 1/draftietfippmlosspattern01.txt 20060204 23:45:33.000000000 +0100
+++ 2/draftietfippmlosspattern02.txt 20060204 23:45:33.000000000 +0100
@@ 1,18 +1,18 @@
InternetDraft
Expiration Date: December, 1999 R. Koodli
+Expiration Date: April, 2000 R. Koodli
R. Ravikanth
Nokia Research Center
 June, 1999
+ October, 1999
Oneway Loss Pattern Sample Metrics

+
STATUS OF THIS MEMO
This document is an InternetDraft and is in full conformance with all
provisions of Section 10 of RFC2026.
InternetDrafts 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.
@@ 128,24 +128,24 @@
and received (denoted by r) packets.
r r r x r r x x x r x r r x x x
Then, with i assigned as follows
1 1 1 1 1 1
i: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
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
 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 Oneway Loss Distance,
and Oneway Loss Period.
4.1 Metric Name:
4.1.1 TypePOneWayLossDistanceStream
4.1.2 TypePOneWayLossPeriodStream
4.2 Metric Parameters
@@ 181,22 +181,22 @@
the lost packet and the previously lost packet. The sample would
consist of pairs. This definition assumes that
sequence numbers of successive test packets increase monotonically by
one. The loss distance associated with the very first packet loss is
considered to be zero.
The sequence number of a test packet can be derived from the timeseries
sample collected by performing the loss measurement according to the
methodology in [AKZ]. For example, if a loss sample consists of
{, , , , }, the sequence numbers of the
five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and 4
respectively, or 100, 101, 102, 103 and 104 respectively, etc.
+five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and
+4 respectively, or 100, 101, 102, 103 and 104 respectively, etc.
{Packet loss may also be considered as a result of exceeding some delay
threshold. This is particularly applicable to delaysensitive audio
(or video) applications.
}
4.4.2 TypePOneWayLossPeriodStream
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.
@@ 250,21 +250,23 @@
4.6 Discussion:
The LossDistanceStream metric allows one to study the separation
between packet losses. This could be useful in determining a
"spread factor" associated with the packet loss rate. For
example, for a given packet loss rate, the proposed metric
indicates how the losses are spread. On the other hand,
the LossPeriodStream metric allows the study of loss burstiness
for each occurrence of loss. Note that a single loss period of
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:
The proposed metrics can be used independent of the
particular sampling method used. We note that Poisson sampling
may not yield appropriate values for these metrics for
certain realtime applications such as voice over IP, as well as to
TCPbased applications. For realtime applications, it may be more
appropriate to use the ONOFF [Sriram] model, in which an ON period
starts with certain probability 'p', during which certain number of
@@ 311,21 +313,37 @@
"loss period" entry ranging from 1  TypePOneWayLossPeriodTotal.
Thus the total number of pairs in this statistic equals
TypePOneWayLossPeriodTotal. In each pair, the "length" is
obtained by counting the number of pairs, , in the
metric TypePOneWayLossPeriodStream which have first entry equal
to "loss period."
{Note: This statistic represents the number of packets lost in each
loss period.}
5.4 Example
+5.4 TypePOneWayInterLossPeriodLengths
+
+This statistic measures distance between successive loss periods. It
+takes the form of a set of pairs
+, with the
+"loss period" entry ranging from 1  TypePOneWayLossPeriodTotal,
+and "interlossperiodlength" is the loss distance between the last
+packet considered lost in "loss period" 'i1', and the first packet
+considered lost in "loss period" 'i', where 'i' ranges from 2 to
+TypePOneWayLossPeriodTotal. The "interlossperiodlength"
+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
statistics defined above will have the following values.
+ Let delta = 2.
In TypePOneWayLossDistanceStream
{<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,
TypePOneWayLossNoticeableRate = 3/5
@@ 338,38 +356,44 @@
TypePOneWayLossPeriodTotal = 4
+ In TypePOneWayLossPeriodStream
{<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.
Thus,
TypePOneWayLossPeriodLengths = {<1,1>,<2,1>,<3,1>,<4,2>}
++ In TypePOneWayLossPeriodStream
+ {<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 (52), loss periods 2 and 3
+ are separated by 2 (75), and 3 and 4 are separated by 2 (97).
+ Thus,
+ TypePOneWayInterLossPeriodLengths = {<1,0>,<2,3>,<3,2>,<4,2>}
+
6. Security Considerations
Since this draft proposes sample metrics based on the base loss metric

defined in [AKZ], it inherits the security considerations mentioned in
[AKZ].
7. Acknowledgements
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
comments during the IETF meetings.
+Thanks to Guy Almes for encouraging the work, and Vern Paxson for the
+comments during the IETF meetings. Thanks to Steve Glass for making the
+presentation at the Oslo meeting.
8. References
[AKZ] G. Almes and S. Kalindindi and M. Zekauskas, "A Oneway Packet
 Loss Metric for IPPM", Internet Draft ,
 May 1999
+ Loss Metric for IPPM", RFC 2680, September 1999
[Bolot] J.C. Bolot and A. vega Garcia, "The case for FECbased
error control for Packet Audio in the Internet", ACM Multimedia
Systems, 1997.
[Borella] M. S. Borella, D. Swider, S. Uludag, and G. B. Brewster,
"Internet Packet Loss: Measurement and Implications for EndtoEnd
QoS," Proceedings, International Conference on Parallel Processing,
August 1998.
@@ 390,21 +413,21 @@
TCPfriendly rate adjustment protocol for continuous media flows
over besteffort networks", short paper presentation in
ACM SIGMETRICS'99. Available as Umass Computer Science tech report
from ftp://gaia.cs.umass.edu/pub/Padhye98tcpfriendlyTR.ps.gz
[Paxson] V. Paxson, "Endtoend Internet packet dynamics", Computer
Communication review, Proceedings of ACM SIGCOMM'97 Conference,
Cannes, France, September 1997, 27(4), pages 139152, October 1997
[framework] 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
arrival processes in packet multiplexers for voice and data", IEEE
Journal on Selected Areas of Communication, September 1986, pages
833846
[Yajnik] M. Yajnik, J. Kurose and D. Towsley, "Packet loss
correlation in the MBONE multicast network", Proceedings of IEEE
Global Internet, London, UK, November 1996.