
* Transport Protocol (UDP/TCP/TLS)
o Security Parameters, including
* TLS certificate to use
* TLS certificate to expect
* TLS certificate verification setting
o Optional resource control parameters such as
Meyer Expires March 22, 2007 [Page 5]
Internet-Draft SPEERMINT Terminology September 2006
* Limits on the total number of calls to a peer
* Limits on SIP transactions/second
* Limits on the total amount of bandwidth used on a peering link
* In addition, lower layer parameters (such as DSCP markings on
SIP and/or media packets [RFC4594]) might also be included.
3.4. Call Routing
Call routing is the set of processes, rules, and CAD 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 CAD which are
used to route a real-time session to its termination point.
3.5. 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; various dial-plans (such as emergency
services dial-plans), however, may not directly use E.164 numbers.
3.6. IP Path
For purposes of this document, an IP path is defined to be a sequence
of zero or more IP router hops.
3.7. Peer Network
This document defines a peer network as the set of SIP UASs and SIP
UACs (customers) that are controlled by a single administrative
domain and can be reached via some IP path. Note that such a peer
network may also contain end-users who are located on the PSTN (and
hence may also be interconnected with the PSTN), as long as they are
also reachable via some IP path.
3.8. Service Provider
A Service Provider (or SP) is defined to be an entity that provides
layer 3 (IP) transport of SIP signaling and media packets.
3.9. Voice Service Provider
A Voice Service Provider (or VSP) is an entity that provides
transport of SIP signaling to its customers. In the event that the
Meyer Expires March 22, 2007 [Page 6]
Internet-Draft SPEERMINT Terminology September 2006
VSP is also an SP, it may also provide 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.
3.10. Internet Telephony Service Provider
An Internet Telephony Service Provider, or ITSP, is a synonym for
VSP. While the terms ITSP and VSP are frequently used
interchangeably, this document uses the term VSP.
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'
networks 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 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 4.2.1 and Section 4.2.2 below). Note that media streams
associated with this signaling (if any) are not constrained to follow
the same set of IP paths.
Meyer Expires March 22, 2007 [Page 7]
Internet-Draft SPEERMINT Terminology September 2006
4.2.1. Direct Peering
Direct peering describes those cases in which two service providers
interconnect without using an intervening layer 5 network.
4.2.2. Indirect Peering
Indirect, or 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 generally required that a trust relationship is
established between the originating service provider and the transit
network on one side, and the transit network and the termination
network on the other side.
4.2.3. Assisted Peering
In this case, some entity (usually a federation, see Section 5)
employs a central SIP proxy (which is not itself a VSP) to bridge
calls between participating networks.
5. Federations
A federation is a group of VSPs which agree to receive calls from
each other via SIP, and who agree on a set of administrative rules
for such calls (settlement, abuse-handling, ...) and the specific
rules for the technical details of the interconnection.
A federation may provide some or all of the following functionality:
* Common policies
+ Policy might be ad-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
Meyer Expires March 22, 2007 [Page 8]
Internet-Draft SPEERMINT Terminology September 2006
* 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. Acknowledgments
Many of the definitions were gleaned from detailed discussions on the
SPEERMINT, ENUM, and SIPPING mailing lists. Scott Brim, Mike Hammer,
Eli Katz, Gaurav Kulshreshtha, Otmar Lendl, Jason Livingood,
Alexander Mayrhofer, Jean-Francois Mule, Jonathan Rosenberg, David
Schwartz, Richard Shockey, Henry Sinnreich, Richard Stastny, Hannes
Tschofenig, 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.
7. 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.
8. IANA Considerations
This document creates no new requirements on IANA namespaces
[RFC2434].
9. Informative References
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
Meyer Expires March 22, 2007 [Page 9]
Internet-Draft SPEERMINT Terminology September 2006
specifying the location of services (DNS SRV)", RFC 2782,
February 2000.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[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.E164.2005]
International Telecommunications Union, "The International
Public Telecommunication Numbering Plan", ITU-
T Recommendation E.164, 02 2005.
[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.
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration
Guidelines for DiffServ Service Classes", RFC 4594,
August 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.
Author's Address
David Meyer
Email: dmm@1-4-5.net
Meyer Expires March 22, 2007 [Page 10]
Internet-Draft SPEERMINT Terminology September 2006
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.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Meyer Expires March 22, 2007 [Page 11]
