| Rfc | 6406 |
|---|
| Title | Session PEERing for Multimedia INTerconnect (SPEERMINT)
Architecture |
|---|
| Author | D. Malas, Ed., J. Livingood, Ed. |
|---|
| Date | November 2011 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | INFORMATIONAL |
|---|
|
Internet Engineering Task Force (IETF) D. Malas, Ed.
Request for Comments: 6406 CableLabs
Category: Informational J. Livingood, Ed.
ISSN: 2070-1721 Comcast
November 2011
Session PEERing for Multimedia INTerconnect (SPEERMINT) Architecture
Abstract
This document defines a peering architecture for the Session
Initiation Protocol (SIP) and its functional components and
interfaces. It also describes the components and the steps necessary
to establish a session between two SIP Service Provider (SSP) peering
domains.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6406.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Contributions published or made publicly available before November
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material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
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it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction ....................................................3
2. New Terminology .................................................3
2.1. Session Border Controller (SBC) ............................3
2.2. Carrier-of-Record ..........................................4
3. Reference Architecture ..........................................4
4. Procedures of Inter-Domain SSP Session Establishment ............6
5. Relationships between Functions/Elements ........................7
6. Recommended SSP Procedures ......................................7
6.1. Originating or Indirect SSP Procedures .....................7
6.1.1. The Lookup Function (LUF) ...........................8
6.1.1.1. Target Address Analysis ....................8
6.1.1.2. ENUM Lookup ................................8
6.1.2. Location Routing Function (LRF) .....................9
6.1.2.1. DNS Resolution .............................9
6.1.2.2. Routing Table ..............................9
6.1.2.3. LRF to LRF Routing ........................10
6.1.3. The Signaling Path Border Element (SBE) ............10
6.1.3.1. Establishing a Trusted Relationship .......10
6.1.3.2. IPsec .....................................10
6.1.3.3. Co-Location ...............................11
6.1.3.4. Sending the SIP Request ...................11
6.2. Target SSP Procedures .....................................11
6.2.1. TLS ................................................11
6.2.2. Receive SIP Requests ...............................11
6.3. Data Path Border Element (DBE) ............................12
7. Address Space Considerations ...................................12
8. Acknowledgments ................................................12
9. Security Considerations ........................................12
10. Contributors ..................................................13
11. References ....................................................14
11.1. Normative References .....................................14
11.2. Informative References ...................................15
1. Introduction
This document defines a reference peering architecture for the
Session Initiation Protocol (SIP) [RFC3261], it's functional
components and interfaces in the context of session peering for
multimedia interconnects. In this process, we define the peering
reference architecture and its functional components, and peering
interface functions from the perspective of a SIP Service Provider's
(SSP's) [RFC5486] network. Thus, it also describes the components
and the steps necessary to establish a session between two SSP
peering domains.
An SSP may also be referred to as an Internet Telephony Service
Provider (ITSP). While the terms ITSP and SSP are frequently used
interchangeably, this document and other subsequent SIP peering-
related documents should use the term SSP. SSP more accurately
depicts the use of SIP as the underlying Layer 5 signaling protocol.
This architecture enables the interconnection of two SSPs in Layer 5
peering, as defined in the SIP-based session peering requirements
[RFC6271].
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 "Session Peering for
Multimedia Interconnect (SPEERMINT) Terminology" [RFC5486]. In
addition to normative references included herein, readers may also
find [RFC6405] informative.
2. New Terminology
[RFC5486] is a key reference for the majority of the SPEERMINT-
related terminology used in this document. However, some additional
new terms are used here as follows in this section.
2.1. Session Border Controller (SBC)
A Session Border Controller (SBC) is referred to in Section 5. An
SBC can contain a Signaling Function (SF), Signaling Path Border
Element (SBE) and Data Path Border Element (DBE), and may perform the
Lookup Function (LUF) and Location Routing Function (LRF), as
described in Section 3. Whether the SBC performs one or more of
these functions is, generally speaking, dependent upon how a SIP
Service Provider (SSP) configures such a network element. In
addition, requirements for an SBC can be found in [RFC5853].
2.2. Carrier-of-Record
A carrier-of-record, as used in Section 6.1.2.2, is defined in
[RFC5067]. That document describes the term as referring to the
entity having discretion over the domain and zone content and acting
as the registrant for a telephone number, as represented in ENUM.
This can be as follows:
o the service provider to which the E.164 number was allocated for
end user assignment, whether by the National Regulatory Authority
(NRA) or the International Telecommunication Union (ITU), for
instance, a code under "International Networks" (+882) or
"Universal Personal Telecommunications (UPT)" (+878), or
o if the number is ported, the service provider to which the number
was ported, or
o where numbers are assigned directly to end users, 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.
It is understood that the definition of "carrier-of-record" within a
given jurisdiction is subject to modification by national
authorities.
3. Reference Architecture
The following figure depicts the architecture and logical functions
that form peering between two SSPs.
For further details on the elements and functions described in this
figure, please refer to [RFC5486]. The following terms, which appear
in Figure 1 and are documented in [RFC5486], are reproduced here for
simplicity.
o Data Path Border Element (DBE): A data path border element (DBE)
is located on the administrative border of a domain through which
the media associated with an inter-domain session flows.
Typically, it provides media-related functions such as deep packet
inspection and modification, media relay, and firewall-traversal
support. The DBE may be controlled by the SBE.
o E.164 Number Mapping (ENUM): See [RFC6116].
o Fully Qualified Domain Name (FQDN): See [RFC1035].
o Location Routing Function (LRF): The Location Routing Function
(LRF) determines, for the target domain of a given request, the
location of the SF in that domain, and optionally develops other
Session Establishment Data (SED) required to route the request to
that domain. An example of the LRF may be applied to either
example in Section 4.3.3 of [RFC5486]. Once the ENUM response or
SIP 302 redirect is received with the destination's SIP URI, the
LRF must derive the destination peer's SF from the FQDN in the
domain portion of the URI. In some cases, some entity (usually a
third party or federation) provides peering assistance to the
Originating SSP by providing this function. The assisting entity
may provide information relating to direct (Section 4.2.1 of
[RFC5486]) or indirect (Section 4.2.2 of [RFC5486]) peering as
necessary.
o Lookup Function (LUF): The Lookup Function (LUF) determines, for a
given request, the target domain to which the request should be
routed. An example of an LUF is an ENUM [4] look-up or a SIP
INVITE request to a SIP proxy providing redirect responses for
peers. In some cases, some entity (usually a third party or
federation) provides peering assistance to the Originating SSP by
providing this function. The assisting entity may provide
information relating to direct (Section 4.2.1 of [RFC5486]) or
indirect (Section 4.2.2 of [RFC5486]) peering as necessary.
o Real-time Transport Protocol (RTP): See [RFC3550].
o Session Initiation Protocol (SIP): See [RFC3261].
o Signaling Path Border Element (SBE): A signaling path border
element (SBE) is located on the administrative border of a domain
through which inter-domain session-layer messages will flow.
Typically, it provides Signaling Functions such as protocol inter-
working (for example, H.323 to SIP), identity and topology hiding,
and Session Admission Control for a domain.
o Signaling Function (SF): The Signaling Function (SF) performs
routing of SIP requests for establishing and maintaining calls and
in order to assist in the discovery or exchange of parameters to
be used by the Media Function (MF). The SF is a capability of SIP
processing elements such as SIP proxies, SBEs, and User Agents.
o SIP Service Provider (SSP): A SIP Service Provider (SSP) is an
entity that provides session services utilizing SIP signaling to
its customers. In the event that the SSP is also a function of
the SP, it may also provide media streams to its customers. Such
an SSP may additionally be peered with other SSPs. An SSP may
also interconnect with the PSTN.
+=============++ ++=============+
|| ||
+-----------+ +-----------+
| SBE | +-----+ | SBE |
| +-----+ | SIP |Proxy| | +-----+ |
| | LUF |<-|------>|ENUM | | | LUF | |
| +-----+ | ENUM |TN DB| | +-----+ |
SIP | | +-----+ | |
------>| +-----+ | DNS +-----+ | +-----+ |
| | LRF |<-|------>|FQDN | | | LRF | |
| +-----+ | |IP | | +-----+ |
| +-----+ | SIP +-----+ | +-----+ |
| | SF |<-|----------------|->| SF | |
| +-----+ | | +-----+ |
+-----------+ +-----------+
|| ||
+-----------+ +-----------+
RTP | DBE | RTP | DBE |
------>| |--------------->| |
+-----------+ +-----------+
|| ||
SSP1 Network || || SSP2 Network
+=============++ ++=============+
Reference Architecture
Figure 1
4. Procedures of Inter-Domain SSP Session Establishment
This document assumes that in order for a session to be established
from a User Agent (UA) in the Originating (or Indirect) SSP's network
to a UA in the Target SSP's network the following steps are taken:
1. Determine the Target or Indirect SSP via the LUF. (Note: If the
target address represents an intra-SSP resource, the behavior is
out of scope with respect to this document.)
2. Determine the address of the SF of the Target SSP via the LRF.
3. Establish the session.
4. Exchange the media, which could include voice, video, text, etc.
5. End the session (BYE)
The Originating or Indirect SSP would perform steps 1-4, the Target
SSP would perform step 4, and either one can perform step 5.
In the case that the Target SSP changes, steps 1-4 would be repeated.
This is reflected in Figure 1, which shows the Target SSP with its
own peering functions.
5. Relationships between Functions/Elements
Please also refer to Figure 1.
o An SBE can contain a Signaling Function (SF).
o An SF can perform a Lookup Function (LUF) and Location Routing
Function (LRF).
o As an additional consideration, a Session Border Controller, can
contain an SF, SBE and DBE, and may act as both an LUF and LRF.
o The following functions may communicate as follows in an example
SSP network, depending upon various real-world implementations:
* SF may communicate with the LUF, LRF, SBE, and SF
* LUF may communicate with the SF and SBE
* LRF may communicate with the SF and SBE
6. Recommended SSP Procedures
This section describes the functions in more detail and provides some
recommendations on the role they would play in a SIP call in a Layer
5 peering scenario.
Some of the information in this section is taken from [RFC6271] and
is included here for continuity purposes. It is also important to
refer to Section 3.2 of [RFC6404], particularly with respect to the
use of IPsec and TLS.
6.1. Originating or Indirect SSP Procedures
This section describes the procedures of the Originating or indirect
SSP.
6.1.1. The Lookup Function (LUF)
The purpose of the LUF is to determine the SF of the target domain of
a given request and optionally to develop Session Establishment Data.
It is important to note that the LUF may utilize the public e164.arpa
ENUM root, as well as one or more private roots. When private roots
are used, specialized routing rules may be implemented; these rules
may vary depending upon whether an Originating or Indirect SSP is
querying the LUF.
6.1.1.1. Target Address Analysis
When the Originating (or Indirect) SSP receives a request to
communicate, it analyzes the target URI to determine whether the call
needs to be routed internally or externally to its network. The
analysis method is internal to the SSP; thus, outside the scope of
SPEERMINT.
If the target address does not represent a resource inside the
Originating (or Indirect) SSP's administrative domain or federation
of domains, then the Originating (or Indirect) SSP performs a Lookup
Function (LUF) to determine a target address, and then it resolves
the call routing data by using the Location Routing Function (LRF).
For example, if the request to communicate is for an im: or pres: URI
type [RFC3861] [RFC3953], the Originating (or Indirect) SSP follows
the procedures in [RFC3861]. If the highest priority supported URI
scheme is sip: or sips:, the Originating (or Indirect) SSP skips to
SIP DNS resolution in Section 5.1.3. Likewise, if the target address
is already a sip: or sips: URI in an external domain, the Originating
(or Indirect) SSP skips to SIP DNS resolution in Section 6.1.2.1.
This may be the case, to use one example, with
"sips:bob@biloxi.example.com".
If the target address corresponds to a specific E.164 address, the
SSP 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"; in the United
Kingdom, "00 1" could be converted to "+1". Once the SSP has an
E.164 address, it can use ENUM.
6.1.1.2. ENUM Lookup
If an external E.164 address is the target, the Originating (or
Indirect) SSP consults the public "User ENUM" rooted at e164.arpa,
according to the procedures described in [RFC6116]. The SSP must
query for the "E2U+sip" enumservice as described in [RFC3764], but
may check for other enumservices. The Originating (or Indirect) SSP
may consult a cache or alternate representation of the ENUM data
rather than actual DNS queries. Also, the SSP may skip actual DNS
queries if the Originating (or Indirect) SSP is sure that the target
address country code is not represented in e164.arpa.
If an im: or pres: URI is chosen based on an "E2U+im" [RFC3861] or
"E2U+pres" [RFC3953] enumserver, the SSP follows the procedures for
resolving these URIs to URIs for specific protocols such as SIP or
Extensible Messaging and Presence Protocol (XMPP) as described in the
previous section.
The Naming Authority Pointer (NAPTR) response to the ENUM lookup may
be a SIP address of record (AOR) (such as "sips:bob@example.com") or
SIP URI (such as "sips:bob@sbe1.biloxi.example.com"). In the case
when a SIP URI is returned, the Originating (or Indirect) SSP has
sufficient routing information to locate the Target SSP. In the case
of when a SIP AoR is returned, the SF then uses the LRF to determine
the URI for more explicitly locating the Target SSP.
6.1.2. Location Routing Function (LRF)
The LRF of an Originating (or Indirect) SSP analyzes target address
and target domain identified by the LUF, and discovers the next-hop
Signaling Function (SF) in a peering relationship. The resource to
determine the SF of the target domain might be provided by a third
party as in the assisted-peering case. The following sections define
mechanisms that may be used by the LRF. These are not in any
particular order and, importantly, not all of them have to be used.
6.1.2.1. DNS Resolution
The Originating (or Indirect) SSP uses the procedures in Section 4 of
[RFC3263] to determine how to contact the receiving SSP. To
summarize the [RFC3263] 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.
When communicating with another SSP, entities compliant to this
document should select a TLS-protected transport for communication
from the Originating (or Indirect) SSP to the receiving SSP if
available, as described further in Section 6.2.1.
6.1.2.2. Routing Table
If there are no End User ENUM records and the Originating (or
Indirect) SSP cannot discover the carrier-of-record or if the
Originating (or Indirect) SSP cannot reach the carrier-of-record via
SIP peering, the Originating (or Indirect) SSP may deliver the call
to the PSTN or reject it. Note that the Originating (or Indirect)
SSP may forward the call to another SSP for PSTN gateway termination
by prior arrangement using the local SIP proxy routing table.
If so, the Originating (or Indirect) SSP rewrites the Request-URI to
address the gateway resource in the Target SSP's domain and may
forward the request on to that SSP using the procedures described in
the remainder of these steps.
6.1.2.3. LRF to LRF Routing
Communications between the LRF of two interconnecting SSPs may use
DNS or statically provisioned IP addresses for reachability. Other
inputs to determine the path may be code-based routing, method-based
routing, time of day, least cost and/or source-based routing.
6.1.3. The Signaling Path Border Element (SBE)
The purpose of the Signaling Function is to perform routing of SIP
messages as well as 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 performs the
routing of SIP messages. The SBE may be a back-to-back user agent
(B2BUA) or it may act as a SIP proxy. Optionally, an SF may perform
additional functions such as Session Admission Control, SIP Denial-
of-Service protection, SIP Topology Hiding, SIP header normalization,
SIP security, privacy, and encryption. The SF of an SBE 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.
6.1.3.1. Establishing a Trusted Relationship
Depending on the security needs and trust relationships between SSPs,
different security mechanisms can be used to establish SIP calls.
These are discussed in the following subsections.
6.1.3.2. 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. However, such IPsec use should be
the subject of a future document as additional specification is
necessary to use IPsec properly and effectively.
6.1.3.3. Co-Location
In this scenario, the 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 SSPs could be sent
as clear text (unencrypted). However, even in these semi-trusted co-
location facilities, other security or access control mechanisms may
be appropriate, such as IP access control lists or other mechanisms.
6.1.3.4. Sending the SIP Request
Once a trust relationship between the peers is established, the
Originating (or Indirect) SSP sends the request.
6.2. Target SSP Procedures
This section describes the Target SSP Procedures.
6.2.1. TLS
The section defines the usage of TLS between two SSPs [RFC5246]
[RFC5746] [RFC5878]. When the receiving SSP receives a TLS client
hello, it responds with its certificate. The Target SSP certificate
should be valid and rooted in a well-known certificate authority.
The procedures to authenticate the SSP's originating domain are
specified in [RFC5922].
The SF of the Target SSP verifies that the Identity header is valid,
corresponds to the message, 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.
As noted above in Section 6.1.3.2, some deployments may utilize IPsec
rather than TLS.
6.2.2. Receive SIP Requests
Once a trust relationship is established, the Target SSP is prepared
to receive incoming SIP requests. For new requests (dialog forming
or not), the receiving SSP verifies if the target (Request-URI) is a
domain for which it is responsible. For these requests, there should
be no remaining Route header field values. For in-dialog requests,
the receiving SSP can verify that it corresponds to the top-most
Route header field value.
The receiving SSP may reject incoming requests due to local policy.
When a request is rejected because the Originating (or Indirect) SSP
is not authorized to peer, the receiving SSP should respond with a
403 response with the reason phrase "Unsupported Peer".
6.3. Data Path Border Element (DBE)
The purpose of the DBE [RFC5486] is to perform media-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 codec
(e.g., G.711) to another (e.g., EvRC). Additionally, the MF may
perform media relaying, media security [RFC3711], privacy, and
encryption.
7. Address Space Considerations
Peering must occur in a common IP address space, which is defined by
the federation, which may be entirely on the public Internet, or some
private address space [RFC1918]. The origination or termination
networks may or may not entirely be in the 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. Acknowledgments
The working group would like to thank John Elwell, Otmar Lendl, Rohan
Mahy, Alexander Mayrhofer, Jim McEachern, Jean-Francois Mule,
Jonathan Rosenberg, and Dan Wing for their valuable contributions to
various versions of this document.
9. Security Considerations
The level (or types) of security mechanisms implemented between
peering providers is, in practice, dependent upon on the underlying
physical security of SSP connections. This means, as noted in
Section 6.1.3.3, whether peering equipment is in a secure facility or
not may bear on other types of security mechanisms that may be
appropriate. Thus, if two SSPs peered across public Internet links,
they are likely to use IPsec or TLS since the link between the two
domains should be considered untrusted.
Many detailed and highly relevant security requirements for SPEERMINT
have been documented in Section 5 of [RFC6271]. As a result, that
document should be considered required reading.
Additional and important security considerations have been documented
separately in [RFC6404]. This document describes the many relevant
security threats to SPEERMINT, as well the relevant countermeasures
and security protections that are recommended to combat any potential
threats or other risks. This includes a wide range of detailed
threats in Section 2 of [RFC6404]. It also includes key requirements
in Section 3.1 of [RFC6404], such as the requirement for the LUF and
LRF to support mutual authentication for queries, among other
requirements which are related to [RFC6271]. Section 3.2 of
[RFC6404] explains how to meet these security requirements, and then
Section 4 explores a wide range of suggested countermeasures.
10. Contributors
Mike Hammer
Cisco Systems
Herndon, VA
US
EMail: mhammer@cisco.com
Hadriel Kaplan
Acme Packet
Burlington, MA
US
EMail: hkaplan@acmepacket.com
Sohel Khan, Ph.D.
Comcast Cable
Philadelphia, PA
US
EMail: sohel_khan@cable.comcast.com
Reinaldo Penno
Juniper Networks
Sunnyvale, CA
US
EMail: rpenno@juniper.net
David Schwartz
XConnect Global Networks
Jerusalem
Israel
EMail: dschwartz@xconnnect.net
Rich Shockey
Shockey Consulting
US
EMail: Richard@shockey.us
Adam Uzelac
Global Crossing
Rochester, NY
US
EMail: adam.uzelac@globalcrossing.com
11. References
11.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[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.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Protocol (SIP): Locating SIP Servers", RFC 3263,
June 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3764] Peterson, J., "enumservice registration for Session
Initiation Protocol (SIP) Addresses-of-Record", RFC 3764,
April 2004.
[RFC3861] Peterson, J., "Address Resolution for Instant Messaging
and Presence", RFC 3861, August 2004.
[RFC3953] Peterson, J., "Telephone Number Mapping (ENUM) Service
Registration for Presence Services", RFC 3953,
January 2005.
[RFC5067] Lind, S. and P. Pfautz, "Infrastructure ENUM
Requirements", RFC 5067, November 2007.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia
Interconnect (SPEERMINT) Terminology", RFC 5486,
March 2009.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, February 2010.
[RFC5853] Hautakorpi, J., Camarillo, G., Penfield, R., Hawrylyshen,
A., and M. Bhatia, "Requirements from Session Initiation
Protocol (SIP) Session Border Control (SBC) Deployments",
RFC 5853, April 2010.
[RFC5878] Brown, M. and R. Housley, "Transport Layer Security (TLS)
Authorization Extensions", RFC 5878, May 2010.
[RFC5922] Gurbani, V., Lawrence, S., and A. Jeffrey, "Domain
Certificates in the Session Initiation Protocol (SIP)",
RFC 5922, June 2010.
[RFC6116] Bradner, S., Conroy, L., and K. Fujiwara, "The E.164 to
Uniform Resource Identifiers (URI) Dynamic Delegation
Discovery System (DDDS) Application (ENUM)", RFC 6116,
March 2011.
[RFC6271] Mule, J-F., "Requirements for SIP-Based Session Peering",
RFC 6271, June 2011.
[RFC6404] Seedorf, J., Niccolini, S., Chen, E., and H. Scholz,
"Session PEERing for Multimedia INTerconnect (SPEERMINT)
Security Threats and Suggested Countermeasures", RFC 6404,
November 2011.
11.2. Informative References
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC6405] Uzelac, A., Ed. and Y. Lee, Ed., "Voice over IP (VoIP) SIP
Peering Use Cases", RFC 6405, November 2011.
Authors' Addresses
Daryl Malas (editor)
CableLabs
Louisville, CO
US
EMail: d.malas@cablelabs.com
Jason Livingood (editor)
Comcast
Philadelphia, PA
US
EMail: Jason_Livingood@cable.comcast.com