Hi Dale,
thank you for your kind consideration of the proposed updates, thoughtful and helpful suggestions. I've clipped parts of our discussion that we've agreed on the changes. My follow-up notes are in-lined under GIM2>> tag.
Attached, please find the updated working version and its diff to -07 version of the STAMP draft.
Regards,
Greg
On Sun, Oct 13, 2019 at 6:03 PM Dale R. Worley <worley@xxxxxxxxxxx> wrote:
> From: Greg Mirsky <gregimirsky@xxxxxxxxx>
>
> Hi Dale,
> hope this friendly reminder finds you well. I much appreciate your
> consideration of the responses to your helpful comments.
My apologies for the delay.
All of this looks good. Although there are a couple of minor points
that I've added below.
On Mon, Sep 30, 2019 at 5:17 PM Greg Mirsky <gregimirsky@xxxxxxxxx> wrote:
> Hi Dale,
> thank you for your review, comments, and suggestions. Please find answers
> and notes in-line under the GIM>> tag.
> Attached, please find the diff between -07 and the current working
> version, as well as, the working version of the draft.
>
> Regards,
> Greg
>
> On Tue, Sep 3, 2019 at 6:01 PM Dale Worley via Datatracker <
> noreply@xxxxxxxx> wrote:
>
>> ----------------------------------------------------------------------
>> I am the assigned Gen-ART reviewer for this draft. The General Area
>> Review Team (Gen-ART) reviews all IETF documents being processed
>> by the IESG for the IETF Chair. Please treat these comments just
>> like any other last call comments.
>>
>> For more information, please see the FAQ at
>>
>> <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.
>>
>> Document: draft-ietf-ippm-stamp-07
>> Reviewer: Dale R. Worley
>> Review Date: 2019-09-03
>> IETF LC End Date: 2019-09-03
>> IESG Telechat date: 2019-09-19
>>
>> Summary:
>>
>> This draft is on the right track but has open issues, described
>> in the review.
>>
>> Editorial issues:
>>
>> 1. Introduction
>>
>> and inherit separation of control (vendor-specific configuration or
>> orchestration) and test functions.
>>
>> Is "inherit" intended to be "inherent"?
>>
> GIM>> Thank you. That was the intention. Done.
>>
>> One of such is Performance
>> Measurement from IP Edge to Customer Equipment using TWAMP Light from
>> Broadband Forum [BBF.TR-390] used as the reference TWAMP Light that,
>> according to [RFC8545], includes sub-set of TWAMP-Test functions in
>> combination with other applications that provide, for example,
>> control and security.
>>
>> This sentence is awkward because of the length of the title in the
>> middle of the sentence. Perhaps
>>
>> One of such is [BBF.TR-390] (Performance Measurement from IP Edge
>> to Customer Equipment using TWAMP Light from the Broadband Forum),
>> a the reference TWAMP Light, that includes a sub-set of TWAMP-Test
>> functions along with control and security functions.
>>
> GIM>> Thank you for the proposed text. While addressing other comments the
> text has been transformed to the following:
> CURRENT TEXT:
> Recent work on IP Edge to Customer Equipment using TWAMP Light from
> Broadband Forum [BBF.TR-390] demonstrated that interoperability among
> implementations of TWAMP Light is challenged because the composition
> and operation of TWAMP Light were not sufficiently specified in
> [RFC5357]. According to [RFC8545], TWAMP Light includes sub-set of
> TWAMP-Test functions to provide comprehensive solution requires
> support by other applications that provide, for example, control and
> security.
> Hope the current version is clearer and more readable.
I would change "interoperability among implementations of TWAMP Light
is challenged" to "interoperability among TWAMP Light implementations
is poor", or perhaps "... is difficult".
GIM2>> Will use "difficult".
In the last sentence, I think there are words missing from "to provide
comprehensive solution requires support"; perhaps "to provide a
comprhenesive soultion with support"?
GIM2>> I agree, that sentence is awkward. Here's its update:
OLD TEXT:
According to [RFC8545], TWAMP Light includes sub-set ofTWAMP-Test functions to provide comprehensive solution requires
support by other applications that provide, for example, control and
security.
NEW TEXT:
According to [RFC8545], TWAMP Light includes a sub-set of
TWAMP-Test functions. Thus, to have a comprehensive tool to measure
packet loss and delay requires support by other applications that
provide, for example, control and security.
TWAMP-Test functions. Thus, to have a comprehensive tool to measure
packet loss and delay requires support by other applications that
provide, for example, control and security.
>> o Timestamp is eight octets long field. STAMP node MUST support
>> Network Time Protocol (NTP) version 4 64-bit timestamp format
>> [RFC5905], the format used in [RFC5357]. STAMP node MAY support
>> IEEE 1588v2 Precision Time Protocol truncated 64-bit timestamp
>> format [IEEE.1588.2008], the format used in [RFC8186].
>>
>> The specification of how the time format for a particular packet is
>> chosen is weak. I think you want to add to the above paragraph that
>> the choice of format is determined either by configuration or the Z
>> bit in the Error Estimate field.
>>
> GIM>> In regard to the format of a timestamp, STAMP specification follows
> the idea of RFC 8186 where extension to negotiate timestamp format for
> TWAMP-Control and the new interpretation of Z flag were defined. For STAMP,
> as defined for TWAMP, the value of the Z flag in the Error Estimate field
> is only to reflect the format used by the node.
In that case, I think you want to add to the definition of the
timestamp field that the format it uses is part of the configuration
of the session. In any situation, it must be clear how the receiver
of a STAMP packet determines how to interpret the Timestamp value.
GIM2>> Thank you for the suggestion. I've added the sentence to the definition of Timestamp:
o Timestamp is eight octets long field. STAMP node MUST support
Network Time Protocol (NTP) version 4 64-bit timestamp format[RFC5905], the format used in [RFC5357]. STAMP node MAY support
IEEE 1588v2 Precision Time Protocol (PTP) truncated 64-bit
timestamp format [IEEE.1588.2008], the format used in [RFC8186].
The use of the specific format, NTP or PTP, is part of
configuration of the Session-Sender or the particular test
session.
>> 4.1.2. Session-Sender Packet Format in Authenticated Mode
>>
>> Also, MBZ fields are used to align the packet on 16 octets
>> boundary.
>>
>> You can't align the packet itself using a field within the packet.
>> You want to say "are used to align the fields within the packet on 16
>> octets boundaries." Or perhaps "to make the packet length a multiple
>> of 16 octets." Similarly in 4.2.1 and 4.2.2.
>>
> GIM>> Thank you for the suggested text. I've used the second option.
>
>>
>> 4.2. Session-Reflector Behavior and Packet Format
>>
>> Two modes of STAMP Session-Reflector characterize the expected
>> behavior and, consequently, performance metrics that can be measured:
>>
>> o Stateless - STAMP Session-Reflector does not maintain test state
>> and will reflect the received sequence number without
>> modification. As a result, only round-trip packet loss can be
>> calculated while the reflector is operating in stateless mode.
>>
>> o Stateful - STAMP Session-Reflector maintains test state thus
>> enabling the ability to determine forward loss, gaps recognized in
>> the received sequence number. As a result, both near-end
>> (forward) and far-end (backward) packet loss can be computed.
>> That implies that the STAMP Session-Reflector MUST keep a state
>> for each accepted STAMP-test session, uniquely identifying STAMP-
>> test packets to one such session instance, and enabling adding a
>> sequence number in the test reply that is individually incremented
>> on a per-session basis.
>>
>> This seems important enough -- the mode determines what data STAMP
>> can measure -- to be promoted to part of section 4, "Theory of
>> Operation".
>>
> GIM>> I agree. Moved the text to Section 4 and re-named this section to
> Session-Reflector Packet Format
That looks good, except that the first words of para 4 are
"STAMP supports two modes:", just after para 2 and 3 define two
*other* modes. So I'd change para 4 to start "STAMP supports two
authentication modes:".
GIM2>> Agree. Thank you.
Dale
Network Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track G. Jun
Expires: April 16, 2020 ZTE Corporation
H. Nydell
Accedian Networks
R. Foote
Nokia
October 14, 2019
Simple Two-way Active Measurement Protocol
draft-ietf-ippm-stamp-09
Abstract
This document describes a Simple Two-way Active Measurement Protocol
which enables the measurement of both one-way and round-trip
performance metrics like delay, delay variation, and packet loss.
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
working documents as Internet-Drafts. The list of current Internet-
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 April 16, 2020.
Copyright Notice
Copyright (c) 2019 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Operation and Management of Performance Measurement Based on
STAMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4
4.1. UDP Port Numbers in STAMP Testing . . . . . . . . . . . . 5
4.2. Session-Sender Behavior and Packet Format . . . . . . . . 5
4.2.1. Session-Sender Packet Format in Unauthenticated Mode 5
4.2.2. Session-Sender Packet Format in Authenticated Mode . 7
4.3. Session-Reflector Behavior and Packet Format . . . . . . 8
4.3.1. Session-Reflector Packet Format in Unauthenticated
Mode . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3.2. Session-Reflector Packet Format in Authenticated Mode 9
4.4. Integrity Protection in STAMP . . . . . . . . . . . . . . 11
4.5. Confidentiality Protection in STAMP . . . . . . . . . . . 11
4.6. Interoperability with TWAMP Light . . . . . . . . . . . . 11
5. Operational Considerations . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Development and deployment of the Two-Way Active Measurement Protocol
(TWAMP) [RFC5357] and its extensions, e.g., [RFC6038] that defined
Symmetrical Size for TWAMP, provided invaluable experience. Several
independent implementations of both TWAMP and TWAMP Light exist, have
been deployed, and provide important operational performance
measurements.
At the same time, there has been noticeable interest in using a more
straightforward mechanism for active performance monitoring that can
provide deterministic behavior and inherent separation of control
(vendor-specific configuration or orchestration) and test functions.
Recent work on IP Edge to Customer Equipment using TWAMP Light from
Broadband Forum [BBF.TR-390] demonstrated that interoperability among
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implementations of TWAMP Light is difficult because the composition
and operation of TWAMP Light were not sufficiently specified in
[RFC5357]. According to [RFC8545], TWAMP Light includes a sub-set of
TWAMP-Test functions. Thus, to have a comprehensive tool to measure
packet loss and delay requires support by other applications that
provide, for example, control and security.
This document defines an active performance measurement test
protocol, Simple Two-way Active Measurement Protocol (STAMP), that
enables measurement of both one-way and round-trip performance
metrics like delay, delay variation, and packet loss. Some TWAMP
extensions, e.g., [RFC7750] are supported by the extensions to STAMP
base specification in [I-D.ietf-ippm-stamp-option-tlv].
2. Conventions used in this document
2.1. Terminology
STAMP - Simple Two-way Active Measurement Protocol
NTP - Network Time Protocol
PTP - Precision Time Protocol
HMAC Hashed Message Authentication Code
OWAMP One-Way Active Measurement Protocol
TWAMP Two-Way Active Measurement Protocol
MBZ Must be Zero
2.2. 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.
3. Operation and Management of Performance Measurement Based on STAMP
Figure 1 presents the Simple Two-way Active Measurement Protocol
(STAMP) Session-Sender, and Session-Reflector with a measurement
session. In this document, a measurement session also referred to as
STAMP session, is the bi-directional packet flow between one specific
Session-Sender and one particular Session-Reflector for a time
duration. The configuration and management of the STAMP Session-
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Sender, Session-Reflector, and management of the STAMP sessions are
outside the scope of this document and can be achieved through
various means. A few examples are: Command Line Interface,
telecommunication services' OSS/BSS systems, SNMP, and Netconf/YANG-
based SDN controllers.
o----------------------------------------------------------o
| Configuration and |
| Management |
o----------------------------------------------------------o
|| ||
|| ||
|| ||
+----------------------+ +-------------------------+
| STAMP Session-Sender | <--- STAMP---> | STAMP Session-Reflector |
+----------------------+ +-------------------------+
Figure 1: STAMP Reference Model
4. Theory of Operation
STAMP Session-Sender transmits test packets over UDP transport toward
STAMP Session-Reflector. STAMP Session-Reflector receives Session-
Sender's packet and acts according to the configuration. Two modes
of STAMP Session-Reflector characterize the expected behavior and,
consequently, performance metrics that can be measured:
o Stateless - STAMP Session-Reflector does not maintain test state
and will use the value in the Sequence Number field in the
received packet as the value for the Sequence Number field in the
reflected packet. As a result, values in Sequence Number and
Session-Sender Sequence Number fields are the same, and only
round-trip packet loss can be calculated while the reflector is
operating in stateless mode.
o Stateful - STAMP Session-Reflector maintains test state thus
enabling the ability to determine forward loss, gaps recognized in
the received sequence number. As a result, both near-end
(forward) and far-end (backward) packet loss can be computed.
That implies that the STAMP Session-Reflector MUST keep a state
for each configured STAMP-test session, uniquely identifying
STAMP-test packets to one such session instance, and enabling
adding a sequence number in the test reply that is individually
incremented on a per-session basis.
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STAMP supports two authentication modes: unauthenticated and
authenticated. Unauthenticated STAMP test packets, defined in
Section 4.2.1 and Section 4.3.1, ensure interworking between STAMP
and TWAMP Light as described in Section 4.6 packet formats.
By default, STAMP uses symmetrical packets, i.e., size of the packet
transmitted by Session-Reflector equals the size of the packet
received by the Session-Reflector.
4.1. UDP Port Numbers in STAMP Testing
A STAMP Session-Sender MUST use UDP port 862 (TWAMP-Test Receiver
Port) as the default destination UDP port number. A STAMP
implementation of Session-Sender MUST be able to use as the
destination UDP port numbers from User, a.k.a. Registered, Ports and
Dynamic, a.k.a. Private or Ephemeral, Ports ranges defined in
[RFC6335]. Before using numbers from the User Ports range, the
possible impact on the network MUST be carefully studied and agreed
by all users of the network domain where the test has been planned.
An implementation of STAMP Session-Reflector by default MUST receive
STAMP test packets on UDP port 862. An implementation of Session-
Reflector that supports this specification MUST be able to define the
port number to receive STAMP test packets from User Ports and Dynamic
Ports ranges that are defined in [RFC6335]. STAMP defines two
different test packet formats, one for packets transmitted by the
STAMP-Session-Sender and one for packets transmitted by the STAMP-
Session-Reflector.
4.2. Session-Sender Behavior and Packet Format
A STAMP Session-Reflector supports symmetrical size of test packets
[RFC6038] as the default behavior. Because of that, the base STAMP
Session-Sender packet has a minimum size of 44 octets in
unauthenticated mode, see Figure 2, and 112 octets in the
authenticated mode, see Figure 4. The variable length of a test
packet in STAMP is supported by using Extra Padding TLV defined in
[I-D.ietf-ippm-stamp-option-tlv].
4.2.1. Session-Sender Packet Format in Unauthenticated Mode
STAMP Session-Sender packet format in unauthenticated mode:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
| |
| Reserved (30 octets) |
| |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: STAMP Session-Sender test packet format in unauthenticated
mode
where fields are defined as the following:
o Sequence Number is four octets long field. For each new session
its value starts at zero and is incremented with each transmitted
packet.
o Timestamp is eight octets long field. STAMP node MUST support
Network Time Protocol (NTP) version 4 64-bit timestamp format
[RFC5905], the format used in [RFC5357]. STAMP node MAY support
IEEE 1588v2 Precision Time Protocol (PTP) truncated 64-bit
timestamp format [IEEE.1588.2008], the format used in [RFC8186].
The use of the specific format, NTP or PTP, is part of
configuration of the Session-Sender or the particular test
session.
o Error Estimate is two octets long field with format displayed in
Figure 3
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|Z| Scale | Multiplier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Error Estimate Format
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where S, Scale, and Multiplier fields are interpreted as they have
been defined in section 4.1.2 [RFC4656]; and Z flag - as has been
defined in section 2.3 [RFC8186]:
* 0 - NTP 64 bit format of a timestamp;
* 1 - PTPv2 truncated format of a timestamp.
The STAMP Session-Sender and Session-Reflector MUST use the NTP 64
bit format of a timestamp (Z field value of 0). as the default.
A configuration/management function MAY configure STAMP Session-
Sender and Session-Reflector to using the PTPv2 truncated format
of a timestamp (Z field value of 1).
o Reserved field in the Session-Sender unauthenticated packet is 30
octets long. It MUST be all zeroed on the transmission and MUST
be ignored on receipt.
4.2.2. Session-Sender Packet Format in Authenticated Mode
STAMP Session-Sender packet format in authenticated mode:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| MBZ (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
~ ~
| MBZ (70 octets) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: STAMP Session-Sender test packet format in authenticated
mode
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The field definitions are the same as the unauthenticated mode,
listed in Section 4.2.1. Also, Must-Be-Zero (MBZ) fields are used to
to make the packet length a multiple of 16 octets. The value of the
field MUST be zeroed on transmission and MUST be ignored on receipt.
Also, the packet includes a key-hashed message authentication code
(HMAC) ([RFC2104]) hash at the end of the PDU. The detailed use of
the HMAC field is described in Section 4.4.
4.3. Session-Reflector Behavior and Packet Format
The Session-Reflector receives the STAMP test packet, verifies it,
prepares and transmits the reflected test packet.
4.3.1. Session-Reflector Packet Format in Unauthenticated Mode
For unauthenticated mode:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Error Estimate | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ses-Sender TTL | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: STAMP Session-Reflector test packet format in
unauthenticated mode
where fields are defined as the following:
o Sequence Number is four octets long field. The value of the
Sequence Number field is set according to the mode of the STAMP
Session-Reflector:
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* in the stateless mode, the Session-Reflector copies the value
from the received STAMP test packet's Sequence Number field;
* in the stateful mode, the Session-Reflector counts the
transmitted STAMP test packets. It starts with zero and is
incremented by one for each subsequent packet for each test
session. The Session-Reflector uses that counter to set the
value of the Sequence Number field.
o Timestamp and Receive Timestamp fields are each eight octets long.
The format of these fields, NTP or PTPv2, indicated by the Z flag
of the Error Estimate field as described in Section 4.2. Receive
Timestamp is the time the test packet was received by the Session-
Reflector. Timestamp - the time taken by the Session-Reflector at
the start of transmitting the test packet.
o Error Estimate has the same size and interpretation as described
in Section 4.2. It is applicable to both Timestamp and Receive
Timestamp.
o Session-Sender Sequence Number, Session-Sender Timestamp, and
Session-Sender Error Estimate are copies of the corresponding
fields in the STAMP test packet sent by the Session-Sender.
o Session-Sender TTL is one octet long field, and its value is the
copy of the TTL field in IPv4 (or Hop Limit in IPv6) from the
received STAMP test packet.
o MBZ is used to achieve alignment of fields within the packet on a
four octets boundary. The value of the field MUST be zeroed on
transmission and MUST be ignored on receipt.
o Reserved field in the Session-Reflector unauthenticated packet is
three octets long. It MUST be all zeroed on the transmission and
MUST be ignored on receipt.
4.3.2. Session-Reflector Packet Format in Authenticated Mode
For the authenticated mode:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MBZ (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session-Sender Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MBZ (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ses-Sender TTL | |
+-+-+-+-+-+-+-+-+ +
| |
| MBZ (15 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: STAMP Session-Reflector test packet format in authenticated
mode
The field definitions are the same as the unauthenticated mode,
listed in Section 4.3.1. Additionally, the MBZ field is used to to
make the packet length a multiple of 16 octets. The value of the
field MAY be zeroed on transmission and MUST be ignored on receipt.
Also, STAMP Session-Reflector test packet format in authenticated
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mode includes a keyed (HMAC) ([RFC2104]) hash at the end of the PDU.
The detailed use of the HMAC field is in Section 4.4.
4.4. Integrity Protection in STAMP
Authenticated mode provides integrity protection to each STAMP
message by adding Hashed Message Authentication Code (HMAC). STAMP
uses HMAC-SHA-256 truncated to 128 bits (similarly to the use of it
in IPSec defined in [RFC4868]); hence the length of the HMAC field is
16 octets. In the Authenticated mode, HMAC covers the first six
blocks (96 octets). HMAC uses its own key; key management and the
mechanisms to distribute the HMAC key is outside the scope of this
specification. One example is to use an orchestrator to configure
HMAC key based on STAMP YANG data model [I-D.ietf-ippm-stamp-yang].
HMAC MUST be verified as early as possible to avoid using or
propagating corrupted data.
4.5. Confidentiality Protection in STAMP
If confidentiality protection for STAMP is required, a STAMP test
session MUST use a secured transport. For example, STAMP packets
could be transmitted in the dedicated IPsec tunnel or share the IPsec
tunnel with the monitored flow. Also, Datagram Transport Layer
Security protocol would provide the desired confidentiality
protection.
4.6. Interoperability with TWAMP Light
One of the essential requirements to STAMP is the ability to
interwork with a TWAMP Light device. Because STAMP and TWAMP use
different algorithms in Authenticated mode (HMAC-SHA-256 vs. HMAC-
SHA-1), interoperability is only considered for Unauthenticated mode.
There are two possible combinations for such use case:
o STAMP Session-Sender with TWAMP Light Session-Reflector;
o TWAMP Light Session-Sender with STAMP Session-Reflector.
In the former case, the Session-Sender might not be aware that its
Session-Reflector does not support STAMP. For example, a TWAMP Light
Session-Reflector may not support the use of UDP port 862 as
specified in [RFC8545]. Thus Section 4. permits a STAMP Session-
Sender to use alternative ports. If any of STAMP extensions are
used, the TWAMP Light Session-Reflector will view them as Packet
Padding field.
In the latter scenario, if a TWAMP Light Session-Sender does not
support the use of UDP port 862, the test management system MUST set
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STAMP Session-Reflector to use UDP port number, as permitted by
Section 4. The Session-Reflector MUST be set to use the default
format for its timestamps, NTP.
A STAMP Session-Reflector that supports this specification would
transmit the base packet (Figure 5) regardless of the size of the
Padding field in the packet received from TWAMP Session-Sender.
Also, STAMP does not support the Reflect Octets capability defined in
[RFC6038]. If the Server Octets field is present in the TWAMP
Session-Sender packet, STAMP Session-Reflector will not copy the
content starting from the Server Octets field and will transmit the
reflected packet, as displayed in Figure 5.
5. Operational Considerations
STAMP is intended to be used on production networks to enable the
operator to assess service level agreements based on packet delay,
delay variation, and loss. When using STAMP over the Internet,
especially when STAMP test packets are transmitted with the
destination UDP port number from the User Ports range, the possible
impact of the STAMP test packets MUST be thoroughly analyzed. The
use of STAMP for each case MUST be agreed by users of nodes hosting
the Session-Sender and Session-Reflector before starting the STAMP
test session.
Also, the use of the well-known port number as the destination UDP
port number in STAMP test packets transmitted by a Session-Sender
would not impede the ability to measure performance in an Equal Cost
Multipath environment and analysis in Section 5.3 [RFC8545] fully
applies to STAMP.
6. IANA Considerations
This document doesn't have any IANA action. This section may be
removed before the publication.
7. Security Considerations
[RFC5357] does not identify security considerations specific to
TWAMP-Test but refers to security considerations identified for OWAMP
in [RFC4656]. Since both OWAMP and TWAMP include control plane and
data plane components, only security considerations related to OWAMP-
Test, discussed in Sections 6.2, 6.3 [RFC4656] apply to STAMP.
STAMP uses the well-known UDP port number allocated for the OWAMP-
Test/TWAMP-Test Receiver port. Thus the security considerations and
measures to mitigate the risk of the attack using the registered port
number documented in Section 6 [RFC8545] equally apply to STAMP.
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Because of the control and management of a STAMP test being outside
the scope of this specification only the more general requirement is
set:
To mitigate the possible attack vector, the control, and
management of a STAMP test session MUST use the secured transport.
The load of the STAMP test packets offered to a network MUST be
carefully estimated, and the possible impact on the existing
services MUST be thoroughly analyzed before launching the test
session. [RFC8085] section 3.1.5 provides guidance on handling
network load for UDP-based protocol. While the characteristic of
test traffic depends on the test objective, it is highly
recommended to stay in the limits as provided in [RFC8085].
Use of HMAC-SHA-256 in the authenticated mode protects the data
integrity of the STAMP test packets.
8. Acknowledgments
Authors express their appreciation to Jose Ignacio Alvarez-Hamelin
and Brian Weis for their great insights into the security and
identity protection, and the most helpful and practical suggestions.
Also, our sincere thanks to David Ball and Rakesh Gandhi or their
thorough reviews and helpful comments.
9. References
9.1. Normative References
[I-D.ietf-ippm-stamp-option-tlv]
Mirsky, G., Xiao, M., Jun, G., Nydell, H., Foote, R., and
A. Masputra, "Simple Two-way Active Measurement Protocol
Optional Extensions", draft-ietf-ippm-stamp-option-tlv-01
(work in progress), September 2019.
[IEEE.1588.2008]
"Standard for a Precision Clock Synchronization Protocol
for Networked Measurement and Control Systems",
IEEE Standard 1588, March 2008.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>.
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[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>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<https://www.rfc-editor.org/info/rfc4656>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<https://www.rfc-editor.org/info/rfc5357>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, DOI 10.17487/RFC6038, October 2010,
<https://www.rfc-editor.org/info/rfc6038>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
[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>.
[RFC8186] Mirsky, G. and I. Meilik, "Support of the IEEE 1588
Timestamp Format in a Two-Way Active Measurement Protocol
(TWAMP)", RFC 8186, DOI 10.17487/RFC8186, June 2017,
<https://www.rfc-editor.org/info/rfc8186>.
[RFC8545] Morton, A., Ed. and G. Mirsky, Ed., "Well-Known Port
Assignments for the One-Way Active Measurement Protocol
(OWAMP) and the Two-Way Active Measurement Protocol
(TWAMP)", RFC 8545, DOI 10.17487/RFC8545, March 2019,
<https://www.rfc-editor.org/info/rfc8545>.
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9.2. Informative References
[BBF.TR-390]
"Performance Measurement from IP Edge to Customer
Equipment using TWAMP Light", BBF TR-390, May 2017.
[I-D.ietf-ippm-stamp-yang]
Mirsky, G., Xiao, M., and W. Luo, "Simple Two-way Active
Measurement Protocol (STAMP) Data Model", draft-ietf-ippm-
stamp-yang-04 (work in progress), September 2019.
[RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
384, and HMAC-SHA-512 with IPsec", RFC 4868,
DOI 10.17487/RFC4868, May 2007,
<https://www.rfc-editor.org/info/rfc4868>.
[RFC7750] Hedin, J., Mirsky, G., and S. Baillargeon, "Differentiated
Service Code Point and Explicit Congestion Notification
Monitoring in the Two-Way Active Measurement Protocol
(TWAMP)", RFC 7750, DOI 10.17487/RFC7750, February 2016,
<https://www.rfc-editor.org/info/rfc7750>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>.
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@xxxxxxxxx
Guo Jun
ZTE Corporation
68# Zijinghua Road
Nanjing, Jiangsu 210012
P.R.China
Phone: +86 18105183663
Email: guo.jun2@xxxxxxxxxx
Henrik Nydell
Accedian Networks
Email: hnydell@xxxxxxxxxxxx
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Richard Foote
Nokia
Email: footer.foote@xxxxxxxxx
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