wdiff rfc8592.original rfc8592.txt

Network Working Group
Independent Submission R. Browne
Internet Draft
Request for Comments: 8592 A. Chilikin
Intended status:
Category: Informational Intel
Expires: August 2019
ISSN: 2070-1721 T. Mizrahi
Huawei Network.IO Innovation Lab
February 25,
May 2019

Key Performance Indicators Indicator (KPI) Stamping
for the Network Service Header (NSH)
draft-browne-sfc-nsh-kpi-stamp-07

Abstract

This document describes a method methods of carrying Key Performance
Indicators (KPIs) using the Network Service Header (NSH). This method These
methods may be used, for example, to monitor latency and QoS marking
to identify problems on some links or service functions.

Status of this This Memo

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Table of Contents

1. Introduction ................................................ 2 ....................................................2
2. Terminology ................................................. 3 .....................................................3
2.1. Requirement Requirements Language ................................... 3 ......................................3
2.2. Definition of Terms .................................... 3 ........................................3
2.2.1. Terms Defined in this This Document .................... 4 ......................4
2.3. Abbreviations .......................................... 4 ..............................................5
3. NSH KPI Stamping: An Overview ............................... 6 ...................................6
3.1. Prerequisites .......................................... 7 ..............................................7
3.2. Operation ............................................. 10 ..................................................9
3.2.1. Flow Selection ................................... 10 ......................................9
3.2.2. SCP Interface .................................... 10 ......................................10
3.3. Performance Considerations ............................ 11 ................................11
4. NSH KPI-stamping KPI-Stamping Encapsulation ............................. 12 .................................12
4.1. KPI-stamping KPI-Stamping Extended Encapsulation ................... 13 .......................13
4.1.1. NSH Timestamping Encapsulation (Extended Mode) ... 15 .....15
4.1.2. NSH QoS-stamping QoS-Stamping Encapsulation (Extended Mode) ... 17 .....17
4.2. KPI-stamping KPI-Stamping Encapsulation (Detection Mode) ........... 20 ...............20
5. Hybrid Models .............................................. 22 ..................................................22
5.1. Targeted VNF Stamp .................................... 23 Stamping .....................................23
6. Fragmentation Considerations ............................... 23 ...................................23
7. Security Considerations .................................... 24 ........................................24
8. IANA Considerations ........................................ 25 ............................................24
9. Contributors ............................................... 25
10. Acknowledgments ........................................... 25
11. References ................................................ 25
11.1. .....................................................25
9.1. Normative References ................................. 25
11.2. ......................................25
9.2. Informative References ............................... 26 ....................................25
Acknowledgments ...................................................27
Contributors ......................................................27
Authors' Addresses ................................................27

1. Introduction

The Network Service Header (NSH), as defined by [RFC8300], specifies
a method for steering the traffic among an ordered set of Service
Functions (SFs) using an extensible service header. This allows for
flexibility and programmability in the forwarding plane to invoke the
appropriate SFs for specific flows.

The NSH promises a compelling vista of operational flexibility.
However, many service providers are concerned about service and
configuration visibility. This concern increases when considering
that many service providers wish to run their networks seamlessly in 'hybrid' mode,
"hybrid mode", whereby they wish to mix physical and virtual SFs and
run services seamlessly between the two domains.

This document describes generic methods to monitor and debug service
function chains Service
Function Chains (SFCs) in terms of latency and QoS marking of the
flows within a service function chain. This is refered an SFC. These are referred to detection mode as "detection mode" and extended mode
"extended mode" and are explained in section Section 4.

The method methods described in the this document is are compliant with hybrid
architectures in which Virtual Network Functions (VNFs) and Physical
Network Functions (PNFs) are freely mixed in the service function
chain. This method SFC. These methods
also provides provide flexibility to monitor for monitoring the performance and
configuration of an entire chain or part parts thereof as desired. This method is These
methods are extensible to monitoring other KPIs. Key Performance Indicators
(KPIs). Please refer to [RFC7665] for an architectural context for
this document.

The method methods described in this document is are not an OAM protocol Operations,
Administration, and Maintenance (OAM) protocols such as
[Y.1731] or [Y.1564]. [Y.1731]. As such it does
such, they do not define new OAM packet types or operation. Rather it monitors operations. Rather,
they monitor the service function chain SFC's performance and configuration for subscriber
payloads and indicates indicate subscriber QoE rather than out-of-band
infrastructure metrics. This document differs from to [I-D.ippm.ioam] [In-Situ-OAM] in
the sense that it is specifically tied to NSH operation operations and is not
generic in nature.

2. Terminology

2.1. Requirement 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] [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

2.2. Definition of Terms

This section presents the main terms used in this document. This
document also makes use of the terms defined in [RFC7665] and
[RFC8300].

2.2.1. Terms Defined in this This Document

First Stamping Node (FSN): The first node along a service function
chain an SFC that stamps
packets using KPI stamping. The FSN matches each packet with a
Stamping Controller (SC) flow based on (but not limited to) a
stamping classification criterion such as transport 5-tuple coordinates, but
not limited to.
coordinates.

Last Stamping Node (LSN): The last node along a service function
chain an SFC that stamps
packets using KPI stamping. From a forwarding point of view view, the
LSN removes the NSH header and forwards the raw IP packet to the next
hop. From a control plane control-plane point of view view, the LSN reads all the
metadata (MD) and exports it to a system performance statistics
agent or repository. The LSN should use the NSH Service Index
(SI) to indicate if a an SF was at the end of the chain. The LSN
may change the Service Path Identifier (SPI) to a preconfigured
value in order so that the network underlay forwards the metadata MD back directly
to the KPI database (KPIDB) based on this value.

Key Performance Indicator Database (KPIDB): denotes Denotes the external
storage of metadata MD for reporting, trend analysis, etc.

KPI-stamping:

KPI stamping: The insertion of latency-related and/or QoS-related
information into a packet using NSH metadata. MD.

Flow ID: The Flow ID is a A unique 16 bit 16-bit identifier written into the header by the
classifier. This allows 65536 flows to be concurrently stamped on
any given NSH service chain (SPI).

QoS-stamping: chain.

QoS stamping: The insertion of QoS-related information into a packet
using NSH metadata. MD.

Stamping Controller (SC): The SC is the central logic that decides what
packets to stamp and how. how to stamp them. The SC instructs the
classifier on how to build the KPI stamp specific parts of the NSH.

Stamp NSH that are specific
to KPI stamping.

Stamping Control Plane (SCP): the The control plane between the FSN and
the SC.

2.3. Abbreviations

DEI Drop Eligible Indicator

DSCP Differentiated Services Code Point

FSN First Stamping Node

KPI Key Performance Indicator

KPIDB Key Performance Indicator Database

LSN Last Stamping Node

MD Metadata

NFV Network Function Virtualization

NFVI-PoP NFV Infrastructure Point of Presence

NIC Network Interface Card

NSH Network Service Header

OAM Operations, Administration, and Maintenance

PCP Priority Code Point

PNF Physical Network Function

PNFN Physical Network Function Node

QoE Quality of Experience

QoS Quality of Service

QS QoS Stamp

RSP Rendered Service Path

SC Stamping Controller

SCL Service Classifier

SCP Stamp Stamping Control Plane

SI Service Index

SF Service Function

SFC Service Function Chain

SFP

SI Service Function Path Index

SSI Stamp Service Index
TC Traffic Class
TS Timestamp

VLAN Virtual Local Area Network

VNF Virtual Network Function

vSwitch Virtual Switch

3. NSH KPI Stamping: An Overview

A typical KPI stamping KPI-stamping architecture is presented in Figure 1.

Stamping
Controller
| KPIDB
| SCP Interface |
,---. ,---. ,---. ,---.
/ \ / \ / \ / \
( SCL )-------->( SF1 )--------->( SF2 )--------->( SFn )
\ FSN / \ / \ / \ LSN /
`---' `---' `---' `---'

Figure 1: Logical roles Roles in NSH KPI Stamping

The Stamping Controller (SC) SC will be part of the SFC control plane control-plane architecture, but it is
described separately in this document for clarity.

The SC is responsible for initiating start/stop stamp requests to the
SCL or First Stamp Node (FSN), FSN and also for distributing NSH stamping the NSH-stamping policy into the
service chain via the Stamping Control Plane (SCP) SCP interface.

The FSN will typically be part of the SCL, SCL but again is called out as a
separate logical entity for clarity.

The FSN is responsible for marking NSH MD fields which fields; this tells nodes in
the service chain how to behave in terms of stamping at the SF
ingress,
egress the SF egress, or both, or ignoring the stamp NSH metadata MD
completely.

The FSN also writes the Reference Time value, a (possibly inaccurate)
estimate of the current time-of-day, time of day, into the header, allowing the
{SPI:Flow ID}
"SPI:Flow ID" performance to be compared to previous samples for
offline analysis.

The FSN should return an error to the SC if not synchronized to the
current time-of-day time of day and forward the packet along the service-chain service chain
unchanged. The code and format of the error is are specific to the
protocol used between the FSN and SC; these considerations are out of
scope.

SF1 and SF2 stamp the packets as dictated by the FSN and process the
payload as per normal.

Note 1: The exact location of the stamp creation may not be in the SF itself,
itself and may be applied by a hardware device -- for
example, as discussed in Section 3.3.

Note 2: Special cases exist where some of the SFs are
NSH-unaware. NSH unaware.
This is covered in Section 5.

The Last Stamp Node (LSN) LSN should strip the entire NSH header and forward the raw packet to the
IP next hop as per [RFC8300]. The LSN also exports NSH stamp NSH-stamping
information to the KPI Database (KPIDB) KPIDB for offline analysis; the LSN may either export the
stamping information of either (1) all packets, packets or (2) a subset based
on packet sampling.

In fully virtualized environments environments, the LSN is likely to be co-located
with the SF that decrements the NSH Service Index (SI) SI to zero. Corner cases exist whereby
where this is not the case and is covered in case; see Section 5.

3.1. Prerequisites

Timestamping presents a has its own set of prerequisites; however, these
prerequisites are not required to QoS-
Stamp. for QoS stamping. In order to
guarantee metadata MD accuracy, all servers hosting VNFs should be
synchronized from a centralized stable clock. As it is assumed that
PNFs do not timestamp (as this would involve a software change and a
probable impact on throughput performance impact) performance), there is no need for them
to synchronize. There are two possible levels of synchronization:

Level A: Low accuracy Low-accuracy time-of-day synchronization, based on NTP
[RFC5905].

Level B: High accuracy High-accuracy synchronization (typically on the order of
microseconds), based on [IEEE1588].

Each SF SHOULD have a level Level A synchronization, synchronization and MAY have a level Level B
synchronization.

Level A requires each platform (including the Stamp Controller) SC) to synchronize its
system real-time-clock real-time clock to an NTP server. This is used to mark the metadata MD
in the chain, using the <Reference Time> Reference Time field in the NSH KPI-stamp KPI stamp
header (Section 4.2). 4.1). This timestamp is inserted
to into the NSH by the
first SF in the chain. NTP accuracy can vary by several milliseconds
between locations. This is not an issue issue, as the Reference Time is
merely being used as a time-of-day reference inserted into the KPIDB
for performance monitoring and metadata MD retrieval.

Level B synchronization requires each platform to be synchronized to
a Primary Reference Time Clock (PRTC) (PRC) using the Precision Time Protocol
(PTP) [IEEE1588]. A platform MAY also use Synchronous Ethernet
([G.8261], [G.8262], [G.8264]),
[G.8261] [G.8262] [G.8264], allowing more accurate frequency
synchronization.

If an SF is not synchronized at the moment of timestamping, it should
indicate its synchronization status in the NSH. This is described in
more detail in Section 4.

By synchronizing the network in this way, the timestamping operation
is independent of the current Rendered Service Path (RSP). Indeed RSP. Indeed, the timestamp metadata MD can
indicate where a chain has been moved due to a resource starvation
event as indicated in Figure 2, between VNF 3 VNF3 and
VNF 4 VNF4 at time B.

Delay
| v
| v
| x
| x x = reference time Reference Time A
| xv v = reference time Reference Time B
| xv
| xv
|______|______|______|______|______|_____
VNF1 VNF2 VNF3 VNF4 VNF5

Figure 2: Flow performance Performance in a service chain Service Chain

For QoS-stamping QoS stamping, it is desired that the SCL or FSN be synchronized
in order to provide reference time a Reference Time for offline analysis, but this
is not a hard requirement (they may be in holdover or free-run state,
for example). Other SFs in the service chain do not need to be
synchronized for QoS-stamping operation operations, as described below.

QoS-stamping

QoS stamping can be used to check the consistency of configuration
across the entire chain or part parts thereof. By adding all potential layer
Layer 2 and
layer Layer 3 QoS fields into a QoS sum at the SF ingress or
egress, this allows quick identification of QoS mismatches across
multiple L2/L3
fields Layer 2 / Layer 3 fields, which otherwise is a manual,
expert-led consuming process.

|
|
| xy
| xy x = ingress QoS sum
| xv v = egress QoS sum
| xv y = egress QoS sum miss mismatch
| xv
|______|______|______|______|______|_____
SF1 SF2 SF3 SF4 SF5

Figure 3: Flow QoS Consistency in a service chain Service Chain

Referring to Figure 3, x, v, and y are notional sum values of the QoS
marking configuration of the flow within a given chain. As the
encapsulation of the flow can change from hop to hop in terms of VLAN
header(s), MPLS labels, DSCP(s) or DSCP(s), these values are used to compare
the consistency of configuration from from, for example example, payload DSCP
through overlay and underlay QoS settings in VLAN IEEE 802.1Q bits,
MPLS bits bits, and infrastructure DSCPs.

Figure 3 indicates that that, at SF4 in the chain, the egress QoS marking
is inconsistent. That is, the ingress QoS settings do not match the
egress. The method described here will indicate which QoS field(s)
is
inconsistent, inconsistent and whether this is ingress (whereby (where the underlay has
incorrectly marked and queued the packet) or egress (where the SF has
incorrectly marked and queued the packet.

Note that the SC must be aware of cases when a an SF remarks re-marks QoS
fields deliberately and thus does not flag an issue for desired
behavior.

3.2. Operation

KPI-stamping detection mode uses MD type Type 2 as defined in [RFC8300].
This involves the SFC classifier stamping the flow at the chain ingress,
ingress and no subsequent stamps being applied, rather applied; rather, each SF upstream
SF can compare its local condition with the ingress value and take
appropriate action. Therefore Therefore, detection mode is very efficient in
terms of header size that does not grow after the classification.
This is further explained in Section 4.1. 4.2.

3.2.1. Flow Selection

The SC should maintain a list of flows within each service chain to
be monitored. This flow table should be in the format 'SPI:FlowID'. "SPI:Flow ID".
The SC should map these pairs to unique values presented as Flow IDs
per service chain within the NSH TLV specified in this document. document (see
Section 4). The SC should instruct the FSN to initiate timestamping
on flow table match. The SC may also tell the classifier the
duration of the timestamping operation, either by a either the number of
packets in the flow or
by a certain time duration.

In this way way, the system can monitor the performance of the all en-
route en-route
traffic, or an individual subscriber in a chain, or just a specific
application or a QoS class that is used in the network.

The SC should write the list of monitored flows into the KPIDB for
correlation of performance and configuration data. Thus, when the
KPIDB receives data from the LSN LSN, it understands to which flow the
data pertains.

The association of a source IP to address with a subscriber identity is
outside the scope of this document and will vary by network
application. For example, the method of association of a source IP to IMSI
address with an International Mobile Subscriber Identity (IMSI) will
be different to from how a CPE Customer Premises Equipment (CPE) entity with NAT
a Network Address Translation (NAT) function may be chained in an
enterprise NFV application.

3.2.2. SCP Interface

A Stamp Control Plane (SCP)

An SCP interface is required between the SC and the FSN or
classifier. This interface is used to:

o Query the SFC classifier for a list of active chains and flows.

o Communicate which chains and flows to stamp. This can be a
specific {SPI:Flow ID} "SPI:Flow ID" combination or can include wildcards for
monitoring subscribers across multiple chains or multiple flows
within one chain.

o Instruct how the stamp should be applied (ingress, egress, both
ingress and egress, or specific).

o Indicate when to stop stamping, stamping (after either after a certain number of
packets or duration.

Typically a certain time duration).

Typically, SCP timestamps flows for a certain duration for trend
analysis,
analysis but only stamps one packet of each QoS class in a chain
periodically (perhaps once per day or after a network change).
Therefore, timestamping is generally applied to a much larger set of
packets than QoS-stamping.

Exact QoS stamping.

The exact specification of SCP is left for further study.

3.3. Performance Considerations

This document does not mandate a specific stamping implementation
method, and thus
method; thus, NSH KPI stamping can either be performed by either hardware
mechanisms,
mechanisms or by software.

If software-based stamping is used, applying and operating on the
stamps themselves incur an additional small delay in the service
chain. However, it can be assumed that these additional delays are
all relative for the flow in question. This is only pertinent for
timestamping mode, and not for QoS-stamping mode. Thus, whilst the
absolute timestamps may not be fully accurate for normal non-
timestamped traffic
non-timestamped traffic, they can be assumed to be relative.

It is assumed that the method methods described in this document would only
operate on a small percentage of user flows.

The service provider may choose a flexible policy in the SC to
timestamp a selection of user-plane a user plane every minute -- for example example, to
highlight any performance issues. Alternatively, the LSN may
selectively export a subset of the KPI-stamps KPI stamps it receives, based on a
predefined sampling method. Of course course, the SC can stress test stress-test an
individual flow or chain should a deeper analysis be required. We
can expect that this type of deep analysis has will have an impact on the
performance of the chain itself whilst under investigation. The This
impact will be dependent on vendor implementation implementations and is outside the
scope of this document.

For QoS-stamping QoS stamping, the method methods described here is are even less intrusive,
as typically multiple packets in a flow are only QoS stamped periodically (perhaps once
per day) to check one packet in a service chain configuration per QoS class.

4. NSH KPI-stamping KPI-Stamping Encapsulation

KPI stamping uses NSH MD type Type 0x2 for detection of anomalies and
extended mode for root cause root-cause analysis of KPI violations. These are
further explained in this section.

The generic NSH MD type Type 2 TLV for KPI Stamping stamping is shown below.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|U| TTL | Length |U|U|U|U|Type=2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable-length Variable Length KPI Metadata header and TLV(s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4: Generic NSH KPI Encapsulation

Relevant fields in the header that the FSN must implement: implement are as
follows:

o The O bit must not be set.

o The MD type must be set to 0x2 0x2.

o The Metadata Class must be set to a value from the experimental
range 0xfff6 to 0xfffe according to an agreement by all parties to
the experiment.

o Unassigned bits: all fields, All fields marked U, "U" are unassigned and
available for future use [RFC8300] [RFC8300].

o The Type field may have one of the following values; the content
of "KPI metadata" the Variable Length KPI Metadata header and TLV(s) field
depends on the type Type value:

* Type = 0x01 Det: (Det): Detection

* Type = 0x02 TS: (TS): Timestamp Extended

* Type = 0x03 QoS: QoS-stamp (QoS): QoS stamp Extended

The Type field determines the type of KPI-stamping format. The
supported formats are presented in the following subsections.

4.1. KPI-stamping KPI-Stamping Extended Encapsulation

The generic NSH MD type Type 2 KPI-stamping header extended mode (extended mode) is
shown in Figure 5. This is the format for performance monitoring of
service chain issues with respect to QoS configuration and latency.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|U| TTL | Length |U|U|U|U|Type=2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length KPI Configuration Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length KPI Value (LSN) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length KPI Value (FSN) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 5: Generic KPI Encapsulation (Extended Mode)

As mentioned above, two types are defined under the experimental MD
class to indicate the extended KPI MD: a timestamp type and a
QoS-stamp type.

The KPI Encapsulation Configuration Header format is shown below.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|K|K|T|K|K|K|K|K| Stamping SI | Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reference Time |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 6: KPI Encapsulation Configuration Header
The bits marked as 'K' "K" are reserved for specific KPI type use and are
described in the corresponding subsections below.

The T bit should be set if Reference Time follows the KPI
Encapsulation Configuration Header.

Stamping Service Index

The SSI (Stamping SI) contains the Service Index SI used for KPI stamping and is
described in the corresponding subsections below.

The Flow ID is a unique 16 bit 16-bit identifier written into the header by
the classifier. This allows 65536 flows to be concurrently stamped
on any given NSH service chain (SPI). Flow IDs are not written by
subsequent SFs in the chain. The FSN may export monitored flow Flow IDs
to the KPIDB for correlation.

Reference Time is the wall clock of the FSN, FSN and may be used for
historical comparison of SC performance. If the FSN is not Level A
synchronized (see Section 3.1) 3.1), it should inform the SC over the SCP
interface. The Reference Time is represented in 64-bit NTP format
[RFC5905]
[RFC5905], as presented in Figure 7:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 7: NTP [RFC5905] 64-bit 64-Bit Timestamp Format (RFC 5905)

4.1.1. NSH Timestamping Encapsulation (Extended Mode)

The NSH timestamping extended encapsulation is shown below.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|U|U|U|U|U|U| Length |U|U|U|U|Type=2 | NextProto |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type=TS(2) |U| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|E|T|U|U|U|SSI| Stamping SI | Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Reference Time (T bit is set) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|E|U|U|U| SYN | Stamping SI | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Ingress Timestamp (I bit is set)(LSN) set) (LSN) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Timestamp (E bit is set)(LSN) set) (LSN) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|E|U|U|U| SYN | Stamping SI | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Ingress Timestamp (I bit is set) (FSN) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Timestamp (E bit is set) (FSN) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 8: NSH Timestamp Encapsulation (Extended Mode)

The FSN KPI-stamp metadata KPI stamp MD starts with the Stamping Configuration Header.
This header contains the I, E, and T bits bits, and Stamp Service Index (SSI). the SSI.

The I bit should be set if the Ingress stamp is requested.

The E bit should be set if the Egress stamp is requested.

The SSI field must be set to one of the following values:

o 0x0 KPI-stamp mode, no Service index 0x0: KPI stamp mode. No SI is specified in the Stamp
Service Index Stamping SI field.

o 0x1 KPI-stamp Hybrid 0x1: KPI stamp hybrid mode is selected, Stamp Service Index selected. The Stamping SI field
contains the LSN Service index. SI. This is used when PNFs or NSH-unaware SFs
are used at the tail of the chain. If SSI=0x1, then the value in
the type Type field informs the chain regarding which SF should act as
the LSN.

o 0x2 KPI-stamp 0x2: KPI stamp Specific mode is selected, Stamp Service Index selected. The Stamping SI field
contains the targeted Service Index. SI. In this case case, the Stamp
Service Index Stamping SI field
indicates which SF is to be stamped. Both
ingress Ingress stamps and egress
Egress stamps are performed when the SI=SSI on in the chain. For
timestamping mode, the FSN will also apply the Reference Time and
Ingress Timestamp. This will indicate the delay along the entire
service chain to the targeted SF. This method may also be used as
a light implementation to monitor end-to-end service chain
performance whereby the targeted SF is the LSN. This is not
applicable to QoSStamping QoS-stamping mode.

Each stamping Node node adds stamping metadata which consist stamp MD that consists of the Stamping
Reporting Header and timestamps.

The E bit should be set if the Egress stamp is reported.

The I bit should be set if the Ingress stamp is reported.

With respect to timestamping mode, the SYN bits are an indication of
the synchronization status of the node performing the timestamp and
must be set to one of the following values:

o In Synch: synch: 0x00

o In holdover: 0x01

o In free run: 0x02

o Out of Synch: synch: 0x03

If the platform hosting the SF is out of synch or in free run run, no
timestamp is applied by the node node, and the packet is processed
normally.

If the FSN is out of synch or in free run run, the timestamp request is
rejected and is not propagated though through the chain. The In such an event,
the FSN should inform the SC in such
an event over the SCP interface. Similarly Similarly, if
the KPIDB receives timestamps that are out of order (i.e. (i.e., a time stamp
timestamp of a 'N+1' an "N+1" SF is
in prior to the past timestamp of a 'N' SF) an "N" SF), it
should notify the SC of this condition over the SCP interface.

The outer service index SI value is copied into the stamp metadata MD as the Stamping SI to
help cater for to hybrid chains that are a mix of VNFs and PNFs or
through NSH-unaware SFs. Thus, if a flow transits through a PNF or
an NSH-unaware node node, the delta in the inner service index SI between timestamps
will indicate this.

The Ingress Timestamp and Egress Timestamp are represented in 64-bit
NTP format. The corresponding bits (I and E) are reported in the
Stamping Reporting Header of the node's metadata. MD.

4.1.2. NSH QoS-stamping QoS-Stamping Encapsulation (Extended Mode)

Packets have a variable QoS stack. That is for example For example, the same payload IP
can have a very different stack in the access part of the network to
than the core. This is most apparent in mobile networks where where, for example
example, in an access circuit we would have 2 layers of an infrastructure IP
header (DSCP) - composed of two layers -- one transport-based based on transport and
the other
IPsec-based, based on IPsec -- in addition to multiple MPLS and VLAN
tags. The same
packet packet, as it leaves the PDN Packet Data Network (PDN)
Gateway Gi egress interface interface, may be very much simplified in terms of
overhead and related QoS fields.

Because of this variability variability, we need to build extra meaning into the
QoS headers - they headers. They are not not, for example example, all PTP timestamps of a
fixed
length length, as in the case of timestamping, rather timestamping; rather, they are of
variable lengths and types. Also Also, they can be changed on the
underlay at any time without the knowledge by of the SFC system. Therefore
Therefore, each SF must be able to ascertain and record its ingress
and egress QoS configuration on the fly.

The suggested QoS type, Type (QT) and lengths are as listed below. The type is 4 bits
long.

QoS Type(QT)Value Type Value Length Comment
----------------------------------------------------------
IVLAN 0x01 4 Bits Ingress VLAN (PCP + DEI)

EVLAN 0x02 4 Bits Egress VLAN

IQINQ 0x03 8 Bits Ingress QinQ (2x PCP+DEI) (PCP + DEI))

EQINQ 0x04 8 Bits Egress QinQ

IMPLS 0x05 3 Bits Ingress Label

EMPLS 0x06 3 Bits Egress Label

IMPLS 0x07 6 Bits 2 Two Ingress Labels (2x EXP)

EMPLS 0x08 6 Bits 2 Two Egress Labels

IDSCP 0x09 8 Bits Ingress DSCP

EDSCP 0x0A 8 Bits Egress DSCP

For stacked headers such as MPLS and 802.1ad, we extract the QoS relevant
QoS data from the header and insert it into one QoS value in order to
be more efficient on in terms of packet size. Thus Thus, for MPLS, we
represent both EXP experimental bits (EXP) fields in one QoS value, and
both 802.1p priority and drop precedence in one QoS value value, as
indicated above.

For stack types not listed here, for here (for example, 3 three or more MPLS tags,
tags), the SF would insert IMPLS/EMPLS several times times, with each layer
in the stack indicating EXP Qos QoS for that layer.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|U|U|U|U|U|U| Length |U|U|U|U|Type=2 | NextProto=0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type=QoS(3) |U| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|U|T|U|U|U|SSI| Stamping SI | Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Reference Time (T bit is set) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|U|U|U|U|U|U|U| Stamping SI | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| QT | QoS Value |U|U|U|E| QT | QoS Value |U|U|U|E|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|U|U|U|U|U|U|U| Stamping SI | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| QT | QoS Value |U|U|U|E| QT | QoS Value |U|U|U|E|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 9: NSH QoS Configuration Encapsulation (Extended Mode)

The encapsulation in Figure 10 9 is very similar to that the encapsulation
detailed in Section 4.1 4.1.1, with the following exceptions:

o I and E bits are not required required, as we wish to examine the full QoS
stack at the ingress and egress at every SF.

- Syn

o SYN status bits are not required.

o The QT (QoS Type) and QoS value values are as outlined in the table list above.

o The E bit at the tail of each QoS context field indicates if this
is the last egress QoS-stamp QoS stamp for a given SF. This should coincide
with SI=0 at the LSN, whereby the packet is truncated and truncated, the NSH MD
is sent to the KPIDB KPIDB, and the subscriber subscriber's raw IP packet is
forwarded to the underlay next hop.

Note: It is possible to compress the frame structure to better
utilize the header, but this would come at the expense of crossing
byte boundaries. For ease of implementation, and so that QoS-stamping
QoS stamping is applied on an extremely small subset of user plane user-plane
traffic, we believe that the above structure is a pragmatic
compromise between header efficiency and ease of implementation.

4.2. KPI-stamping KPI-Stamping Encapsulation (Detection Mode)

The format of the NSH MD type Type 2 KPI-stamping TLV (detection mode) is
shown in Figure 11. 10.

This TLV is used for KPI anomaly detection. Upon detecting a problem
or an anomaly anomaly, it will be possible to enable the use of KPI-stamping
extended encapsulations, which will provide more detailed analysis.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|U| TTL | Length |U|U|U|U|Type=2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type=Det(1) |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| KPI Type | Stamping SI | Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold KPI Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress KPI-stamp KPI stamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 10: Generic NSH KPI Encapsulation (Detection Mode)

The following fields are defined in the KPI TSD metadata: KPIDB MD:

o KPI Type: This field determines the type of KPI-stamp KPI stamp that is
included in this metadata field. MD. If a receiver along the path does not
understand the KPI Type type, it will pass the packet on transparently
and will not drop. drop it. The supported values of the KPI Type are:
0x0

* 0x0: Timestamp
0x1 QoS-stamp

* 0x1: QoS stamp
o Threshold KPI Value: In the first header header, the SFC classifier may
program a KPI threshold value. This is a value that that, when
exceeded, requires the SF to insert the current SI value into the
SI field. The KPI type is the type of KPI stamp inserted into the
header as per section 9. Figure 10.

o Stamping SI: This is the Service Identifier of the SF when the Threshold
above threshold value is exceeded.

o Flow ID: The flow Flow ID is inserted into the header by the SFC
classifier in order to correlate flow data in the KPIDB for
offline analysis.

o Ingress KPI-stamp: KPI stamp: The last 8 octets are reserved for the KPI-
KPI stamp. This is the KPI value at the chain ingress at the SFC
classifier. Depending on the KPI Type, type, the KPI-stamp either KPI stamp includes
either a timestamp or a QoS-stamp. QoS stamp. If the KPI Type type is Timestamp,
then the Ingress KPI-stamp KPI stamp field contains a timestamp in 64-bit
NTP timestamp format. If the KPI
Type type is QoS-stamp, QoS stamp, then the
format of the 64-bit Ingress KPI-stamp KPI stamp is as follows.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QT | QoS Value | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 11: QoS-stamp QoS-Stamp Format (Detection Mode)

As an example operation, let's say we are using KPI type 0x01 (timestamp)
when a service function (SFn)
(Timestamp). When an SF (say SFn) receives the packet packet, it can
compare the current local timestamp (it first checks that it is
synchronized to
network the network's PRC) with the chain ingress timestamp Ingress Timestamp
to calculate the latency in the chain. If this value exceeds the
timestamp threshold, it then inserts its SI and returns the NSH to
the KPIDB. This effectively tells the system that at SFn the packet
violated the KPI threshold. Please refer to figure 9 Figure 8 for the
timestamp format.

When this occurs occurs, the SFC control plane control-plane system would then invoke the
KPI extended mode, which uses a more sophisticated (and intrusive)
method to isolate KPI violation the root cause of the KPI violation, as described
below.

Note: Whilst detection mode is a valuable tool for latency actions,
the authors feel that it is not justified to build building the logic into the KPI system for QoS configuration.
configuration is not justified. As QoS-stamping QoS stamping is done infrequently
and on a tiny percentage of the user plane, it is more practical to
use extended mode only for service chain QoS verification.

5. Hybrid Models

A hybrid chain may be defined as a chain whereby there is a mix of
NSH-aware and NSH-unaware SFs.

Example 1.

Figure 12 shows an example of a hybrid chain with a PNF in the middle

Stamp
middle.

Stamping
Controller
| KPIDB
| SCP Interface |
,---. ,---. ,---. ,---.
/ \ / \ / \ / \
( SCL )-------->( SF1 )--------->( SF2 )--------->( SFn )
\ FSN / \ / \ PNF1/ \ LSN /
`---' `---' `---' `---'

Figure 12: Hybrid chain Chain with PNF in middle Middle

In this example example, the FSN begins its operation and sets the SI to 3, 3.
SF1 decrements this the SI to 2 and passes the packet to an SFC proxy
(not shown).

The SFC proxy strips the NSH and passes the packet to the PNF. On
receipt back from the PNF, the proxy decrements the SI and passes the
packet onto to the LSN with a SI=1.

After the LSN processes the traffic traffic, it knows from the SI value that
it is the last node on
the chain from in the SI value chain, and it exports the entire NSH and
all
metadata MD to the KPIDB. The payload is forwarded to the next hop on the
underlay minus the NSH. The stamping information packet may be given
a new SPI to act as a homing tag to transport the stamp data back to
the KPIDB.

Example 2.

Figure 13 shows an example of a hybrid chain with a PNF at the end

Stamp end.

Stamping
Controller
| KPIDB
| SCP Interface |
,---. ,---. ,---. ,---.
/ \ / \ / \ / \
( SCL )-------->( SF1 )--------->( SF2 )--------->( PNFN )
\ FSN / \ / \ LSN / \ /
`---' `---' `---' `---'

Figure 13: Hybrid Chain with PNF at end End

In this example example, the FSN begins its operation and sets the SI to 3, the 3.
The SSI field is set to 0x1, and the type is set to 1. Thus, when
SF2 receives the packet with SI=1, it understands that it is expected
to take on the role of the LSN LSN, as it is the last NSH-aware node in
the chain.

5.1. Targeted VNF Stamp Stamping

For the majority of flows within the service chain, stamps (ingress,
egress (Ingress
stamps, Egress stamps, or both) will be carried out at each hop until
the SI decrements to zero and the NSH and Stamp stamp MD is are exported to
the KPIDB.
There may exist however However, the need to just test a particular VNF may exist
(perhaps after a scale out scale-out operation, software upgrade upgrade, or underlay
change
change, for example). In this case case, the FSN should mark the NSH as
follows:

o The SSI field is set to 0x2.

o Type is set to the expected SI at the SF in question.

o When the outer SI is equal to the SSI, stamps are applied at the
SF ingress and egress, and the NSH and MD are exported to the
KPIDB.

6. Fragmentation Considerations

The method methods described in this document does do not support fragmentation.
The SC should return an error should a stamping request from an
external system exceed MTU limits and require fragmentation.

Depending on the length of the payload and the type of KPI-stamp KPI stamp and
chain length, this will vary for each packet.

In most service provider architectures architectures, we would expect a SI << 10,
and that
which may include some PNFs in the chain which that do not add overhead. Thus
Thus, for typical IMIX Internet Mix (IMIX) packet sizes [RFC6985], we
expect to be able to perform timestamping on the vast majority of
flows without
fragmenting. Thus fragmentation. Thus, the classifier can have apply a simple
rule to that only allow
KPI-stamping allows KPI stamping on packet sizes less than 1200 bytes
bytes, for example.

7. Security Considerations

The security considerations of for the NSH in general are discussed in
[RFC8300].

The use of in-band

In-band timestamping, as defined in this document, can be used as a
means for network reconnaissance. By passively eavesdropping to on
timestamped traffic, an attacker can gather information about network
delays and performance bottlenecks.

The NSH timestamp is intended to be used by various applications to
monitor the network performance and to detect anomalies. Thus, a man-
in-the-middle
man-in-the-middle attacker can maliciously modify timestamps in order
to attack applications that use the timestamp values. For example,
an attacker could manipulate the SFC classifier operation, such that
it forwards traffic through 'better' behaving "better-behaved" chains. Furthermore, if
timestamping is performed on a fraction of the traffic, an attacker
can selectively induce synthetic delay only to timestamped packets,
causing systematic error in the measurements. packets
and can systematically trigger measurement errors.

Similarly, if an attacker can modify QoS stamps, erroneous values may
be imported into the KPIDB, resulting is in further misconfiguration and
subscriber QoE impairment.

An attacker that gains access to the SCP can enable time timestamping and QoS-
QoS stamping for all subscriber flows, thereby causing performance
bottlenecks, fragmentation, or outages.

As discussed in previous sections, NSH timestamping relies on an
underlying time synchronization protocol. Thus, by attacking the
time
protocol protocol, an attack attacker can potentially compromise the integrity
of the NSH timestamp. A detailed discussion about the threats
against time protocols and how to mitigate them is presented in
[RFC7384].

8. IANA Considerations

This document makes has no requests for IANA action, actions.

9. Contributors

This document originated as draft-browne-sfc-nsh-timestamp-00 and had
the following co-authors and contributors. We would like to thank and
recognize them and their contributions.

Yoram Moses

Technion

moses@ee.technion.ac.il

Brendan Ryan

Intel Corporation

brendan.ryan@intel.com

10. Acknowledgments

This document was prepared using 2-Word-v2.0.template.dot.

The authors gratefully acknowledge Mohamed Boucadair, Martin
Vigoureux and Adrian Farrel for their thorough reviews and helpful
comments.

11. References

11.1.

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. 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC7665] Halpern, J., Ed., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015, <https://www.rfc-
editor.org/info/rfc7665>.
<https://www.rfc-editor.org/info/rfc7665>.

[RFC8174] B. Leiba, B., "Ambiguity of Uppercase vs Lowercase in
RFC 2119 Key Words", RFC8174, BCP 14, RFC 8174,
DOI 10.17487/RFC8174, May 2017. 2017,
<https://www.rfc-editor.org/info/rfc8174>.

[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, C., Ed.,
"Network Service Header (NSH)", RFC 8300, 2018.

11.2.
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.

9.2. Informative References

[IEEE1588] IEEE TC 9 Instrumentation and Measurement Society,
"1588 IEEE
IEEE, "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems Version 2", Systems",
IEEE Standard, 2008.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26, RFC
5226, May 2008. Standard 1588,
<https://standards.ieee.org/standard/1588-2008.html>.

[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, W.,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010. 2010,
<https://www.rfc-editor.org/info/rfc5905>.

[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014.

[TS] Mizrahi, T., Fabini, J., and A. 2014, <https://www.rfc-editor.org/info/rfc7384>.

[RFC6985] Morton, "Guidelines
for Defining A., "IMIX Genome: Specification of Variable Packet Timestamps", draft-ietf-ntp-
packet-timestamps (work in progress), 2018.
Sizes for Additional Testing", RFC 6985,
DOI 10.17487/RFC6985, July 2013,
<https://www.rfc-editor.org/info/rfc6985>.

[Y.1731] ITU-T Recommendation G.8013/Y.1731, "OAM Functions "Operations,
administration and
Mechanisms maintenance (OAM) functions and
mechanisms for Ethernet-based Networks", networks", August 2015.

[Y.1564] ITU-T Recommendation Y.1564, "Ethernet service
activation test methodology", March 2011. 2015,
<https://www.itu.int/rec/T-REC-G.8013/en>.

[G.8261] ITU-T Recommendation G.8261/Y.1361, "Timing and
synchronization aspects in packet networks", August
2013. 2013,
<https://www.itu.int/rec/T-REC-G.8261>.

[G.8262] ITU-T Recommendation G.8262/Y.1362, "Timing
characteristics of a synchronous Ethernet equipment slave
clock", January 2015. November 2018,
<https://www.itu.int/rec/T-REC-G.8262>.

[G.8264] ITU-T Recommendation G.8264/Y.1364, "Distribution of
timing information through packet networks", May 2014.

[I-D.ippm.ioam] August 2017,
<https://www.itu.int/rec/T-REC-G.8264>.

[In-Situ-OAM]
Brockners, Bhandari et al. F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., Chang, R., Bernier, D., and J. Lemon, "Data Fields for
In-situ OAM"
draft-ietf-ippm-ioam-data-03 (work OAM", Work in progress), June
2018 Progress,
draft-ietf-ippm-ioam-data-05, March 2019.

Acknowledgments

The authors gratefully acknowledge Mohamed Boucadair, Martin
Vigoureux, and Adrian Farrel for their thorough reviews and helpful
comments.

Contributors

This document originated as draft-browne-sfc-nsh-timestamp-00; the
following people were coauthors of that draft. We would like to
thank them and recognize them for their contributions.

Yoram Moses
Technion
Email: moses@ee.technion.ac.il

Brendan Ryan
Intel Corporation
Email: brendan.ryan@intel.com

Authors' Addresses

Rory Browne
Intel
Dromore House
Shannon
Co.Clare
Co. Clare
Ireland

Email: rory.browne@intel.com rorybrowne@yahoo.com

Andrey Chilikin
Intel
Dromore House
Shannon
Co.Clare
Co. Clare
Ireland

Email: andrey.chilikin@intel.com

Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel

Email: tal.mizrahi.phd@gmail.com