draft-ietf-avt-rtp-interop-01.txt   draft-ietf-avt-rtp-interop-02.txt 
Colin Perkins Colin Perkins
University College London University College London
RTP Interoperability Statement RTP Interoperability Statement
draft-ietf-avt-rtp-interop-02.txt
draft-ietf-avt-rtp-interop-01.txt
Status of this memo Status of this memo
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Abstract Abstract
It is required to demonstrate interoperability of RTP implementations It is required to demonstrate interoperability of RTP implementations
in order to move the RTP specification to draft standard. This memo in order to move the RTP specification to draft standard. This memo
outlines those features to be tested, as the first stage of an outlines those features to be tested, as the first stage of an
interoperability statement. interoperability statement.
1 Introduction 1 Introduction
The Internet standards process [1] places a number of requirements The Internet standards process [1] places a number of requirements
on a standards track protocol specification. In particular, when on a standards track protocol specification. In particular, when
advancing a protocol from proposed standard to draft standard it advancing a protocol from proposed standard to draft standard it
is necessary to demonstrate at least two independent and interoperable is necessary to demonstrate at least two independent and interoperable
implementations, from different code bases, of all options and features implementations, from different code bases, of all options and features
of that protocol. Further, in cases where one or more options or of that protocol. Further, in cases where one or more options or
features have not been demonstrated in at least two interoperable features have not been demonstrated in at least two interoperable
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implementations, the specification may advance to the draft standard implementations, the specification may advance to the draft standard
level only if those options or features are removed. The Real-time level only if those options or features are removed. The Real-time
Transport Protocol, RTP, was originally specified in RFC1889 as a Transport Protocol, RTP, was originally specified in RFC1889 as a
proposed standard [2]. The revision of this specification for draft proposed standard [2]. The revision of this specification for draft
standard status is well underway, so it has become necessary to conduct standard status is now well underway, so it has become necessary
such an interoperability demonstration. to conduct such an interoperability demonstration.
This memo describes the set of features and options of the RTP specification This memo describes the set of features and options of the RTP specification
which need to be tested as a basis for this demonstration. Due to the which need to be tested as a basis for this demonstration. Due to the
nature of RTP there are necessarily two types of test described: those nature of RTP there are necessarily two types of test described: those
which directly affect the interoperability of implementations at a ``bits which directly affect the interoperability of implementations at a ``bits
on the wire level'' and those which affect scalability and safety of the on the wire level'' and those which affect scalability and safety of the
protocol but do not directly affect interoperability. A related memo [4] protocol but do not directly affect interoperability. A related memo [4]
describes a testing framework which may aid with interoperability testing. describes a testing framework which may aid with interoperability testing.
This memo is for information only and does not specify a standard This memo is for information only and does not specify a standard
of any kind. of any kind.
2 Features and options required to demonstrate interoperability 2 Features and options required to demonstrate interoperability
In order to demonstrate interoperability it is required to produce In order to demonstrate interoperability it is required to produce
a statement of interoperability for each feature noted below. Such a statement of interoperability for each feature noted below. Such
a statement should note the pair of implementations tested, and a a statement should note the pair of implementations tested, including
pass/fail statement for each feature. It is not expected that every version numbers, and a pass/fail statement for each feature. It
implementation will implement every feature, but each feature needs is not expected that every implementation will implement every feature,
to be demonstrated by some pair of applications. but each feature needs to be demonstrated by some pair of applications.
Note that some of these tests depend on the particular profile used, Note that some of these tests depend on the particular profile used,
or upon options in that profile. For example, it will be necessary or upon options in that profile. For example, it will be necessary
to test audio and video applications operating under [3] separately. to test audio and video applications operating under [3] separately.
1. Interoperable exchange of data packets using the basic RTP header 1. Interoperable exchange of data packets using the basic RTP header
with no extension, padding or CSRC list. with no header extension, padding or CSRC list.
2. Interoperable exchange of data packets which use padding 2.Interoperable exchange of data packets which use padding.
3. Interoperable exchange of data packets which use a header extension. 3. Interoperable exchange of data packets which use a header extension.
There are three possibilities here: a) if both implementations There are three possibilities here: a) if both implementations
use a header extension in the same manner, it should be verified use a header extension in the same manner, it should be verified
that the receiver correctly receives the information contained that the receiver correctly receives the information contained
in the extension header; b) If the sender uses a header extension in the extension header; b) If the sender uses a header extension
and the receiver does not, it should be verified that the receiver and the receiver does not, it should be verified that the receiver
ignores the extension; c) If neither implementation implements ignores the extension; c) If neither implementation implements
an extended header, this test is considered a failure. an extended header, this test is considered a failure.
4. Interoperable exchange of data packets using the marker bit as 4. Interoperable exchange of data packets using the marker bit as
specified in the profile. specified in the profile.
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5. Interoperable exchange of data packets using the payload type 5. Interoperable exchange of data packets using the payload type
field to differentiate multiple payload formats according to field to differentiate multiple payload formats according to
a profile definition. a profile definition.
6. Interoperable exchange of data packets containing a CSRC list 6.Interoperable exchange of data packets containing a CSRC list.
7. Interoperable exchange of RTCP packets, which must be compound 7. Interoperable exchange of RTCP packets, which must be compound
packets containing at least an initial SR or RR packet and an packets containing at least an initial SR or RR packet and an
SDES CNAME packet. SDES CNAME packet. Other RTCP packet types may be included,
but this is not required for this test.
8. Interoperable exchange of sender report packets when the receiver 8. Interoperable exchange of sender report packets when the receiver
of the sender reports is not also a sender (ie: sender reports of the sender reports is not also a sender (ie: sender reports
which only contain sender info, with no report blocks). which only contain sender info, with no report blocks).
9. Interoperable exchange of sender report packets when the receiver 9. Interoperable exchange of sender report packets when the receiver
of the sender reports is also a sender (ie: sender reports of the sender reports is also a sender (ie: sender reports which
which contain one or more report blocks). contain one or more report blocks).
10. Interoperable exchange of receiver report packets. 10. Interoperable exchange of receiver report packets.
11. Interoperable exchange of receiver report packets when not receiving 11. Interoperable exchange of receiver report packets when not receiving
data (ie: the empty receiver report which has to be sent first in each data (ie: the empty receiver report which has to be sent first
compound RTCP packet when no-participants are transmitting data). in each compound RTCP packet when no-participants are transmitting
data).
12. Interoperable choice of CNAME, according to the rules in the RTP 12.Interoperable and correct choice of CNAME, according to the rules
specification and profile. in the RTP specification and profile (applications using the
audio/video profile [3] under IPv4 should typically generate
a CNAME of the form `example@10.0.0.1', or `10.0.0.1' if they
are on a machine which no concept of usernames).
13. Interoperable exchange of source description packets containing 13. Interoperable exchange of source description packets containing
a CNAME item. a CNAME item.
14. Interoperable exchange of source description packets containing 14. Interoperable exchange of source description packets containing
a NAME item. a NAME item.
15. Interoperable exchange of source description packets containing 15. Interoperable exchange of source description packets containing
an EMAIL item. an EMAIL item.
skipping to change at line 153 skipping to change at line 152
18. Interoperable exchange of source description packets containing 18. Interoperable exchange of source description packets containing
a TOOL item. a TOOL item.
19. Interoperable exchange of source description packets containing 19. Interoperable exchange of source description packets containing
a NOTE item. a NOTE item.
20. Interoperable exchange of source description packets containing 20. Interoperable exchange of source description packets containing
a PRIV item. a PRIV item.
21. Interoperable exchange of BYE packets. 21.Interoperable exchange of BYE packets containing a single SSRC.
22. Interoperable exchange of BYE packets containing multiple SSRCs. 22. Interoperable exchange of BYE packets containing multiple SSRCs.
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23. Interoperable exchange of BYE packets containing the optional 23. Interoperable exchange of BYE packets containing the optional
reason for leaving text. reason for leaving text.
24. Interoperable exchange of application defined RTCP packets. As 24.Interoperable exchange of BYE packets containing the optional
reason for leaving text and multiple SSRCs.
25.Interoperable exchange of application defined RTCP packets. As
with the RTP header extension this test takes two forms: if with the RTP header extension this test takes two forms: if
both implementations implement the same application defined packet both implementations implement the same application defined packet
it should be verified that those packets can be interoperably it should be verified that those packets can be interoperably
exchanged. If only one implementation uses application defined exchanged. If only one implementation uses application defined
packets, it should be verified that the other implementation packets, it should be verified that the other implementation
can receive compound RTCP packets containing an APP packet whilst can receive compound RTCP packets containing an APP packet whilst
ignoring the APP packet. If neither implementation implements ignoring the APP packet. If neither implementation implements
APP packets this test is considered a failure. APP packets this test is considered a failure.
25. Interoperable exchange of encrypted RTP packets using DES encryption 26.Interoperable exchange of encrypted RTP packets using DES encryption
in CBC mode. in CBC mode.
26. Interoperable exchange of encrypted RTCP packets using DES encryption 27.Interoperable exchange of encrypted RTCP packets using DES encryption
in CBC mode. in CBC mode.
3 Features and options relating to scalability 3 Features and options relating to scalability
In addition to the basic interoperability tests, RTP includes a number of In addition to the basic interoperability tests, RTP includes a number
features relating to scaling of the protocol to large groups. Since these of features relating to scaling of the protocol to large groups.
features are those which have undergone the greatest change in the update Since these features are those which have undergone the greatest
of the RTP specification, it is considered important to demonstrate their change in the update of the RTP specification, it is considered important
correct implementation. However, since these changes do not affect the to demonstrate their correct implementation. However, since these
bits-on-the-wire behaviour of the protocol, it is not possible to perform a changes do not affect the bits-on-the-wire behaviour of the protocol,
traditional interoperability test. As an alternative to such testing we it is not possible to perform a traditional interoperability test.
require that multiple independent implementations complete the following As an alternative to such testing we require that multiple independent
demonstrations. implementations complete the following demonstrations.
1. Demonstrate correct implementation of basic RTCP transmission 1. Demonstrate correct implementation of basic RTCP transmission
rules: periodic transmission of RTCP packets at the minimum rules: periodic transmission of RTCP packets at the minimum
(5 second) interval and randomisation of the transmission interval. (5 second) interval and randomisation of the transmission interval.
2. Demonstrate correct implementation of the RTCP step join backoff 2. Demonstrate correct implementation of the RTCP step join backoff
algorithm as a receiver. algorithm as a receiver.
3. Demonstrate correct implementation of the RTCP step join backoff 3. Demonstrate correct implementation of the RTCP step join backoff
algorithm as a sender. algorithm as a sender.
skipping to change at line 209 skipping to change at line 210
4. Demonstrate correct steady state scaling of the RTCP interval 4. Demonstrate correct steady state scaling of the RTCP interval
acording to the group size. acording to the group size.
5. Demonstrate correct steady state scaling of the RTCP interval 5. Demonstrate correct steady state scaling of the RTCP interval
acording to the group size with compensation for the number of acording to the group size with compensation for the number of
senders. senders.
6. Demonstrate correct implementation of the RTCP reverse reconsideration 6. Demonstrate correct implementation of the RTCP reverse reconsideration
algorithm. algorithm.
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7. Demonstrate correct implementation of the RTCP BYE reconsideration 7. Demonstrate correct implementation of the RTCP BYE reconsideration
algorithm. algorithm.
8. Demonstrate correct implementation of the RTCP member timeout 8. Demonstrate correct implementation of the RTCP member timeout
algorithm. algorithm.
9. Demonstrate random choice of SSRC. 9. Demonstrate random choice of SSRC.
10. Demonstrate random selection of initial RTP sequence number. 10. Demonstrate random selection of initial RTP sequence number.
skipping to change at line 252 skipping to change at line 252
5 Acknowledgments 5 Acknowledgments
Thanks to Steve Casner, Jonathan Rosenberg and Bill Fenner for their Thanks to Steve Casner, Jonathan Rosenberg and Bill Fenner for their
helpful feedback. helpful feedback.
6 References 6 References
[1] S. Bradner, ``The Internet Standards Process -- Revision 3'', [1] S. Bradner, ``The Internet Standards Process -- Revision 3'',
RFC2026, Internet Engineering Task Force, October 1996. RFC2026, Internet Engineering Task Force, October 1996.
[2] H. Schulzrinne, S. Casner, R. Frederick and V. Jacobson, [2] H. Schulzrinne, S. Casner, R. Frederick and V. Jacobson, ``RTP:
``RTP: A Transport Protocol to Real-Time Applications'', RFC1889, A Transport Protocol to Real-Time Applications'', RFC1889, Internet
Internet Engineering Task Force, January 1996. Engineering Task Force, January 1996.
[3] H. Schulzrinne, ``RTP Profile for Audio and Video Conferences with [3] H. Schulzrinne, ``RTP Profile for Audio and Video Conferences with
Minimal Control'', draft-ietf-avt-profile-new-05.txt, February 1999. Minimal Control'', draft-ietf-avt-profile-new-05.txt, February 1999.
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[4] C. S. Perkins, J. Rosenberg and H. Schulzrinne, ``RTP Testing [4] C. S. Perkins, J. Rosenberg and H. Schulzrinne, ``RTP Testing
Strategies'', draft-ietf-avt-rtptest-01.txt, August 1999. Strategies'', draft-ietf-avt-rtptest-01.txt, August 1999.
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