wdiff draft-ietf-speermint-architecture-04.txt draft-ietf-speermint-architecture-05.txt

Speermint Working Group R. Penno
Internet Draft Juniper Networks
Intended status: Informational D. Malas
Expires: January August 2008 Level 3
S. Khan
Comcast
A. Uzelac
Global Crossing
August 10, 2007
February 24, 2008

SPEERMINT Peering Architecture
draft-ietf-speermint-architecture-04
draft-ietf-speermint-architecture-05

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 January 2008.

Abstract

This document defines the SPEERMINT peering architecture, its
functional components and peering interface functions. It also
describes the steps taken to establish a session between two peering
domains in the context of the functions defined.

Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119[1] RFC 2119[1]

Table of Contents

1. Introduction...................................................3
2. Network Context................................................3 Context................................................4
3. Procedures.....................................................6 Procedures.....................................................5
4. Reference SPEERMINT Architecture...............................6
5. Peer Function Examples.........................................8
5.1. The Location Function (LF) of an Initiating Provider......8
5.1.1. Target address analysis..............................8
5.1.2. User ENUM Lookup.....................................9
5.1.3. Carrier ENUM lookup.................................10
5.1.4. Routing Table.......................................10
5.1.5. SIP DNS Resolution..................................10
5.1.6. SIP Redirect Server.................................11
5.2. The Location Function (LF) of a Receiving Provider.......11
5.2.1. Publish ENUM records................................11
5.2.2. Publish SIP DNS records.............................11
5.2.3. Subscribe Notify....................................11
5.3. Signaling Function (SF)..................................11
5.4. The Signaling Function (SF) of an Initiating Provider....12
5.4.1. Setup TLS connection................................12
5.4.2. IPSec...............................................12
5.4.3. Co-Location.........................................13 Co-Location.........................................12
5.4.4. Send the SIP request................................13 request................................12
5.5. The Signaling Function (SF) of an Initiating Provider....14
5.5.1. Verify TLS connection...............................14
5.5.2. Receive SIP requests................................14
5.6. Media Function (MF)......................................15
5.7. Policy Considerations....................................15
6. Call Control and Media Control Deployment Options.............16
7. Address space considerations..................................18 considerations..................................17
8. Security Considerations.......................................18 Considerations.......................................17
9. IANA Considerations...........................................18
10. Acknowledgments..............................................18
11. References...................................................19
11.1. Normative References....................................19
11.2. Informative References..................................20
Author's Addresses...............................................21
Intellectual Property Statement..................................21
Disclaimer of Validity...........................................22

1. Introduction

The objective of this document is to define a reference peering
architecture in the context of Session PEERing for Multimedia
INTerconnect (SPEERMINT). In this process, we define the peering
reference architecture (reference, for short), it's functional
components, and peering interface functions from the perspective of
a
real-time communications (Voice and Multimedia) IP SIP [3] Service provider provider's (SSP) network.

This architecture allows the interconnection of two service providers SSPs in layer 5
peering as defined in the SPEERMINT Requirements [13] and
Terminology [12] documents for the purpose SIP-based voice and
multimedia traffic. documents.

Layer 3 peering is outside the scope of this document. Hence, the
figures in this document do not show routers so that the focus is on
Layer 5 protocol aspects.

This document uses terminology defined in the SPEERMINT Terminology
document [12]. [12], so the reader should be familiar with all the terms
defined there.

2. Network Context

Figure 1 shows an example network context. Two SIP providers SSPs can form a Layer
5 peer peering over either the public Internet or private Layer 3 Layer3
networks. In addition, two or more providers may form a SIP (Layer
5) federation [17] [13] on either the public Internet or private Layer 3
networks. This document does not make any assumption whether the SIP
providers directly peer to each other or through Layer 3 transit
network as per use case of [16].

Note that Figure 1 allows for the following potential SPEERMINT
peering scenarios:

o Enterprise to Enterprise across the public Internet

o Enterprise to Service Provider SSP across the public Internet

o Service Provider SSP to Service Provider SSP across the public Internet

o Enterprise to enterprise across a private Layer 3 network

o Enterprise to Service Provider SSP across a private Layer 3 network

o Service Provider SSP to Service Provider SSP across a private Layer 3 network

The members of a federation may jointly use a set of functions such
as location peering function, application signaling function, subscriber
database media function, ENUM
database or SIP Registrar, SIP proxies, and/or functions that
synthesize various SIP and non-SIP based applications. Similarly,
two providers SSPs may jointly use a set of peering functions. The federation functions
or the peering functions can be
either public or private.

+-------------------+
| |
| Public |
| Peering Function |
| or Function |
| Public |
|Federation Function|
+-------------------+
|
-----
+-----------+ / \ +-----------+
|Enterprise | -- -- |Enterprise |
|Provider A |-----------/ \-----------|Provider B |
+-----------+ -- -- +-----------+
/ Public \
| Internet |
\ (Layer 3) /
+-----------+ -- -- +-----------+
|Service |-----------\ /-----------|Service |
|Provider C | -- -- |Provider D |
+-----------+ \_____/ +-----------+
| Layer 3 Peering
| Point (out of scope)
-----
+-----------+ / \ +-----------+
|Enterprise | -- -- |Enterprise |
|Provider E |-----------/ \-----------|Provider F |
+-----------+ -- Service Private -- +-----------+
/ Provider Network \
| Private (Layer 3) |
\ Network /
+-----------+ -- (Layer 3) -- +-----------+
|Service |-----------\ /-----------|Service
|
|Provider SSP G |-----------\ /-----------| SSP H |
| | -- -- |Provider H | |
+-----------+ \____/ +-----------+
|
+-------------------+
| Private |
| SIP |
| Peering Function |
| or |
|Federation Function|
+-------------------+

Figure 1: SPEERMINT Network Context

3. Procedures

This document assumes that a call from an a UAC end user in the
initiating
peer peer's network goes through the following steps to
establish a call to an end
user a UAS in the receiving peer: peer's network:

1. The analysis of a target address.

a. If the target address represents an intra-VSP intra-SSP resource,
we go directly to step 4.

2. the discovery of the receiving peering point address,

3. the enforcement of authentication and potentially other policy,
policies,

4. the discovery of end user address, the UAS,

5. the routing of SIP messages,

6. the session establishment,

7. the transfer of media, media which could include voice, video, text
and others,

8. and the session termination.

4. Reference SPEERMINT Architecture

Figure 2 depicts the SPEERMINT architecture and logical functions
that form the peering between two SIP service providers. SSPs.

+------+
| DNS, |
+---------|
+---------->| Db, |---------+ |<---------+
| | etc | |
| +------+ |
| |
--------------- ---------------
------|-------- -------|-------
/ v \ / v \
| +--LUF-+ | | +--LUF-+ |
| | | | | +------+ | | +------+ |
| | DNS, | | | | DNS, | |
| | Db, | | | | Db, | |
| | etc | | | | etc | |
| +------+ | | +------+ |
| | | | | |
| | | +---SF--+ +---SF--+ | | | |
| v | | v |
| SBE | | SBE +--LRF-+ | | +--LRF-+ | Originating
| | | | Terminating | | +---SF--+ +---SF--+ | | Domain
| | Domain | | +---MF--+ +---MF--+ | | SSP | |
| | SSP | | | DBE | | DBE |
| +------+ | | +------+ |
| \ | | / | +---MF--+ +---MF--+
| `. | | / |
| \ | +----LF---+ +----LF---+ | .' | +-LF--|----+
| `. +---SF--+ +---SF--+ / | +----|--LS-+
| \| | | | / |
| | SBE | | SBE | |
| Originating | SM | | LS | Target | LS
| +---SF--+ +---SF--+ | SM
| SSP | | SSP |
| +---MF--+ +---MF--+ |
| | | | | |
| | +----|----+ +----|----+ DBE | | DBE | +----------+| |+----------+ |
| | | | | |
| +---MF--+ +---MF--+ |
\ / \ /
--------------- ---------------
Figure 2: Reference SPEERMINT Architecture

The procedures presented in Chapter 3 are implemented by a set of
peering functions:

o Location

The Look-Up Function (LF): Purpose is (LUF) provides a mechanism for determining for
a given request the target domain to develop Session
Establishment Data (SED) by discovering which the Signaling request should be
routed.

The Location Routing Function
(SF) and (LRF) determines for the end user's reachable host (IP address target domain
of a given request the location of the SF in that domain and port).
optionally develops other SED required to route the request to that
domain.

Location Function (LF): The
location function Location functions is distributed across composed of the Location Server (LS)
LUF and Session Manager (SM).

o LRF functions

Signaling Function (SF): Purpose is to perform SIP call routing, to
optionally perform termination and re-initiation of call, to
optionally implement security and policies on SIP messages, and to
assist in discovery/exchange of parameters to be used by the Media
Function (MF). The signaling function is located within the
Signaling Path Border Element (SBE)

Media Function (MF): Purpose is to perform media related function
such as media transcoding and media security implementation between
two SIP providers.

The media function is located within
the Data Path Border Element (DBE).

The intention of defining these functions is to provide a framework
for design segmentation and allow each one to evolve separately. independently.

5. Peer Function Examples

This section describes the peering functions in more detail and provides
some examples on the role they would play in a SIP call in a Layer 5
peering scenario.

Some of the information in the chapter is taken from [14]. [14] and is put
here for continuity purposes.

5.1. The Location Function (LF) of an Initiating Provider

Purpose is to determine the SF of the target domain of a given
request and optionally develop Session Establishment Data (SED) [12] by
discovering the Signaling Function (SF), and end user's reachable
host (IP address and host).
[12]. The LF of an Initiating provider SSP analyzes target address and
discovers the next hop signaling function (SF) in a peering
relationship using DNS, SIP Redirect Server, or the Look-Up Function. The resource to determine
the SF of the target domain might be provided by a
functional equivalent database. third-party as in
the assisted-peering case.

5.1.1. Target address analysis
When the initiating provider SSP receives a request to communicate, the
initiating provider it
analyzes the target state data to determine whether the call needs
to be terminated internal or external to its network. The analysis
method is internal to the provider's policy; SSP; thus, outside the scope of SPEERMINT.
Note that the peer SSP is free to consult any manner of private data
sources to make this determination.

If the target address does not represent a resource inside the
initiating peer's SSP's administrative domain or federation of domains, the
initiating provider SSP resolves the call routing data by using the Location
Function (LF). Examples of the LF are the functions of ENUM,
Routing Table, SIP DNS, and SIP Redirect Server.

If the request to communicate is for an im: or pres: URI type, the
initiating peer follows the procedures in [8]. If the highest
priority supported URI scheme is sip: or sips:, the initiating peer
skips to SIP DNS resolution in Section 5.1.5. Likewise, if the
target address is already a sip: or sips: URI in an external domain,
the initiating peer skips to SIP DNS resolution in Section 5.1.5.

If the target address corresponds to a specific E.164 address, the
peer may need to perform some form of number plan mapping according
to local policy. For example, in the United States, a dial string
beginning "011 44" could be converted to "+44", or in the United
Kingdom "00 1" could be converted to "+1". Once the peer has an
E.164 address, it can use ENUM.

5.1.2. User ENUM Lookup

If an external E.164 address is the target, the initiating peer
consults the public "User ENUM" rooted at e164.arpa, according to
the procedures described in RFC 3761. The peer MUST query for the
"E2U+sip" enumservice as described in RFC 3764 [11], but MAY check
for other enumservices. The initiating peer MAY consult a cache or
alternate representation of the ENUM data rather than actual DNS
queries. Also, the peer MAY skip actual DNS queries if the
initiating peer is sure that the target address country code is not
represented in e164.arpa. If a sip: or sips: URI is chosen the peer
skips to Section 5.1.5.

If an im: or pres: URI is chosen for based on an "E2U+im" [10] or
"E2U+pres" [9] enumserver, the peer follows the procedures for
resolving these URIs to URIs for specific protocols such a SIP or
XMPP as described in the previous section.

5.1.3. Carrier Infrastructure ENUM lookup

Next the initiating peer checks for a carrier-of-record in a carrier
ENUM domain according to the procedures described in [12]. As in
the previous step, the peer MAY consult a cache or alternate
representation of the ENUM data in lieu of actual DNS queries. The
peer first checks for records for the "E2U+sip" enumservice, then
for the "E2U+pstn" enumservice as defined in [21]. If a terminal
record is found with a sip: or sips: URI, the peer skips to Section
5.1.5, otherwise the peer continues processing according to the next
section.

5.1.4. Routing Table

If there is no user ENUM records and the initiating peer cannot
discover the carrier-of-record or if the initiating peer cannot
reach the carrier-of-record via SIP peering, the initiating peer
still needs to deliver the call to the PSTN or reject the call. it. Note that
the initiating peer MAY still sends forward the call to another provider SSP for
PSTN gateway termination by prior arrangement using a the routing
table.

If so, the initiating peer rewrites the Request-URI to address the
gateway resource in the target provider's SSP's domain and MAY forward the
request on to that provider SSP using the procedures described in the
remainder of these steps.

5.1.5. SIP DNS Resolution

Once a sip: or sips: in an external domain is selected as the
target, the initiating peer MAY apply local policy to decide whether
forwarding requests to the target domain is acceptable. If so, the
initiating peer uses the procedures in RFC 3263 [6] [4] Section 4 to
determine how to contact the receiving peer. To summarize the RFC
3263 procedure: unless these are explicitly encoded in the target
URI, a transport is chosen using NAPTR records, a port is chosen
using SRV records, and an address is chosen using A or AAAA records.
Note that these are queries of records in the global DNS.

When communicating with a public external peer, entities compliant
to this document MUST only select a TLS-protected transport for
communication from the initiating peer to the receiving peer. Note
that this is a single-hop requirement. Either peer MAY insist on
using a sips: URI which asserts that each hop is TLS-protected, but
this document does not require protection over each hop.

5.1.6. SIP Redirect Server

A SIP Redirect Server may help in resolving the current address of a
mobile target address.
UAS.

5.2. The Location Function (LF) of a Receiving Provider

5.2.1. Publish ENUM records

The receiving peer SHOULD participate by publishing "E2U+sip" and
"E2U+pstn" records with sip: or sips: URIs wherever a public carrier
ENUM root is available. This assumes that the receiving peer wants
to peer by default. Even when When the receiving peer does not want to accept
traffic from specific initiating peers, it MAY still reject requests
on a case-by-case call-by-call basis.

5.2.2. Publish SIP DNS records

To receive peer requests, the receiving peer MUST insure that it
publishes appropriate NAPTR, SRV, and address (A and/or AAAA)
records in the global DNS that resolve an appropriate transport, port, and
address to a LF relevant SIP server. to the peer's SF.

5.2.3. Subscribe Notify

Policy

Policies function may also be optionally implemented by dynamic
subscribe, notify, and exchange of policy information and feature
information among providers SSPs [22].

5.3. Signaling Function (SF)

The purpose of signaling function is to perform routing of SIP
messages, to optionally perform termination and re-initiation of a
call, to optionally implement security and policies on SIP messages,
and to assist in discovery/exchange of parameters to be used by the
Media Function (MF).

The signaling function perform the routing of SIP messages are performed by SIP proxies. messages. The
optional termination and re-initiation of calls are performed by
B2BUA. the
signaling path border element (SBE).

Optionally, a SF may perform additional functions such as Session
Admission Control, SIP Denial of Service protection, SIP Topology
Hiding, SIP header normalization, and SIP security, privacy and
encryption.

The signaling function SF can also process SDP payloads for media information such as
media type, bandwidth, and type of codec; then, communicate this
information to the media function. Signaling function may optionally
communicate with the network layer to pass Layer 3 related policies [10]

5.4. The Signaling Function (SF) of an Initiating Provider

5.4.1. Setup TLS connection

Once a transport, port, and address are found, the initiating peer SSP
will open or find a reusable TLS connection to the peer. The
initiating provider MUST verify the server certificate which that SHOULD
be rooted in a well-known certificate authority. The initiating
provider SSP
MUST be prepared to provide a TLS client certificate upon request
during the TLS handshake. The client certificate MUST contain a DNS
or URI choice type in the subjectAltName which corresponds to the
domain asserted in the host production of the From header URI. The
certificate SHOULD be valid and rooted in a well-
known well-known certificate
authority.

Note that the client certificate MAY contain a list of entries in
the subjectAltName, only one of which has to match the domain in the
From header URI.

5.4.2. IPSec

In certain deployments the use of IPSec between the signaling
functions of the originating and terminating domains can be used as
a security mechanism instead of TLS.

5.4.3. Co-Location

In this scenario the signaling functions SFs are co-located in a
physically secure location and/or are members of a segregated
network. In this case messages between the originating and
terminating domains SSPs would be sent as clear text.

5.4.4. Send the SIP request

Once a TLS connection between the peers is established, the
initiating peer sends the request. When sending some requests, the
initiating peer MUST verify and assert the senders identity using
the SIP Identity mechanism.

The domain name in the URI of the From: header MUST be a domain
which was present in the certificate presented provided when establishing the
TLS connection for this request, even if the user part has an
anonymous value. If the From header contains the user URI parameter
with the value of "phone", the user part of the From header URI MUST
be a complete and valid tel: URI [9] telephone-subscriber
production, and SHOULD be a global-number. For example, the
following are all
acceptable, acceptable and the first three are encouraged:

From: "John Doe" <john.doe@example.net> john.doe@example.net

From: "+12125551212" <+12125551212@example.net;user=phone>

From: "Anonymous" <anonymous@example.net>

From: <4092;phone-context=+12125554000@example.net;user=phone>

From: "5551212" <5551212@example.net>

The following are not acceptable:

From: "2125551212" <2125551212@example.net;user=phone>

From: "Anonymous" <anonymous@anonymous.invalid>

In addition, for new dialog-forming requests and non-dialog-forming
requests, the request MUST contain a valid Identity and
Identity-Info header as described in [12]. The Identity-Info header
must present a domain name which that is represented in the certificate presented
provided when establishing the TLS connection over which the request
is sent. The initiating peer SHOULD include an Identity header on
in-dialog requests as well, if the From header field value matches
an identity the initiating peer is willing to assert.

The initiating peer MAY include any SIP option-tags in Supported,
Require, or Proxy-Require headers according to procedures in
standards-track SIP extensions. Note however that the initiating
peer MUST be prepared to fallback to baseline SIP functionality as
defined by the mandatory-to-implement features of RFC 3261, RFC 3263,
and
3263,and RFC 3264 [7], except that peers implementing this
specification MUST implement SIP over TLS using the sip: URI scheme,
the SIP Identity header, and RFC 4320 [10] non-INVITE transaction
fixes.

5.5. The Signaling Function (SF) of an Initiating Target Provider

5.5.1. Verify TLS connection

When the receiving peer receives a TLS client hello, it responds
with its certificate. The receiving peer certificate SHOULD be
valid and rooted in a well-known certificate authority. The
receiving peer MUST request and verify the client certificate during
the TLS handshake.

Once the initiating peer has been authenticated, the receiving peer
can authorize communication from this peer based on the domain name
of the peer and the root of its certificate. This allows two
authorization models to be used, together or separately. In the
domain-based model, the receiving peer can allow communication from
peers with some trusted administrative domains which that use general-
purpose certificate authorities, without explicitly permitting all
domains with certificates rooted in the same authority. It also
allows a certificate authority (CA) based model where every domain
with a valid certificate rooted in some list of CAs is automatically
authorized.

5.5.2. Receive SIP requests

Once a TLS connection is established, the receiving peer is prepared
to receive incoming SIP requests. For new dialog-forming requests
and out-of-dialog requests, (dialog forming
or not) the receiving peer verifies that the target (request-URI) is
a domain which that for which it is responsible.
(For For these requests, there
should be no remaining Route header field
values.) values. Next the receiving
verifies that the Identity header is valid, corresponds to the
message, and corresponds to the Identity-Info header, and that the
domain in the From header corresponds to one of the domains in the
TLS client certificate.

For in-dialog requests, the receiving peer can verify that it
corresponds to the top-most Route header field value. The peer also
validates any Identity header if present.

The receiving peer MAY reject incoming requests due to local policy.
When a request is rejected because the initiating peer is not
authorized to peer, the receiving peer SHOULD respond with a 403
response with the reason phrase "Unsupported Peer".

5.6. Media Function (MF)

Examples

The purpose of the MF is to perform media function related functions such as
media transcoding and media security implementation between two
SSPs.

An Example of this is to transform a voice payload from one
coding codec
(e.g., G.711) to another (e.g., EvRC), EvRC). Additionally, the MF MAY
perform media relaying, media security, privacy, and encryption.

Editor's Note: This section will be further updated.

5.7. Policy Considerations

In the context of the SPEERMINT working group when two Layer 5
devices (e.g., SIP Proxies) SSPs peer,
there is MAY be a need desire to exchange peering policy information. information
dynamically. There are specifications in progress in the SIPPING
working group to define policy exchange between an UA and a domain
[23] and providing profile data to SIP user agents [24] These
considerations borrow from both.

Following the terminology introduced in [12], this package uses the
terms Peering Session-Independent and Session-Specific policies in
the following context.

o Peering Session-Independent policies include Diffserv Marking,
Policing, Session Admission Control, and domain reachabilities,
amongst others. The time period between Peering Session-
Independent policy changes is much greater than the time it
takes to establish a call.

o Peering Session-Specific polices includes supported
connection/call rate, total number of connections/calls
available, current utilization, amongst others. Peering
Session-specific policies can change within the time it takes
to establish a call.

These policies can be Peer dependent or independent, creating the
following peering policy tree definition:

o Peer Independent
Session dependent
Session independent
o Peer Dependent
Session dependent
Session independent

6. Call Control and Media Control Deployment Options

The peering functions can either be deployed along the following two
dimensions depending upon how the signaling function and the media
function along with IP functions are implemented:

Composed or Decomposed: Addresses the question whether the media
paths
must flow through the same physical and geographic nodes elements as the
call signaling, SIP
dialogs and sessions.

Centralized or Distributed: Addresses the question whether the
logical and physical peering points are in one geographical location
or distributed to multiple physical locations on the service provider SSP's network.

In a composed model, SF and MF functions are implemented in one
peering logical element.

Provider A Provider B
---------- . . ----------
/ \ . . / \
| | . _ . | |
| +----+ . / \_ . +----+ |
| | SF |<-----/ \------| SF | |
| +-+--+ . /Transit\ . | | |
| | | . / IP \ . | | |
| +-+--+ . \ Provider| . | | |
| | MF |<~~~~\(Option)|~~~~| MF | |
| +----+ . \ / . +----+ |
| | . \__ _/ . | |
\_________ / . . \________ _/
---------- ----------

--- Signal (SIP)
~~~ Bearer (RTP/IP)
... Scope of peering

Figure 3: Decomposed v. Collapsed Peering

The advantage of a collapsed peering architecture is that one-element one-
element solves all peering issues. Disadvantage examples of this
architecture are single point of failure, bottle neck, bottleneck, and complex
scalability.

In a decomposed model, SF and MF are implemented in separate peering
logical elements. Signaling functions SFs are implemented in a proxy and
media functions MFs are
implemented in another logical element. The scaling of signaling
versus scaling of media may differ between applications.
Decomposing allows each to follow a separate migration path.

This model allows the implementation of M:N model where one SF is
associated with multiple peering MF and one peering MF is associated
with multiple peering proxies. Generally, a vertical protocol
associates the relationship between a SF and a MF. This architecture
reduces the potential of a single point of failure. This architecture, It allows
separation of the policy decision point and the policy enforcement
point. An example of disadvantages is the scaling complexity because
of the M:N relationship and latency due to the vertical control
messages between entities.

7. Address space considerations

Peering must occur in a common address space, which is defined by
the federation, which may be entirely on the public Internet, or
some private address space. The origination or termination networks
may or may not entirely be in that same address space. If they are
not, then a network address translation (NAT) or similar may be
needed before the signaling or media is presented correctly to the
federation. The only requirement is that all associated entities
across the peering interface are reachable.

8. Security Considerations

In all cases, cryptographic-based security should be maintained as
an optional requirement between peering providers conditioned on the
presence or absence of underlying physical security of peer
connections, e.g. within the same secure physical building.

In order to maintain a consistent approach, unique and specialized
security requirements common for the majority of peering
relationships, should be standardized within the IETF. These
standardized methods may enable capabilities such as dynamic peering
relationships across publicly maintained interconnections.

TODO: Address RFC-3552 BCP items.

9. IANA Considerations

There are no IANA considerations at this time.

10. Acknowledgments

The working group thanks Sohel Khan for his initial architecture
draft that helped to initiate work on this draft.

A significant portion of this draft is taken from [14] with
permission from the author R. Mahy. The other important contributor
is Otmar Lendl.

11. References

11.1. Normative References

[1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[2] Mealling, M. and R. Daniel, "The Naming Authority Pointer
(NAPTR) DNS Resource Record", RFC 2915, September 2000.

[3] 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.

[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol
(SIP): Locating SIP Servers", RFC 3263, June 2002.

[5] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and
T. Wright, "Transport Layer Security (TLS) Extensions", RFC
4366, April 2006.

[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications", STD
64, RFC 3550, July 2003.

[7] Peterson, J., Liu, H., Yu, J., and B. Campbell, "Using E.164
numbers with the Session Initiation Protocol (SIP)", RFC 3824,
June 2004.

[8] Peterson, J., "Address Resolution for Instant Messaging and
Presence",RFC 3861, August 2004.

[9] Peterson, J., "Telephone Number Mapping (ENUM) Service
Registration for Presence Services", RFC 3953, January 2005.

[10] ETSI TS 102 333: " Telecommunications and Internet converged
Services and Protocols for Advanced Networking (TISPAN); Gate
control protocol".

[11] Peterson, J., "enumservice registration for Session Initiation
Protocol (SIP) Addresses-of-Record", RFC 3764, April 2004.

[12] Livingood, J. and R. Shockey, "IANA Registration for an
Enumservice Containing PSTN Signaling Information", RFC 4769,
November 2006.

11.2. Informative References

[13] Meyer, Malas, D., "SPEERMINT Terminology", draft-ietf-speermint-
terminology-08
terminology-16 (work in progress), Junly 2007. February 2008.

[14] Mule, J-F., "SPEERMINT Requirements for SIP-based VoIP
Interconnection", draft-ietf-speermint-requirements-02.txt,
July draft-ietf-speermint-requirements-03.txt,
November 2007.

[15] Mahy, R., "A Minimalist Approach to Direct Peering", draft-
mahy-speermint-direct-peering-02.txt, July 2007.

[16] Penno, R., et al., "SPEERMINT Routing Architecture Message
Flows", draft-ietf-speermint-flows-02.txt", April 2007.

[17] Lee, Y., "Session Peering Use Case for Cable", draft-lee-
speermint-use-case-cable-01.txt, June, 2006.

[18] Houri, A., et al., "RTC Provisioning Requirements", draft-
houri-speermint-rtc-provisioning-reqs-00.txt, June, 2006.

[19]

[18] Habler, M., et al., "A Federation based VOIP Peering
Architecture", draft-lendl-speermint-federations-03.txt,
September 2006.

[20]

[19] Mahy, R., "A Telephone Number Mapping (ENUM) Service
Registration for Instant Messaging (IM) Services", draft-ietf-
enum-im-service-03 (work in progress), March 2006.

[21] RFC 5028

[20] Haberler, M. and R. Stastny, "Combined User and Carrier ENUM
in the e164.arpa tree", draft-haberler-carrier-enum-03 (work
in progress), March 2006.

[22]

[21] Penno, R., Malas D., and Melampy, P., "A Session Initiation
Protocol (SIP) Event package for Peering", draft-penno-sipping-
peering-package-00 draft-penno-
sipping-peering-package-01 (work in progress), September 2006.

[23]

[22] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML",
W3C REC REC-xml-names-19990114, January 1999.

[24]

[23] Burger, E (Ed.), "A Mechanism for Content Indirection in
Session Initiation Protocol (SIP) Messages", RFC 4483, May
2006

Author's Addresses

Mike Hammer
Cisco Systems
13615 Dulles Technology Drive
Herndon, VA 20171
USA
Email: mhammer@cisco.com

Sohel Khan, Ph.D.
Comcast Cable Communications
U.S.A
Email: sohel_khan@cable.comcast.com

Daryl Malas
Level 3 Communications LLC
1025 Eldorado Blvd.
Broomfield, CO 80021
USA
EMail: daryl.malas@level3.com

Reinaldo Penno (Editor)
Juniper Networks
1194 N Mathilda Avenue
Sunnyvale, CA
USA
Email: rpenno@juniper.net

Adam Uzelac
Global Crossing
1120 Pittsford Victor Road
PITTSFORD, NY 14534
USA
Email: adam.uzelac@globalcrossing.com

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.

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.

Disclaimer of Validity

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, THE
IETF TRUST 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.

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.

Acknowledgment

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