draft-ietf-ippm-loss-pattern-02.txt | draft-ietf-ippm-loss-pattern-03.txt | |||
---|---|---|---|---|

Internet-Draft | Internet-Draft | |||

Expiration Date: April, 2000 R. Koodli | Expiration Date: December, 2000 R. Koodli | |||

R. Ravikanth | R. Ravikanth | |||

Nokia Research Center | Nokia Research Center | |||

October, 1999 | July 2000 | |||

One-way Loss Pattern Sample Metrics | One-way Loss Pattern Sample Metrics | |||

<draft-ietf-ippm-loss-pattern-02.txt> | <draft-ietf-ippm-loss-pattern-03.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. | |||

skipping to change at page 3, line 21 | skipping to change at page 3, line 21 | |||

3.2. Loss Distance: | 3.2. Loss Distance: | |||

The difference in sequence numbers of two successively lost | The difference in sequence numbers of two successively lost | |||

packets which may or may not be separated by successfully | packets which may or may not be separated by successfully | |||

received packets. | received packets. | |||

Example. Let packet with sequence number 50 be considered lost | Example. Let packet with sequence number 50 be considered lost | |||

immediately after packet with sequence number 20 was | immediately after packet with sequence number 20 was | |||

considered lost. The loss distance is 30. | considered lost. The loss distance is 30. | |||

{Comment: note that this definition does not specify exactly how to | Note that this definition does not specify exactly how to | |||

associate sequence numbers with test packets. In other words, from | associate sequence numbers with test packets. In other words, from | |||

a timeseries sample of test packets, one may derive the sequence | a timeseries sample of test packets, one may derive the sequence | |||

numbers. For example, assign consecutive integers to each packet in | numbers. However, these sequence numbers must be consecutive | |||

the time series.} | integers. | |||

3.3. Loss period: | 3.3. Loss period: | |||

Let P_i be the i'th packet. | Let P_i be the i'th packet. | |||

Define f(P_i) = 1 if P_i is lost, 0 otherwise. | Define f(P_i) = 1 if P_i is lost, 0 otherwise. | |||

Then, a loss period begins if f(P_i) = 1 and f(P_(i-1)) = 0 | Then, a loss period begins if f(P_i) = 1 and f(P_(i-1)) = 0 | |||

Example. Consider the following sequence of lost (denoted by x) | Example. Consider the following sequence of lost (denoted by x) | |||

and received (denoted by r) packets. | and received (denoted by r) packets. | |||

skipping to change at page 4, line 48 | skipping to change at page 4, line 48 | |||

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 | 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. | 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 delay-sensitive audio | ||||

(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. | |||

The metric is defined as <loss period, loss> where | The metric is defined as <loss period, loss> where | |||

"loss" is derived from the sequence of <time, loss> in | "loss" is derived from the sequence of <time, loss> in | |||

Type-P-One-Way-Loss-Stream [AKZ], and | Type-P-One-Way-Loss-Stream [AKZ], and | |||

loss period is set to zero when "loss" is zero in | loss period is set to zero when "loss" is zero in | |||

Type-P-One-Way-Loss-Stream, and loss period is set to 'n' (above) | Type-P-One-Way-Loss-Stream, and loss period is set to 'n' (above) | |||

when "loss" is one in Type-P-One-Way-Loss-Stream. | when "loss" is one in Type-P-One-Way-Loss-Stream. | |||

{Note: When a packet is lost, the current value of "n" indicates the | Essentially, when a packet is lost, the current value of "n" indicates | |||

loss period to which this packet belongs. For a packet that is | the loss period to which this packet belongs. For a packet that is | |||

received successfully, the loss period is defined to be zero.} | received successfully, the loss period is defined to be zero. | |||

4.4.3 Example: | 4.4.3 Example: | |||

Let the following set of pairs represent a Type-P-One-Way-Loss-Stream. | Let the following set of pairs represent a Type-P-One-Way-Loss-Stream. | |||

{<T1,0>,<T2,1>,<T3,0>,<T4,0>,<T5,1>,<T6,0>,<T7,1>,<T8,0>,<T9,1>, | {<T1,0>,<T2,1>,<T3,0>,<T4,0>,<T5,1>,<T6,0>,<T7,1>,<T8,0>,<T9,1>, | |||

<T10,1>} | <T10,1>} | |||

where T1, T2,..,T10 are in increasing order. | where T1, T2,..,T10 are in increasing order. | |||

skipping to change at page 6, line 10 | skipping to change at page 6, line 10 | |||

4.5. Methodologies: | 4.5. Methodologies: | |||

The same methodology outlined in [AKZ] can be used to conduct the | The same methodology outlined in [AKZ] can be used to conduct the | |||

sample experiments. | sample experiments. | |||

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, this 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. Note also that it is possible to measure distance between | loss rate. Note also that it is possible to measure distance between | |||

loss bursts seprated by one or more successfully received packets: See | loss bursts seprated by one or more successfully received packets: See | |||

Section 5.4, and 5.5 | Section 5.4, and 5.5 | |||

4.7 Sampling Considerations: | 4.7 Sampling Considerations: | |||

skipping to change at page 6, line 44 | skipping to change at page 6, line 45 | |||

5. Statistics: | 5. Statistics: | |||

5.1 Type-P-One-Way-Loss-Noticeable-Rate | 5.1 Type-P-One-Way-Loss-Noticeable-Rate | |||

Define loss of a packet to be "noticeable" [RK97] if the distance | Define loss of a packet to be "noticeable" [RK97] if the distance | |||

between the lost packet and the previously lost packet is no | between the lost packet and the previously lost packet is no | |||

greater than delta, a positive integer, where delta is the | greater than delta, a positive integer, where delta is the | |||

"loss constraint". | "loss constraint". | |||

Example. Let delta = 100. Let us assume that packet 50 is lost | Example. Let delta = 99. Let us assume that packet 50 is lost | |||

followed by a bursty loss of length 3 starting from | followed by a bursty loss of length 3 starting from | |||

packet 125. | packet 125. | |||

All the *four* losses are noticeable. | All the *four* losses are noticeable. | |||

Given a Type-P-One-Way-Loss-Distance-Stream, this statistic | Given a Type-P-One-Way-Loss-Distance-Stream, this statistic | |||

can be computed simply as the number of losses that violate some | can be computed simply as the number of losses that violate some | |||

constraint delta, divided by the number of losses. (Alternately, it | constraint delta, divided by the number of losses. (Alternately, it | |||

can also be defined as the number of "noticeable losses" to the number | can also be defined as the number of "noticeable losses" to the number | |||

of successfully received packets). | of successfully received packets). | |||

This statistic is useful when the actual distance between successive | ||||

losses is important. For example, many multimedia codecs can sustain | ||||

losses by "concealing" the effect of loss by making use of past | ||||

history information. Their ability to do so degrades with poor | ||||

history resulting from losses separated by close distances. By chosing | ||||

delta based on this sensitivity, one can measure how "noticeable" a | ||||

loss might be for quality purposes. The noticeable loss requires | ||||

a certain "spread factor" for losses in the timeseries. In the above | ||||

example where loss constraint is equal to 99, a loss rate of one | ||||

percent with a spread of 100 between losses (e.g., 100, 200, 300, | ||||

400, 500 out of 500 packets) may be more desirable for some | ||||

applications compared to the same loss rate with a spread that | ||||

violates the loss constraint (e.g., 100, 175, 275, 290, 400: losses | ||||

occuring at 175 and 290 violate delta = 99). | ||||

5.2 Type-P-One-Way-Loss-Period-Total | 5.2 Type-P-One-Way-Loss-Period-Total | |||

This represents the total number of loss periods, and can be derived | This represents the total number of loss periods, and can be derived | |||

from the loss period metric Type-P-One-Way-Loss-Period-Stream as | from the loss period metric Type-P-One-Way-Loss-Period-Stream as | |||

follows: | follows: | |||

Type-P-One-Way-Loss-Period-Total = maximum value of the first entry | Type-P-One-Way-Loss-Period-Total = maximum value of the first entry | |||

of the set of pairs, <loss period, loss>, representing the loss metric | of the set of pairs, <loss period, loss>, representing the loss metric | |||

Type-P-One-Way-Loss-Period-Stream. | Type-P-One-Way-Loss-Period-Stream. | |||

5.3 Type-P-One-Way-Loss-Period-Lengths | 5.3 Type-P-One-Way-Loss-Period-Lengths | |||

This statistic is a sequence of pairs <loss period, length>, with the | This statistic is a sequence of pairs <loss period, length>, with the | |||

"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 | Thus, this statistic represents the number of packets lost in each | |||

loss period.} | loss period. | |||

5.4 Type-P-One-Way-Inter-Loss-Period-Lengths | 5.4 Type-P-One-Way-Inter-Loss-Period-Lengths | |||

This statistic measures distance between successive loss periods. It | This statistic measures distance between successive loss periods. It | |||

takes the form of a set of pairs | takes the form of a set of pairs | |||

<loss period, inter-loss-period-length>, with the | <loss period, inter-loss-period-length>, with the | |||

"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, | |||

and "inter-loss-period-length" is the loss distance between the last | and "inter-loss-period-length" is the loss distance between the last | |||

packet considered lost in "loss period" 'i-1', and the first packet | packet considered lost in "loss period" 'i-1', and the first packet | |||

considered lost in "loss period" 'i', where 'i' ranges from 2 to | considered lost in "loss period" 'i', where 'i' ranges from 2 to | |||

skipping to change at page 9, line 4 | skipping to change at page 9, line 18 | |||

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. | |||

[Handley] M. Handley, "An examination of MBONE performance", | [Handley] M. Handley, "An examination of MBONE performance", | |||

Technical Report, USC/ISI, ISI/RR-97-450, January 1997 | Technical Report, USC/ISI, ISI/RR-97-450, January 1997 | |||

[RK97] R. Koodli, "Scheduling Support for Multi-tier Quality of | [RK97] R. Koodli, "Scheduling Support for Multi-tier Quality of | |||

Service in Continuous Media Applications", PhD dissertation, | Service in Continuous Media Applications", PhD dissertation, | |||

Electrical and Computer Engineering Department, University of | Electrical and Computer Engineering Department, University of | |||

Massachusetts, Amherst, MA 01003. | Massachusetts, Amherst, MA 01003. | |||

ftp://aurelius.ecs.umass.edu/pub/koodli/thesis.ps.Z | ||||

[Padhye1] J. Padhye, V. Firoiu, J. Kurose and D. Towsley, "Modeling | [Padhye1] J. Padhye, V. Firoiu, J. Kurose and D. Towsley, "Modeling | |||

TCP throughput: a simple model and its empirical validation", in | TCP throughput: a simple model and its empirical validation", in | |||

Proceedings of SIGCOMM'98, 1998. | Proceedings of SIGCOMM'98, 1998. | |||

[Padhye2] J. Padhye, J. Kurose, D. Towsley and R. Koodli, "A | [Padhye2] J. Padhye, J. Kurose, D. Towsley and R. Koodli, "A | |||

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 | |||

skipping to change at page 9, line 40 | skipping to change at line 451 | |||

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. | |||

Author's Addresses | Author's Addresses | |||

Rajeev Koodli | Rajeev Koodli | |||

Nokia Research Center | Nokia Research Center | |||

3, Burlington Woods Drive, #250 | 313, Fairchild Drive | |||

Burlington, MA 01803 | Mountain View, CA 94043 | |||

Phone: +1 781-359-5136 | Phone: +1 650-625-2359 | |||

Email: rajeev.koodli@nokia.com | Email: rajeev.koodli@nokia.com | |||

Rayadurgam Ravikanth | Rayadurgam Ravikanth | |||

Nokia Research Center | Nokia Research Center | |||

3, Burlington Woods Drive, #250 | 5, Wayside Road | |||

Burlington, MA 01803 | Burlington, MA 01803 | |||

Phone: +1 781-238-4905 | Phone: +1 781-993-4606 | |||

Email: rayadurgam.ravikanth@nokia.com | Email: rayadurgam.ravikanth@nokia.com | |||

End of changes. | ||||

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/ |