Network Working Group R. Santitoro
Internet Draft Nortel Networks
Document: draft-santitoro-rap-policy-appids-01.txt
Category: Informational R. Pabbati
Expiration: May 2001 Microsoft
November 2000
Standardized Application Identifiers for RSVP Identity Policy Element
draft-santitoro-rap-policy-appids-01.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 [1].
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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 [2].
1. Abstract
This draft proposes a standardized set of sub-application (SAPP)
identifiers for real-time application, namely, audio, video and telephony
(voice and fax) applications. These SAPP identifiers are used in the
RSVP Identity Policy Element in the Policy Data Object [RFC 2750]. The
standardized set of SAPP identifiers proposed in this draft facilitate
the deployment of policy-enabled, real-time applications.
2. Introduction
The Identity Policy Element (PE) is part of the Policy Data Object [RFC
2750] which may be included in RSVP [RFC 2205] signaling messages.
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Policy elements with a P-type of AUTH_APP are used to identify
applications and their attributes as defined in [RFC 2752].
The usage and format of the PE for application identification is defined
in [RFC 2753]. Policy Management Systems may use this application
identification information to apply appropriate policy decisions to
network elements under their control for different traffic flows.
Many types of real-time applications, such as IP telephony, video and
streaming audio, are difficult to classify. This is because they do not
use well-known, standardized port numbers or do not have standardized
protocol IDs. Furthermore, devices can send multiple types of traffic,
each requiring different treatment by the network so classifying only on
the source IP address is insufficient. SAPP can be used to distinguish
between these different traffic types by providing standardized names to
define the sub-application type. A Network Manager can use these
standardized SAPP identifiers to facilitate the creation and deployment
of application-based policies.
Finally, SAPP may be use in conjunction with other RSVP objects, e.g.,
Flowspec and Filterspec, to allow a policy server (PDP) to make more
informed policy decisions on the traffic to be sent to the network.
3. Standardized Set of Sub-Application IDs
RFC 2872 provides some examples for Sub-application (SAPP)
identification. These attributes are provided in the Policy Locator
attribute field in the Policy Element. To facilitate interoperability, a
standardized set of SAPP identifiers are provided in the next sections.
Many of the SAPP identifiers used are defined in [RTP Profile].
The sub-application (SAPP) identifiers described in the next sub-sections
consist of audio, voice, fax and video. Each of these has additional
SAPP identifiers that provide additional descriptors used to further
identify the application.
3.1. Audio
Audio SAPP identifiers must include one codec and may include one or more
additional SAPP identifiers. The focus of these audio SAPP identifiers
is for use in real-time, streaming audio applications such as Internet
radio or music broadcasts. However, these audio SAPP identifiers may
also be used for the identification of other audio applications.
SAPP=Audio
SAPP=MP1-32
SAPP=MP1-44.1
SAPP=MP1-48
SAPP=MP2-16
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SAPP=MP2-22.05
SAPP=MP2-24
SAPP=MP2-32
SAPP=MP2-44.1
SAPP=MP2-48
SAPP=MP3-32
SAPP=MP3-44.1
SAPP=MP3-48
This example specifies a 44.1Khz MP3 (MPEG-3) audio file playing on an
MP3 Player.
Example: APP=MP3 Player SAPP=Audio, SAPP=MP3-44.1
Voice SAPP identifiers must include at least one codec and may include
one or more additional SAPP identifiers. When a VAD (Voice Activity
Detection) SAPP, which includes silence suppression, is included, it
indicates that VAD is supported. If the VAD SAPP is not included then it
indicates that VAD is not supported.
While a voice application may be considered an audio application, this
document has separated them because there are unique differences between
the two. Voice applications are interactive and as such are more latency
sensitive than audio applications. A network administrator will apply
different policies that will take this into account and hence this
difference is of interest in the policy decisions made by the PDPs Policy
Decision Points) and PEP (Policy Enforcement Point) network elements
enforcing the traffic.
SAPP=Voice
SAPP=G.711
SAPP=G.729
SAPP=G.728
SAPP=G.722
SAPP=G.723.1
SAPP=G.726-40
SAPP=G.726-32
SAPP=G.726-24
SAPP=G.726-16
SAPP=GSM6.10
SAPP=GSM6.90
SAPP=GSM-HR
SAPP=GSM-EFR
SAPP=VAD
In this example, the IP Phone indicates that it will use the G.729 codec
with VAD (Voice Activity Detection) enabled (and hence, silence
suppression enabled) for a voice call.
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Example: APP=IP Phone, SAPP=Voice, SAPP=G.729, SAPP=VAD
There are two predominant ITU-T IP-based Fax standards, namely, T.38 and
T.37. The SAPP identifiers for fax must include the standard it is using
(T.38 or T.37) and at least one modulation scheme.
SAPP=Fax
SAPP=T.38
SAPP=T.37
SAPP=V.90
SAPP=V.34
SAPP=V.17
SAPP=V.29
SAPP=V.27
In this example, an IP Telephony (IPT) Gateway indicates that it will
initiate a T.38 real-time fax call using the V.17 (14.4kbps) modulation
scheme.
Example: APP=IPT Gateway, SAPP=Fax, SAPP=T.38, SAPP=V.17
3.4. Video
The following video picture format terminology is used in this section:
CIF: Common Intermediate Format. 352 x 288 pixels.
QCIF: Quarter CIF. 176 x 144 pixels.
SQCIF: Sub-QCIF. 128 x 96 pixels.
4CIF: 704 x 576 pixels.
16CIF: 1408 x 1152 pixels.
Video SAPP identifiers consist of the codec including the video window
size specified in the standard CIF (Common Intermediate Format) format.
This provides the PDP with more information on the type of video (window
size) to be sent over the network. A network administrator, for example,
may only allow an application to send H.263-QCIF video over expensive
wide area connections but allow H.263-CIF video over high bandwidth
campus LAN connections.
SAPP=Video
SAPP=H.261-CIF
SAPP=H.261-QCIF
SAPP=H.263-CIF
SAPP=H.263-QCIF
SAPP=H.263-SQCIF
SAPP=H.263-4CIF
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SAPP=H.263-16QCIF
SAPP=MPEG-1
SAPP=MPEG-2
This example represents a Quarter Common Intermediate Format (QCIF) frame
of H.261-encoded video to be played on a Media Player.
Example: APP=Media Player, SAPP=Video, SAPP=H.261-QCIF
4. Security Considerations
The identity policy element does not guarantee any association with the
application initiating it. However, the identity policy element can be
part of same RSVP message that contains the POLICY_DATA object [RFC 2750]
which can be used to authenticate users and applications.
5. References
[RFC 2753] Yavatkar R., et. al. "A Framework for Policy-based
Admission Control", RFC 2753, January 2000.
[RFC 2750] Herzog S., "RSVP Extensions for Policy Control", RFC
2750, January 2000.
[RFC 2752] Yadav S., et. al. "Identity Representation for RSVP", RFC
2752, January 2000.
[RFC 2872] Bernet Y., Pabbati R. "Application and Sub Application
Identity Policy Element for Use with RSVP", RFC 2872,
June 2000.
[COPS-RSVP] Herzog S., et. al. "COPS usage for RSVP", RFC 2749,
January 2000.
[RTP Profile] Schulzrinne H. and Casner S., "RTP Profile for Audio and
Video Conferences with Minimal Control", draft-ietf-avt-
profile-new-09.txt, July 2000.
[H.263] "Video Coding for Low Bitrate Communication", ITU
Recommendation H.263, 1996.
[H.261] "Video Codec for Audiovisual Services at p x 64 kbits/s",
ITU Recommendation H.261, 1993.
6. Acknowledgements
The authors would like to thank Yoram Bernet, Kwok-Ho Chan, Ron Pashby
and Eric Edwards for their input into the creation of this document.
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7. Author's Addresses
Ralph Santitoro
Nortel Networks
4100 Guardian Street
Simi Valley, CA 93063
Phone: 805-527-3024
Email: rsantito@nortelnetworks.com
Ramesh Pabbati
Microsoft
1 Microsoft Way
Redmond, WA 98054
Phone: 425-936-9438
Email: rameshpa@microsoft.com
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