6MAN Working Group G. Fioccola
Internet-Draft T. Zhou
Intended status: Standards Track Huawei
Expires: May 3, 2020 M. Cociglio
Telecom Italia
October 31, 2019
IPv6 Application of the Alternate Marking Method
draft-fz-6man-ipv6-alt-mark-01
Abstract
This document describes how the alternate marking method in [RFC8321]
and [I-D.ietf-ippm-multipoint-alt-mark] can be used as the passive
performance measurement method in an IPv6 domain and reports
implementation considerations. It proposes how to define a new
Extension Header Option to encode alternate marking technique and
also considers the Segment Routing Header TLV alternative.
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
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provisions of BCP 78 and BCP 79.
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Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPv6 application of the Alternate Marking . . . . . . . . . . 3
3. Definition of the AltMark Option/TLV . . . . . . . . . . . . 4
3.1. Data Fields Format . . . . . . . . . . . . . . . . . . . 4
4. AltMark: EH Option or SRH TLV . . . . . . . . . . . . . . . . 5
5. Alternate Marking Method Operation . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe passive
performance measurement method, which can be used to measure packet
loss, latency and jitter on live traffic. Since 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. Consequently, the
SRv6 (Segment Routing over IPv6 data plane) application is also
discussed. Both Extension Header (EH) Option and Segment Routing
Header (SRH) TLV are considered here.
The format of the IPv6 addresses is defined in [RFC4291]. [RFC8200]
introduces the IPv6 Header Format, including the Extension Headers in
the base IPv6 Header and the availability of a 20-bit flow label. In
this respect, [I-D.fioccola-v6ops-ipv6-alt-mark] reported a summary
on the possible implementation options for the application of the
alternate marking method in an IPv6 domain. This document, starting
from the outcome of [I-D.fioccola-v6ops-ipv6-alt-mark], introduces a
new Option/TLV that can be encoded as EH Option or as SRH TLV.
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[I-D.zhou-ippm-enhanced-alternate-marking] defines the data fields
for the alternate marking in order to generalize its application.
More information can be considered within the alternate marking field
to facilitate the efficiency and ease the deployment.
[I-D.song-opsawg-ifit-framework] introduces the telemetry
architecture and [I-D.song-ippm-postcard-based-telemetry] defines the
Postcard-Based Telemetry with Packet Marking (PBT-M). PBT-M marks
the user packets (set one bit) or configure the flow filter to invoke
the data collection. At each PBT-aware node, if the mark is
detected, a postcard is generated and sent to a collector.
2. IPv6 application of the Alternate Marking
The application of the alternate marking requires a marking field.
As mentioned, several alternatives have been analysed in
[I-D.fioccola-v6ops-ipv6-alt-mark] (Extension Header, IPv6 Address,
Flow Label). Anyway the best choice would be the use of an Extension
Header(EH) Option or TLV.
A new Option/TLV can be defined for this scope. This approach
follows [RFC8200] that strongly recommended against creating new EHs
especially with hop by hop behaviour.
The document aims to be general for IPv6 data plane. A possibility
can be to use a Destination or a Hop-By-Hop(HBH) Extension
Header(EH). The assumption is that an EH with an alternate marking
measurement option can be defined. The router processing can be
easily optimized to handle this use case. For SRv6, SRH TLV (as
described in [I-D.ietf-6man-segment-routing-header]) can be a good
choice to encode the Data fields.
The main objective is to ensure enough space to implement and
optimize the deployment of the Alternate Marking method and the
introduction of a monitored flow identification field (FlowMonID), as
described in the next Section goes in this direction. FlowMonID is
also introduced in [I-D.zhou-ippm-enhanced-alternate-marking].
Note that FlowMonID is different from the Flow Label field of the
IPv6 Header ([RFC8200]). Flow Label is used for application service,
like LB/ECMP and QoS. Instead, FlowMonID is only used to identify
the monitored flow. The reuse of flow label field for monitored flow
identification is not considered since it may change the application
intent and forwarding behaviour, so that the measurement does not
align with the original traffic. Furthermore the flow label may be
changed en route and this may also violate the measurement task.
That is to explain the reason why we need to introduce FlowMonID for
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IPv6. Flow Label and FlowMonID within the same packet have different
scope, identify different flows, different usage.
3. Definition of the AltMark Option/TLV
The desired choice is to define a new Extension Header Option/TLV.
[I-D.zhou-ippm-enhanced-alternate-marking] generalizes the data
fields for the alternate marking method and inspired the layout.
3.1. Data Fields Format
The following figure shows the data fields format for enhanced
alternate marking EH Option/TLV. This AltMark data is expected to be
encapsulated to specific encapsulation, e.g. the IPv6 Option or SRH
TLV.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowMonID |L|D|M| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type/Option Type: 8 bit identifier of the type of Option/TLV that
needs to be allocated. Unrecognised Types MUST be ignored on
receipt.
o Length/Opt Data Len: The length of the length Data Fields of this
Option/TLV in bytes.
o FlowMonID: 20 bits unsigned integer. The FlowMon identifier field
is to uniquely identify a monitored flow within the measurement
domain. The field is set at the ingress node. The FlowMonID can
be uniformly assigned by the central controller or algorithmically
generated by the ingress node. The latter approach cannot
guarantee the uniqueness of FlowMonID but it may be preferred for
local or private network, where the conflict probability is small
due to the large FlowMonID space.
o L: Loss flag as defined in [RFC8321];
o D: Delay flag as defined in [RFC8321];
o M: Marking bit as defined in PBT-M
[I-D.song-ippm-postcard-based-telemetry];
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o Reserved: is reserved for further use. These bits MUST be set to
zero.
4. AltMark: EH Option or SRH TLV
Using a new EH Option assumes that all routers in the domain support
this type of headers, but, beyond backward compatibility, the new
AltMark Option Layout seems the best way to implement the Alternate
Marking method.
It is important to highlight that the Option Layout can be used both
as Destination Option and as Hop-By-Hop Option depending on the Use
Cases. In general, it is needed to perform end-to-end or hop-by-hop
measurements, and the alternate marking methodology in [RFC8321]
allows, by definition, both end-to-end and hop-by-hop performance
measurements.
Regarding Hop-By-Hop Options Header, if we consider its real
deployment, it is sometimes dropped by legacy devices and not so used
by intermediate nodes. Destination Options Header is preferred.
SRv6 is a subset of IPv6 and it is one type of routing header. Like
any other use case of IPv6, HBH and Destination options are useable
when SRv6 header is present. Because SRv6 is a routing header,
destination options before the routing header are processed by each
destination in the route list.
SRH TLV can also be a good choice from this point of view. The
intermediated nodes that are not in the SID list can consider the SRH
as a green field, they cannot support and bypass or support and dig
into the SRH TLV.
5. Alternate Marking Method Operation
[RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe in detail
the methodology.
6. Security Considerations
tbc
7. IANA Considerations
The option type should be assigned in IANA's "Destination Options and
Hop-by-Hop Options" registry. Also, the TLV type should be assigned
from Segment Routing Header TLVs Registry.
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8. Acknowledgements
tbc
9. References
9.1. 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>.
9.2. Informative References
[I-D.fioccola-v6ops-ipv6-alt-mark]
Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6
Performance Measurement with Alternate Marking Method",
draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress),
June 2018.
[]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
[I-D.ietf-ippm-multipoint-alt-mark]
Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto,
"Multipoint Alternate Marking method for passive and
hybrid performance monitoring", draft-ietf-ippm-
multipoint-alt-mark-02 (work in progress), July 2019.
[I-D.song-ippm-postcard-based-telemetry]
Song, H., Zhou, T., Li, Z., Shin, J., and K. Lee,
"Postcard-based On-Path Flow Data Telemetry", draft-song-
ippm-postcard-based-telemetry-06 (work in progress),
October 2019.
[I-D.song-opsawg-ifit-framework]
Song, H., Li, Z., Zhou, T., Qin, F., Chen, H., Jin, J.,
and J. Shin, "In-situ Flow Information Telemetry", draft-
song-opsawg-ifit-framework-06 (work in progress), October
2019.
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[I-D.zhou-ippm-enhanced-alternate-marking]
Zhou, T., Fioccola, G., Li, Z., Lee, S., Cociglio, M., and
Z. Li, "Enhanced Alternate Marking Method", draft-zhou-
ippm-enhanced-alternate-marking-03 (work in progress),
July 2019.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[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>.
[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
Huawei
Riesstrasse, 25
Munich 80992
Germany
Email: giuseppe.fioccola@huawei.com
Tianran Zhou
Huawei
156 Beiqing Rd.
Beijing 100095
China
Email: zhoutianran@huawei.com
Mauro Cociglio
Telecom Italia
Via Reiss Romoli, 274
Torino 10148
Italy
Email: mauro.cociglio@telecomitalia.it
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