MPLS Working Group W. Cheng
Internet-Draft China Mobile
Intended status: Standards Track X. Min
Expires: January 8, 2020 ZTE
T. Zhou
Huawei
X. Dong
FiberHome
Y. Peleg
Broadcom
July 7, 2019
Encapsulation For MPLS Performance Measurement with Alternate Marking
Method
draft-cheng-mpls-inband-pm-encapsulation-01
Abstract
This document defines the encapsulation for MPLS performance
measurement with alternate marking method, which performs flow-based
packet loss, delay, and jitter measurements on live traffic.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions Used in This Document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Flow-based PM Encapsulation in MPLS . . . . . . . . . . . . . 3
2.1. Examples for Applying Flow-ID in a label stack . . . . . 4
3. Procedures of Encapsulation, Look-up and Decapsulation . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
[I-D.fioccola-spring-flow-label-alt-mark] describes how the alternate
marking method can be used as the passive performance measurement
method in an IPv6 domain, actually the alternate marking method can
also be applied to an MPLS domain, and what's missed is the
encapsulation for MPLS performance measurement with alternate marking
method.
[RFC8372] discusses the desired capabilities for MPLS flow
identification, in order to perform a better in-band performance
monitoring of user data packets. Synonymous Flow Label (SFL), which
is introduced in [I-D.ietf-mpls-sfl-framework], is identified as a
method of accomplishing MPLS flow identification. This document
employs a method, other than SFL, to accomplish MPLS flow
identification. The method described in this document is simple and
flexible, furthermore, it complies with the current MPLS forwarding
paradigm.
This document defines the encapsulation for MPLS performance
measurement with alternate marking method, which performs flow-based
packet loss, delay, and jitter measurements on live traffic.
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1.1. Conventions Used in This Document
1.1.1. Terminology
LSP: Label Switched Path
MPLS: Multi-Protocol Label Switching
NMS: Network Management System
PM: Performance Measurement
PW: PseudoWire
SFL: Synonymous Flow Label
TC: Traffic Class
TTL: Time to Live
VC: Virtual Channel
VPN: Virtual Private Network
1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Flow-based PM Encapsulation in MPLS
Flow-based MPLS performance measurement encapsulation with alternate
marking method has the following format:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow-ID Indicator Label (TBA1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow-ID |L|D|R|S| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Payload ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Flow-based PM Encapsulation in MPLS
Where Flow-ID Indicator Label is defined in this document as value
TBA1, and the other fields related to the Flow-based PM encapsulation
are defined as follows:
o Flow-ID - an MPLS label value used as MPLS flow identification
[RFC8372], it should be unique within the administrative domain.
Flow-ID values can be allocated by an external NMS or a
controller, based on measurement object instance such as LSP and
PW. There is a one-to-one mapping between Flow-ID and flow. The
specific method on how to allocate the Flow-ID values is outside
the scope of this draft. Note that the Flow-ID Label can be
placed either at the bottom of the MPLS label stack or not, and
the Flow-ID Indicator Label MAY appear multiple times in a label
stack, which means more than one Flow-ID can be present within an
MPLS label stack. Section 2.1 of this document provides several
examples to illustrate how to apply Flow-ID in a label stack.
o L and D - L(oss) bit and D(elay) bit are used for coloring the
packets (called double-marking methodology), which is required by
the alternate marking method.
o R - R bit is reserved for future use and MUST be set to zero.
o Reserved - one octet long field reserved for future use and MUST
be set to zero.
2.1. Examples for Applying Flow-ID in a label stack
Three examples on different layout of Flow-ID label (4 octets) are
illustrated as follows:
(1) Layout of Flow-ID label when applied to MPLS LSP.
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+----------------------+
| |
| LSP |
| Label |
+----------------------+
| |
| Flow-ID Indicator |
| Label |
+----------------------+
| |
| Flow-ID |
| Label |
+----------------------+
| |
| VPN |
| Label |
+----------------------+ <= Bottom of stack
| |
| Payload |
| |
+----------------------+
Figure 2: Applying Flow-ID to MPLS LSP
(2) Layout of Flow-ID label when applied to MPLS VPN traffic.
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+----------------------+
| |
| LSP |
| Label |
+----------------------+
| |
| VPN |
| Label |
+----------------------+
| |
| Flow-ID Indicator |
| Label |
+----------------------+
| |
| Flow-ID |
| Label |
+----------------------+ <= Bottom of stack
| |
| Payload |
| |
+----------------------+
Figure 3: Applying Flow-ID to MPLS VPN
(3) Layout of Flow-ID label when applied to both MPLS LSP and MPLS
VPN traffic.
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+----------------------+
| |
| LSP |
| Label |
+----------------------+
| |
| Flow-ID Indicator |
| Label |
+----------------------+
| |
| Flow-ID |
| Label |
+----------------------+
| |
| VPN |
| Label |
+----------------------+
| |
| Flow-ID Indicator |
| Label |
+----------------------+
| |
| Flow-ID |
| Label |
+----------------------+ <= Bottom of stack
| |
| Payload |
| |
+----------------------+
Figure 4: Applying Flow-ID to both MPLS LSP and MPLS VPN
Note that here VPN label can be MPLS PW label, MPLS Ethernet VPN
label or MPLS IP VPN label, and it's also called VC label as defined
in [RFC4026].
Also note that for this example the two Flow-ID values appearing in a
label stack MUST be different, that is to say, Flow-ID applied to
MPLS LSP and Flow-ID applied to MPLS VPN share the same value space.
3. Procedures of Encapsulation, Look-up and Decapsulation
The procedures for Flow-ID label encapsulation, look-up and
decapsulation are summarized as follows:
o The ingress node inserts the Flow-ID Indicator Label, alongside
with the Flow-ID label, into the MPLS label stack. At the same
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time, the ingress node sets the L bit and D bit, as needed by
alternate-marking technique, and sets the Flow-ID value, as
defined in this document.
o The transit nodes look up the Flow-ID label with the help of the
Flow-ID Indicator Label, and transmit the collected information to
an external NMS or a controller, which includes the values of the
block counters and the timestamps of the marked packets, along
with the value of the Flow-ID, referring to the procedures of
alternate marking method.
o The egress node pops the Flow-ID Indicator Label, alongside with
the Flow-ID label, from the MPLS label stack. This document
doesn't introduce any new procedure regarding to the process of
the decapsulated packet.
4. Security Considerations
This document does not introduce additional security requirements and
mechanisms.
5. IANA Considerations
In the Special-Purpose MPLS Label Values registry defined in
[SP-MPLS-Label], a new Special-Purpose MPLS Label Value for Flow-ID
Indicator is requested from IANA as follows:
+---------------------+-----------------+---------------+-----------+
| Special-Purpose | Description | Semantics | Reference |
| MPLS Label Value | | Definition | |
+---------------------+-----------------+---------------+-----------+
| TBA1 | Flow-ID | Section 2 | This |
| | Indicator Label | | Document |
+---------------------+-----------------+---------------+-----------+
Table 1: New Special-Purpose MPLS Label Value for Flow-ID Indicator
6. Acknowledgements
The authors would like to acknowledge Greg Mirsky, Aihua Liu,
Shuangping Zhan and Ming Ke for their careful review and very helpful
comments.
7. References
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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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[SP-MPLS-Label]
"Special-Purpose MPLS Label Values", 2014,
<https://www.iana.org/assignments/mpls-label-values/
mpls-label-values.xml>.
7.2. Informative References
[I-D.fioccola-spring-flow-label-alt-mark]
Fioccola, G., Velde, G., Cociglio, M., and P. Muley,
"Using the IPv6 Flow Label for Performance Measurement
with Alternate Marking Method in Segment Routing", draft-
fioccola-spring-flow-label-alt-mark-01 (work in progress),
October 2017.
[I-D.ietf-mpls-sfl-framework]
Bryant, S., Chen, M., Li, Z., Swallow, G., Sivabalan, S.,
and G. Mirsky, "Synonymous Flow Label Framework", draft-
ietf-mpls-sfl-framework-04 (work in progress), December
2018.
[RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual
Private Network (VPN) Terminology", RFC 4026,
DOI 10.17487/RFC4026, March 2005,
<https://www.rfc-editor.org/info/rfc4026>.
[RFC8372] Bryant, S., Pignataro, C., Chen, M., Li, Z., and G.
Mirsky, "MPLS Flow Identification Considerations",
RFC 8372, DOI 10.17487/RFC8372, May 2018,
<https://www.rfc-editor.org/info/rfc8372>.
Authors' Addresses
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Weiqiang Cheng
China Mobile
Beijing
China
Email: chengweiqiang@chinamobile.com
Xiao Min
ZTE
Nanjing
China
Email: xiao.min2@zte.com.cn
Tianran Zhou
Huawei
Beijing
China
Email: zhoutianran@huawei.com
Ximing Dong
FiberHome
Wuhan
China
Email: dxm@fiberhome.com
Yoav Peleg
Broadcom
USA
Email: yoav.peleg@broadcom.com
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