< draft-mirsky-sfc-pmamm-01.txt   draft-mirsky-sfc-pmamm-02.txt >
SFC Working Group G. Mirsky SFC Working Group G. Mirsky
Internet-Draft ZTE Corp. Internet-Draft ZTE Corp.
Intended status: Standards Track G. Fioccola Intended status: Standards Track G. Fioccola
Expires: December 30, 2017 Telecom Italia Expires: March 16, 2018 Telecom Italia
T. Mizrahi T. Mizrahi
Marvell Marvell
June 28, 2017 September 12, 2017
Performance Measurement (PM) with Alternate Marking Method in Service Performance Measurement (PM) with Alternate Marking Method in Service
Function Chaining (SFC) Domain Function Chaining (SFC) Domain
draft-mirsky-sfc-pmamm-01 draft-mirsky-sfc-pmamm-02
Abstract Abstract
This document describes how the alternate marking method be used as This document describes how the alternate marking method be used as
the passive performance measurement method in a Service Function the passive performance measurement method in a Service Function
Chaining (SFC) domain. Chaining (SFC) domain.
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 2
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Mark Field in NSH Base Header . . . . . . . . . . . . . . . . 3 3. Mark Field in NSH Base Header . . . . . . . . . . . . . . . . 3
4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4
4.1. Single Mark Enabled Measurement . . . . . . . . . . . . . 4 4.1. Single Mark Enabled Measurement . . . . . . . . . . . . . 4
4.2. Double Mark Enabled Measurement . . . . . . . . . . . . . 5 4.2. Double Mark Enabled Measurement . . . . . . . . . . . . . 5
4.3. Residence Time Measurement with the Alternate Marking
Method . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5.1. Mark Field in NSH Base Header . . . . . . . . . . . . . . 6 5.1. Mark Field in NSH Base Header . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
[RFC7665] introduced architecture of a Service Function Chain (SFC) [RFC7665] introduced architecture of a Service Function Chain (SFC)
in the network and defined its components as classifier, Service in the network and defined its components as classifier, Service
Function Forwarder (SFF), and Service Function (SF). Function Forwarder (SFF), and Service Function (SF).
[I-D.ietf-ippm-alt-mark] describes passive performance measurement [I-D.ietf-ippm-alt-mark] describes passive performance measurement
method, which can be used to measure packet loss, latency and jitter method, which can be used to measure packet loss, latency and jitter
on live traffic. Because this method is based on marking consecutive on live traffic. Because this method is based on marking consecutive
batches of packets the method often referred as Alternate Marking batches of packets the method often referred as Alternate Marking
skipping to change at page 3, line 47 skipping to change at page 4, line 8
Because setting of the field to any value does not affect forwarding Because setting of the field to any value does not affect forwarding
and/or quality of service treatment of a packet, the alternate and/or quality of service treatment of a packet, the alternate
marking method in SFC layer can be viewed as true example of passive marking method in SFC layer can be viewed as true example of passive
performance measurement method. performance measurement method.
The Figure 2 displays format of the Mark field. The Figure 2 displays format of the Mark field.
0 0
0 1 0 1
+-+-+-+-+ +-+-+-+-+
| S | D | | L | D |
+-+-+-+-+ +-+-+-+-+
Figure 2: Mark field format Figure 2: Mark field format
where: where:
o S- Single mark method; o L- Loss flag;
o D - Double mark method. o D - Delay flag.
4. Theory of Operation 4. Theory of Operation
The marking method can be successfully used in the SFC. Without The marking method can be successfully used in the SFC. Without
limiting any generality consider SFC presented in Figure 3. Any limiting any generality consider SFC presented in Figure 3. Any
combination of markings, Loss and/or Delay, can be applied to a combination of markings, Loss and/or Delay, can be applied to a
service flow by any component of the SFC at either ingress or egress service flow by any component of the SFC at either ingress or egress
point to perform node, link, segment or end-to-end measurement to point to perform node, link, segment or end-to-end measurement to
detect performance degradation defect and localize it efficiently. detect performance degradation defect and localize it efficiently.
skipping to change at page 4, line 46 skipping to change at page 5, line 7
4.1. Single Mark Enabled Measurement 4.1. Single Mark Enabled Measurement
As explained in the [I-D.ietf-ippm-alt-mark], marking can be applied As explained in the [I-D.ietf-ippm-alt-mark], marking can be applied
to delineate blocks of packets based either on equal number of to delineate blocks of packets based either on equal number of
packets in a block or based on equal time interval. The latter packets in a block or based on equal time interval. The latter
method offers better control as it allows better account for method offers better control as it allows better account for
capabilities of downstream nodes to report statistics related to capabilities of downstream nodes to report statistics related to
batches of packets and, at the same time, time resolution that batches of packets and, at the same time, time resolution that
affects defect detection interval. affects defect detection interval.
If the Single Mark measurement used, then the D flag MUST be set to If the Single Mark measurement used, then the Delay flag Figure 2
zero on transmit and ignored by monitoring point. MUST be set to zero on transmit and ignored on reception by
monitoring point.
The S flag is used to create alternate flows to measure the packet The Loss flag is used to create alternate flows to measure the packet
loss by switching value of the S flag every N-th packet or at certain loss by switching value of the Loss flag every N-th packet or at
time intervals. Delay metrics MAY be calculated with the alternate certain time intervals. Delay metrics MAY be calculated with the
flow using any of the following methods: alternate flow using any of the following methods:
o First/Last Packet Delay calculation: whenever the marking, i.e. o First/Last Packet Delay calculation: whenever the marking, i.e.
value of S flag, changes a component of the SFC can store the value of Loss flag, changes a component of the SFC can store the
timestamp of the first/last packet of the block. The timestamp timestamp of the first/last packet of the block. The timestamp
can be compared with the timestamp of the packet that arrived in can be compared with the timestamp of the packet that arrived in
the same order through a monitoring point at downstream component the same order through a monitoring point at downstream component
of the SFC to compute packet delay. Because timestamps collected of the SFC to compute packet delay. Because timestamps collected
based on order of arrival this method is sensitive to packet loss based on order of arrival this method is sensitive to packet loss
and re-ordering of packets and re-ordering of packets
o Average Packet Delay calculation: an average delay is calculated o Average Packet Delay calculation: an average delay is calculated
by considering the average arrival time of the packets within a by considering the average arrival time of the packets within a
single block. A component of the SFC may collect timestamps for single block. A component of the SFC may collect timestamps for
skipping to change at page 5, line 34 skipping to change at page 5, line 43
also to packet loss (only a small error is introduced). This also to packet loss (only a small error is introduced). This
method only provides single metric for the duration of the block method only provides single metric for the duration of the block
and it doesn't give the minimum and maximum delay values. This and it doesn't give the minimum and maximum delay values. This
limitation could be overcome by reducing the duration of the block limitation could be overcome by reducing the duration of the block
by means of an highly optimized implementation of the method. by means of an highly optimized implementation of the method.
4.2. Double Mark Enabled Measurement 4.2. Double Mark Enabled Measurement
Double Mark method allows measurement of minimum and maximum delays Double Mark method allows measurement of minimum and maximum delays
for the monitored flow but it requires more nodal and network for the monitored flow but it requires more nodal and network
resources. If the Double Mark method used, then the S flag MUST be resources. If the Double Mark method used, then the Loss flag MUST
used to create the alternate flow, i.e. mark larger batches of be used to create the alternate flow, i.e. mark larger batches of
packets. The D flag MUST be used to mark single packets to measure packets. The Delay flag MUST be used to mark single packets to
delay jitter. measure delay jitter.
The first marking (S flag alternation) is needed for packet loss and The first marking (Loss flag alternation) is needed for packet loss
also for average delay measurement. The second marking (D flag is and also for average delay measurement. The second marking (Delay
put to one) creates a new set of marked packets that are fully flag is put to one) creates a new set of marked packets that are
identified over the SFC, so that a component can store the timestamps fully identified over the SFC, so that a component can store the
of these packets; these timestamps can be compared with the timestamps of these packets; these timestamps can be compared with
timestamps of the same packets on another component of the SFC to the timestamps of the same packets on another component of the SFC to
compute packet delay values for each packet. The number of compute packet delay values for each packet. The number of
measurements can be easily increased by changing the frequency of the measurements can be easily increased by changing the frequency of the
second marking. But the frequency of the second marking must be not second marking. But the frequency of the second marking must be not
too high in order to avoid out of order issues. This method is too high in order to avoid out of order issues. This method is
useful to have not only the average delay but also the minimum and useful to have not only the average delay but also the minimum and
maximum delay values and, in wider terms, to know more about the maximum delay values and, in wider terms, to know more about the
statistic distribution of delay values. statistic distribution of delay values.
4.3. Residence Time Measurement with the Alternate Marking Method
Residence time is the variable part of the propagation delay that a
packet experiences traversing a network, e.g. SFC. Residence Time
over an SFC is the sum of the nodal residence times, i.e. periods
that the packet spent in each of SFFs that compose the SFC. The
nodal residence time in SFC itself is the sum of sub-nodal residence
times that the packet spent in each of SFs that are part of the given
SFC and are mapped to the SFF. The residence time and deviation of
the residence time metrics may include any combination of minimum,
maximum, values over measurement period, as well as mean, median,
percentile. These metrics may be used to evaluate performance of the
SFC and its elements before and during its operation.
Use of the specially marked packets simplifies residence time
measurement and correlation of the measured metrics over the SFC end-
to-end. For example, the alternate marking method may be used as
described in Section 4.2 to identify packets in the data flow to be
used to measure the residence time. The nodal and sub-nodal
residence time metrics can be locally calculated and then collected
using either in-band or out-band OAM mechanisms.
5. IANA Considerations 5. IANA Considerations
5.1. Mark Field in NSH Base Header 5.1. Mark Field in NSH Base Header
This document requests IANA to allocate Mark field as two bits-long This document requests IANA to allocate Mark field as two bits-long
field from NSH Base Header Reserved Bits [I-D.ietf-sfc-nsh]. field from NSH Base Header Reserved Bits [I-D.ietf-sfc-nsh].
This document requests IANA to register values of the Mark field of This document requests IANA to register values of the Mark field of
NSH as the following: NSH as the following:
skipping to change at page 6, line 39 skipping to change at page 7, line 29
7. Acknowledgement 7. Acknowledgement
TBD TBD
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-sfc-nsh] [I-D.ietf-sfc-nsh]
Quinn, P. and U. Elzur, "Network Service Header", draft- Quinn, P., Elzur, U., and C. Pignataro, "Network Service
ietf-sfc-nsh-12 (work in progress), February 2017. Header (NSH)", draft-ietf-sfc-nsh-20 (work in progress),
September 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References 8.2. Informative References
[I-D.ietf-ippm-alt-mark] [I-D.ietf-ippm-alt-mark]
Fioccola, G., Capello, A., Cociglio, M., Castaldelli, L., Fioccola, G., Capello, A., Cociglio, M., Castaldelli, L.,
Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate Marking method for passive and hybrid "Alternate Marking method for passive and hybrid
performance monitoring", draft-ietf-ippm-alt-mark-05 (work performance monitoring", draft-ietf-ippm-alt-mark-10 (work
in progress), June 2017. in progress), September 2017.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665, Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015, DOI 10.17487/RFC7665, October 2015,
<http://www.rfc-editor.org/info/rfc7665>. <https://www.rfc-editor.org/info/rfc7665>.
Authors' Addresses Authors' Addresses
Greg Mirsky Greg Mirsky
ZTE Corp. ZTE Corp.
Email: gregimirsky@gmail.com Email: gregimirsky@gmail.com
Giuseppe Fioccola Giuseppe Fioccola
Telecom Italia Telecom Italia
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