Internet DRAFT - draft-fioccola-v6ops-ipv6-alt-mark
draft-fioccola-v6ops-ipv6-alt-mark
V6OPS Working Group G. Fioccola
Internet-Draft Telecom Italia
Intended status: Standards Track G. Van de Velde
Expires: December 7, 2018 Nokia
M. Cociglio
Telecom Italia
P. Muley
Nokia
June 5, 2018
IPv6 Performance Measurement with Alternate Marking Method
draft-fioccola-v6ops-ipv6-alt-mark-01
Abstract
This document describes how the alternate marking method in [RFC8321]
can be used as the passive performance measurement method in an IPv6
domain, and will discuss the strengths and the weaknesses of the
implementation options available to network operations. It proposes
how to extend [RFC7837] to apply alternate marking technique.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 7, 2018.
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Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPv6 application of Alternate Marking . . . . . . . . . . . . 3
2.1. IPv6 Extension Headers as Marking Field . . . . . . . . . 3
2.2. Other Possibilities . . . . . . . . . . . . . . . . . . . 5
2.2.1. IPv6 Addresses as Marking Field . . . . . . . . . . . 5
2.2.2. IPv6 Flow Label as Marking Field . . . . . . . . . . 5
3. Alternate Marking Method Operation . . . . . . . . . . . . . 6
3.1. Single Mark Measurement . . . . . . . . . . . . . . . . . 6
3.2. Double Mark Measurement . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
This document reports a summary on the possible implementation
options for the application of the alternate marking method in an
IPv6 domain.
[RFC8321] describes passive performance measurement method, which can
be used to measure packet loss, latency and jitter on live traffic.
Because this method is based on marking consecutive batches of
packets the method often referred as Alternate Marking Method.
This document defines how the alternate marking method can be used to
measure packet loss and delay metrics of IPv6 tunneled packets or
SRv6 policies.
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The IPv6 Header Format defined in [RFC8200] introduces the format of
IPv6 addresses, the Extension Headers in the base IPv6 Header and the
availability of a 20-bit flow label, that can be considered for the
application of the Alternate Marking methodology.
2. IPv6 application of Alternate Marking
The application of the alternate marking requires a marking field.
The alternatives that can be taken into consideration for the choice
of the marking field are the following:
o Extension Header
o IPv6 Address
o Flow Label
2.1. IPv6 Extension Headers as Marking Field
A new type of EH may be a solution space proposal (e.g. [RFC8250]
and [RFC7837] give a chance).
A possibility can be to use a Hop-By-Hop(HBH) Extension Header(EH).
The assumption is that a HBH EH with an alternate marking measurement
option can be defined. The router processing can be optimized to
handle this use case.
Using a new EH assumes that ALL routers in the domain support this
type of headers, which complicates backward compatibility of the
technology. The extension of an existing EH (e.g. [RFC7837]) can
overcome this issue.
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0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length |X|L|E|C| MF|res|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mark Field (MF) is:
0
0 1
+-+-+-+-+
| S | D |
+-+-+-+-+
Figure 1: ConEx HBH Option Layout with Mark Field
where:
o S - Single mark method;
o D - Double mark method.
The Figure 1 defines a new ConEx HBH (Hop-By-Hop) Option Layout.
This proposal starts from ConEx Destination Option Layout defined in
[RFC7837], where the Reserved (res) field is made by four bits that
are not used in that specification, in fact they are set to zero by
the sender and are ignored by the receiver.
This document aims to introduce the Mark Field (2 bits from 4 bits
res field). So the Mark Field (MF) reduces the number of Reserved
bits and the Reserved (res) field is now made by 2 bits.
It is important to highlight that the Destination Option Layout is
used as Hop-By-Hop Option Layout, since the alternate marking
methodology in [RFC8321] allows, by definition, Hop-By-Hop
performance measurements.
[I-D.krishnan-conex-ipv6] also tried to introduce a ConEx HBH Options
and inspired this proposal.
[I-D.fear-ippm-mpdm] introduces Marking Performance and Diagnostic
Metrics (M-PDM) and aims to combine [RFC8250] with [RFC8321], while
the extension of [RFC7837], proposed in this document, is optimized
to include only marking method without any considerations on how to
report and manage, this can be done in-band or out-of-band depending
on the case.
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2.2. Other Possibilities
This section reports the other possibilities that have been
discussed.
2.2.1. IPv6 Addresses as Marking Field
There is an advantage of using destination addresses (DA) to encode
the alternate marking method. In addition to identifying a host, a
destination address is also and more fundamentally identifying an
exit point from the forwarding domain. It indicates where processing
for forwarding to the DA stops, and where other processing of the
packet is to occur. Using the DA to encode this alternate marking
processing means that it is easy to retrofit into existing devices
and models. There is no need to replace existing IPv6 forwarding
devices, because they already support DA based forwarding.
However using DA for marking seems a lot expensive.
2.2.2. IPv6 Flow Label as Marking Field
Considering the Flow Label, [RFC6294] makes a survey of Proposed Use
Cases for the IPv6 Flow Label. The flow label is an immutable field
recommended to contain a pseudo-random value, however, often it has
the default value of zero. [RFC6436] and [RFC6437] open the door for
IPv6 Flow Label to be used in a controlled environment and [RFC6438]
describes the use of the IPv6 Flow Label field for load distribution
purpose, especially across Equal Cost Multi-Path (ECMP) and/or Link
Aggregation Group (LAG) paths. In addition it is possible to mention
[I-D.krishnan-6man-header-reserved-bits] that tried to set aside 4
bits from the flow label field for future expansion.
There are few drawbacks to use Flow Label instead of an EH solution
or IPv6 Addresses for IPv6 alternate marking, in particular an easier
backward compatibility and less bits on the wire. In this way
nothing breaks if a transit router does not have the capability of
understanding the Flow Label context.
Since the flow-label based load balancing has been defined, the
application of the Alternate Marking method to the flow label could
be realised with two fundamental assumptions:
o The original flow-label reconstructed when leaving the controlled
domain.
o The usage of IPv6 tunnels (IPv6inIPv6, IPSec, IPv6 UDP, etc..) or
SRv6 policies.
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In this case, the controlled domain reflects to the fact that it is a
network operator choice that grabs control of packet handling within
its own network. In fact, regarding the flow label, four options can
be supposed:
1) Just do not do anything with Flow Label (leave it default).
2) Entropy only and NO alternate marking for performance
measurements.
3) Alternate marking only and NO usage of entropy.
4) Alternate marking and entropy (in this case the entropy SHOULD
be based upon a subset of bits because otherwise paths may be
changed when the marking changes).
3. Alternate Marking Method Operation
[RFC8321] describes in detail the methodology, that we briefly
illustrate also here.
3.1. Single Mark Measurement
As explained in the [RFC8321], marking can be applied to delineate
blocks of packets based either on equal number of packets in a block
or based on equal time interval. The latter method offers better
control as it allows better account for capabilities of downstream
nodes to report statistics related to batches of packets and, at the
same time, time resolution that affects defect detection interval.
If the Single Mark measurement used, then the D flag MUST be set to
zero on transmit and ignored by monitoring point.
The S flag is used to create alternate flows to measure the packet
loss by switching value of the S flag. Delay metrics MAY be
calculated with the alternate flow using any of the following
methods:
o First/Last Batch Packet Delay calculation: timestamps are
collected based on order of arrival so this method is sensitive to
packet loss and re-ordering.
o Average Packet Delay calculation: an average delay is calculated
by considering the average arrival time of the packets within a
single block. This method only provides single metric for the
duration of the block and it doesn't give information about the
delay distribution.
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3.2. Double Mark Measurement
Double Mark method allows more detailed measurement of delays for the
monitored flow but it requires more nodal and network resources. If
the Double Mark method used, then the S flag MUST be used to create
the alternate flow. The D flag MUST be used to mark single packets
to measure delay jitter.
The first marking (S flag alternation) is needed for packet loss and
also for average delay measurement. The second marking (D flag is
put to one) creates a new set of marked packets that are fully
identified and dedicated for delay. This method is useful to have
not only the average delay but also to know more about the statistic
distribution of delay values.
4. Security Considerations
tbc
5. IANA Considerations
tbc
6. Acknowledgements
The authors would like to thank Fred Baker, Ole Troan, Robert Hinden,
Suresh Krishnan, Brian Carpenter, Roberta Maglione, Tom Herbert, Mark
Smith, Joel Halpern, Fernando Gont, Xiaohu Xu and Joel Jaeggli for
their comments and feedbacks.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
7.2. Informative References
[I-D.fear-ippm-mpdm]
Elkins, N., Fioccola, G., and m. mackermann@bcbsm.com,
"IPv6 Marking and Performance and Diagnostic Metrics
(MPDM)", draft-fear-ippm-mpdm-00 (work in progress), June
2018.
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[I-D.krishnan-6man-header-reserved-bits]
Krishnan, S. and J. Halpern, "Reserving bits in the IPv6
header for future use", draft-krishnan-6man-header-
reserved-bits-00 (work in progress), October 2010.
[I-D.krishnan-conex-ipv6]
Krishnan, S., Kuehlewind, M., and C. Ucendo, "Options for
Conex marking in IPv6 packets", draft-krishnan-conex-
ipv6-02 (work in progress), March 2011.
[RFC6294] Hu, Q. and B. Carpenter, "Survey of Proposed Use Cases for
the IPv6 Flow Label", RFC 6294, DOI 10.17487/RFC6294, June
2011, <https://www.rfc-editor.org/info/rfc6294>.
[RFC6436] Amante, S., Carpenter, B., and S. Jiang, "Rationale for
Update to the IPv6 Flow Label Specification", RFC 6436,
DOI 10.17487/RFC6436, November 2011,
<https://www.rfc-editor.org/info/rfc6436>.
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437,
DOI 10.17487/RFC6437, November 2011,
<https://www.rfc-editor.org/info/rfc6437>.
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in
Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
<https://www.rfc-editor.org/info/rfc6438>.
[RFC7837] Krishnan, S., Kuehlewind, M., Briscoe, B., and C. Ralli,
"IPv6 Destination Option for Congestion Exposure (ConEx)",
RFC 7837, DOI 10.17487/RFC7837, May 2016,
<https://www.rfc-editor.org/info/rfc7837>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8250] Elkins, N., Hamilton, R., and M. Ackermann, "IPv6
Performance and Diagnostic Metrics (PDM) Destination
Option", RFC 8250, DOI 10.17487/RFC8250, September 2017,
<https://www.rfc-editor.org/info/rfc8250>.
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[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/info/rfc8321>.
Authors' Addresses
Giuseppe Fioccola
Telecom Italia
Torino
Italy
Email: giuseppe.fioccola@telecomitalia.it
Gunter Van de Velde
Nokia
Antwerp
BE
Email: gunter.van_de_velde@nokia.com
Mauro Cociglio
Telecom Italia
Torino
Italy
Email: mauro.cociglio@telecomitalia.it
Praveen Muley
Nokia
Mountain View
USA
Email: praveen.muley@nokia.com
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