draft-ietf-ippm-loss-pattern-01.txt   draft-ietf-ippm-loss-pattern-02.txt 
Internet-Draft Internet-Draft
Expiration Date: December, 1999 R. Koodli Expiration Date: April, 2000 R. Koodli
R. Ravikanth R. Ravikanth
Nokia Research Center Nokia Research Center
June, 1999 October, 1999
One-way Loss Pattern Sample Metrics One-way Loss Pattern Sample Metrics
<draft-ietf-ippm-loss-pattern-01.txt> <draft-ietf-ippm-loss-pattern-02.txt>
STATUS OF THIS MEMO STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026. provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet- Drafts. may also distribute working documents as Internet- Drafts.
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and received (denoted by r) packets. and received (denoted by r) packets.
r r r x r r x x x r x r r x x x r r r x r r x x x r x r r x x x
Then, with i assigned as follows Then, with i assigned as follows
1 1 1 1 1 1 1 1 1 1 1 1
i: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 i: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
f(P_i) is, f(P_i) is,
f(P_i): 0 0 0 1 0 1 0 0 0 1 0 1 1 0 0 0 f(P_i): 0 0 0 1 0 0 1 1 1 0 1 0 0 1 1 1
and there are four loss periods in the above sequence and there are four loss periods in the above sequence
begining at P_3, P_6, P_10, and P_13. beginning at P_3, P_6, P_10, and P_13.
4. Definitions for Samples of One-way Loss Distance, 4. Definitions for Samples of One-way Loss Distance,
and One-way Loss Period. and One-way Loss Period.
4.1 Metric Name: 4.1 Metric Name:
4.1.1 Type-P-One-Way-Loss-Distance-Stream 4.1.1 Type-P-One-Way-Loss-Distance-Stream
4.1.2 Type-P-One-Way-Loss-Period-Stream 4.1.2 Type-P-One-Way-Loss-Period-Stream
4.2 Metric Parameters 4.2 Metric Parameters
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the lost packet and the previously lost packet. The sample would the lost packet and the previously lost packet. The sample would
consist of <loss distance, loss> pairs. This definition assumes that consist of <loss distance, loss> pairs. This definition assumes that
sequence numbers of successive test packets increase monotonically by sequence numbers of successive test packets increase monotonically by
one. The loss distance associated with the very first packet loss is one. The loss distance associated with the very first packet loss is
considered to be zero. considered to be zero.
The sequence number of a test packet can be derived from the timeseries The sequence number of a test packet can be derived from the timeseries
sample collected by performing the loss measurement according to the sample collected by performing the loss measurement according to the
methodology in [AKZ]. For example, if a loss sample consists of methodology in [AKZ]. For example, if a loss sample consists of
{<T0,0>, <T1,0>, <T2,1>, <T3,0>, <T4,0>}, the sequence numbers of the {<T0,0>, <T1,0>, <T2,1>, <T3,0>, <T4,0>}, the sequence numbers of the
five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and 4 five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and
respectively, or 100, 101, 102, 103 and 104 respectively, etc. 4 respectively, or 100, 101, 102, 103 and 104 respectively, etc.
{Packet loss may also be considered as a result of exceeding some delay {Packet loss may also be considered as a result of exceeding some delay
threshold. This is particularly applicable to delay-sensitive audio threshold. This is particularly applicable to delay-sensitive audio
(or video) applications. (or video) applications.
} }
4.4.2 Type-P-One-Way-Loss-Period-Stream 4.4.2 Type-P-One-Way-Loss-Period-Stream
We start a counter 'n' at an initial value of zero. This counter is We start a counter 'n' at an initial value of zero. This counter is
incremented by one each time a lost packet satisfies the Definition 3.3. incremented by one each time a lost packet satisfies the Definition 3.3.
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4.6 Discussion: 4.6 Discussion:
The Loss-Distance-Stream metric allows one to study the separation The Loss-Distance-Stream metric allows one to study the separation
between packet losses. This could be useful in determining a between packet losses. This could be useful in determining a
"spread factor" associated with the packet loss rate. For "spread factor" associated with the packet loss rate. For
example, for a given packet loss rate, the proposed metric example, for a given packet loss rate, the proposed metric
indicates how the losses are spread. On the other hand, indicates how the losses are spread. On the other hand,
the Loss-Period-Stream metric allows the study of loss burstiness the Loss-Period-Stream metric allows the study of loss burstiness
for each occurrence of loss. Note that a single loss period of for each occurrence of loss. Note that a single loss period of
length 'n' can account for a significant portion of the overall length 'n' can account for a significant portion of the overall
loss rate. loss rate. Note also that it is possible to measure distance between
loss bursts seprated by one or more successfully received packets: See
Section 5.4, and 5.5
4.7 Sampling Considerations: 4.7 Sampling Considerations:
The proposed metrics can be used independent of the The proposed metrics can be used independent of the
particular sampling method used. We note that Poisson sampling particular sampling method used. We note that Poisson sampling
may not yield appropriate values for these metrics for may not yield appropriate values for these metrics for
certain real-time applications such as voice over IP, as well as to certain real-time applications such as voice over IP, as well as to
TCP-based applications. For real-time applications, it may be more TCP-based applications. For real-time applications, it may be more
appropriate to use the ON-OFF [Sriram] model, in which an ON period appropriate to use the ON-OFF [Sriram] model, in which an ON period
starts with certain probability 'p', during which certain number of starts with certain probability 'p', during which certain number of
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"loss period" entry ranging from 1 - Type-P-One-Way-Loss-Period-Total. "loss period" entry ranging from 1 - Type-P-One-Way-Loss-Period-Total.
Thus the total number of pairs in this statistic equals Thus the total number of pairs in this statistic equals
Type-P-One-Way-Loss-Period-Total. In each pair, the "length" is Type-P-One-Way-Loss-Period-Total. In each pair, the "length" is
obtained by counting the number of pairs, <loss period, loss>, in the obtained by counting the number of pairs, <loss period, loss>, in the
metric Type-P-One-Way-Loss-Period-Stream which have first entry equal metric Type-P-One-Way-Loss-Period-Stream which have first entry equal
to "loss period." to "loss period."
{Note: This statistic represents the number of packets lost in each {Note: This statistic represents the number of packets lost in each
loss period.} loss period.}
5.4 Example 5.4 Type-P-One-Way-Inter-Loss-Period-Lengths
This statistic measures distance between successive loss periods. It
takes the form of a set of pairs
<loss period, inter-loss-period-length>, with the
"loss period" entry ranging from 1 - Type-P-One-Way-Loss-Period-Total,
and "inter-loss-period-length" is the loss distance between the last
packet considered lost in "loss period" 'i-1', and the first packet
considered lost in "loss period" 'i', where 'i' ranges from 2 to
Type-P-One-Way-Loss-Period-Total. The "inter-loss-period-length"
associated with the first "loss period" is defined to be zero. This
statistic allows one to consider, for example, two loss periods each
of length greater than one (implying loss burst), but separated by a
distance of 2 to belong to the same loss burst if such a consideration
is deemed useful.
5.5 Example
We continue with the same example as in Section 4.4.3. The three We continue with the same example as in Section 4.4.3. The three
statistics defined above will have the following values. statistics defined above will have the following values.
+ Let delta = 2. + Let delta = 2.
In Type-P-One-Way-Loss-Distance-Stream In Type-P-One-Way-Loss-Distance-Stream
{<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>}, there {<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>}, there
are 3 loss distances that violate the delta of 2. Thus, are 3 loss distances that violate the delta of 2. Thus,
Type-P-One-Way-Loss-Noticeable-Rate = 3/5 Type-P-One-Way-Loss-Noticeable-Rate = 3/5
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Type-P-One-Way-Loss-Period-Total = 4 Type-P-One-Way-Loss-Period-Total = 4
+ In Type-P-One-Way-Loss-Period-Stream + In Type-P-One-Way-Loss-Period-Stream
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>}, the {<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>}, the
lengths of individual loss periods are 1, 1, 1 and 2 respectively. lengths of individual loss periods are 1, 1, 1 and 2 respectively.
Thus, Thus,
Type-P-One-Way-Loss-Period-Lengths = {<1,1>,<2,1>,<3,1>,<4,2>} Type-P-One-Way-Loss-Period-Lengths = {<1,1>,<2,1>,<3,1>,<4,2>}
+ In Type-P-One-Way-Loss-Period-Stream
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>}, the
loss periods 1 and 2 are separated by 3 (5-2), loss periods 2 and 3
are separated by 2 (7-5), and 3 and 4 are separated by 2 (9-7).
Thus,
Type-P-One-Way-Inter-Loss-Period-Lengths = {<1,0>,<2,3>,<3,2>,<4,2>}
6. Security Considerations 6. Security Considerations
Since this draft proposes sample metrics based on the base loss metric Since this draft proposes sample metrics based on the base loss metric
defined in [AKZ], it inherits the security considerations mentioned in defined in [AKZ], it inherits the security considerations mentioned in
[AKZ]. [AKZ].
7. Acknowledgements 7. Acknowledgements
Many thanks to Matt Zekauskas for the constructive feedback on the draft. Many thanks to Matt Zekauskas for the constructive feedback on the draft.
Thanks to Guy Almes for encouraging the work, and Vern Paxson for all the Thanks to Guy Almes for encouraging the work, and Vern Paxson for the
comments during the IETF meetings. comments during the IETF meetings. Thanks to Steve Glass for making the
presentation at the Oslo meeting.
8. References 8. References
[AKZ] G. Almes and S. Kalindindi and M. Zekauskas, "A One-way Packet [AKZ] G. Almes and S. Kalindindi and M. Zekauskas, "A One-way Packet
Loss Metric for IPPM", Internet Draft <draft-ietf-ippm-loss-07.txt>, Loss Metric for IPPM", RFC 2680, September 1999
May 1999
[Bolot] J.-C. Bolot and A. vega Garcia, "The case for FEC-based [Bolot] J.-C. Bolot and A. vega Garcia, "The case for FEC-based
error control for Packet Audio in the Internet", ACM Multimedia error control for Packet Audio in the Internet", ACM Multimedia
Systems, 1997. Systems, 1997.
[Borella] M. S. Borella, D. Swider, S. Uludag, and G. B. Brewster, [Borella] M. S. Borella, D. Swider, S. Uludag, and G. B. Brewster,
"Internet Packet Loss: Measurement and Implications for End-to-End "Internet Packet Loss: Measurement and Implications for End-to-End
QoS," Proceedings, International Conference on Parallel Processing, QoS," Proceedings, International Conference on Parallel Processing,
August 1998. August 1998.
skipping to change at page 8, line 53 skipping to change at page 9, line 25
TCP-friendly rate adjustment protocol for continuous media flows TCP-friendly rate adjustment protocol for continuous media flows
over best-effort networks", short paper presentation in over best-effort networks", short paper presentation in
ACM SIGMETRICS'99. Available as Umass Computer Science tech report ACM SIGMETRICS'99. Available as Umass Computer Science tech report
from ftp://gaia.cs.umass.edu/pub/Padhye98-tcp-friendly-TR.ps.gz from ftp://gaia.cs.umass.edu/pub/Padhye98-tcp-friendly-TR.ps.gz
[Paxson] V. Paxson, "End-to-end Internet packet dynamics", Computer [Paxson] V. Paxson, "End-to-end Internet packet dynamics", Computer
Communication review, Proceedings of ACM SIGCOMM'97 Conference, Communication review, Proceedings of ACM SIGCOMM'97 Conference,
Cannes, France, September 1997, 27(4), pages 139-152, October 1997 Cannes, France, September 1997, 27(4), pages 139-152, October 1997
[frame-work] V. Paxson, G. Almes, J. Mahdavi, and M. Mathis, [frame-work] V. Paxson, G. Almes, J. Mahdavi, and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330. "Framework for IP Performance Metrics", RFC 2330, May 1998.
[Sriram] K. Sriram and W. Whitt, "Characterizing superposition [Sriram] K. Sriram and W. Whitt, "Characterizing superposition
arrival processes in packet multiplexers for voice and data", IEEE arrival processes in packet multiplexers for voice and data", IEEE
Journal on Selected Areas of Communication, September 1986, pages Journal on Selected Areas of Communication, September 1986, pages
833-846 833-846
[Yajnik] M. Yajnik, J. Kurose and D. Towsley, "Packet loss [Yajnik] M. Yajnik, J. Kurose and D. Towsley, "Packet loss
correlation in the MBONE multicast network", Proceedings of IEEE correlation in the MBONE multicast network", Proceedings of IEEE
Global Internet, London, UK, November 1996. Global Internet, London, UK, November 1996.
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