Internet DRAFT - draft-mcb-6man-icmpv6-loopback
draft-mcb-6man-icmpv6-loopback
Network T. Mizrahi
Internet-Draft T. Zhou
Intended status: Standards Track S. Belkar
Expires: 9 June 2024 R. Cohen
Huawei
J. Iurman
ULiege
7 December 2023
Internet Control Message Protocol (ICMPv6) Loopback
draft-mcb-6man-icmpv6-loopback-00
Abstract
This document defines ICMPv6 Loopback, which enables a two-way packet
exchange that can be used for probing and for diagnostic purposes.
ICMPv6 Loopback is similar to ICMPv6 Echo, except that after a
Loopback Request is sent, its corresponding Reply includes as much of
the IPv6 Loopback Request packet as possible, including the IPv6
header and IPv6 extension headers and options if they are present.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 9 June 2024.
Copyright Notice
Copyright (c) 2023 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
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirement Language . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
3. ICMPv6 Loopback Messages . . . . . . . . . . . . . . . . . . 5
3.1. Loopback Request Message . . . . . . . . . . . . . . . . 5
3.2. Loopback Reply Message . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. New ICMPv6 Type vs. New Code . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
ICMPv6 Echo [RFC4443] is very commonly used for diagnostic purposes
("Ping"), and is based on a two-way exchange: Node A sends an Echo
Request to Node B, and Node B responds with an Echo Reply to Node A.
The data (payload) of the Echo Reply message is identical to the data
of the invoking Echo Request message.
This document defines ICMPv6 Loopback, using two ICMPv6 message
types: Loopback Request and Loopback Reply. The Loopback procedure
uses a two-way exchange that is similar to the Echo exchange, with
the exception that the payload of the Loopback Reply includes as much
of the invoking IPv6 Loopback Request as possible without exceeding
the MTU, including IPv6 extension headers if they are present.
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+----------------------------+
| IPv6 Header |
|+ optional extension headers|
+----------------------------+
| ICMPv6 Header |
| Loopback Request |
+----------------------------+
| ICMPv6 Data |
+----------------------------+
^ ^
| |
+-----+ +----- Loopback Request -----+ +-----+
| |-------------------------------------------------->| |
| A | | B |
| |<--------------------------------------------------| |
+-----+ +----- Loopback Reply -----+ +-----+
| |
v v
+----------------------------+
| IPv6 Header |
|+ optional extension headers|
+----------------------------+
| ICMPv6 Header |
| Loopback Reply |
+- +----------------------------+
| | IPv6 Header |
| |+ optional extension headers|
Invoking | +----------------------------+
Loopback -+ | ICMPv6 Header |
Request | | Loopback Request |
| +----------------------------+
| | ICMPv6 Data |
+- +----------------------------+
Figure 1: The ICMPv6 Loopback Procedure
It should be noted that ICMPv6 error messages [RFC4443] already
include as much of the IPv6 offending packet as possible. For
example, a node that runs Traceroute receives the inoking packets
back in the returned Time Exceeded messages. The Loopback messages
that are defined in this document enable this information to be
returned to the sender without invoking ICMP error messages.
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ICMPv6 Loopback provides detailed information about the invoking IPv6
packet that is not available in ICMPv6 Echo, including the IPv6
header and extension headers.
A related capability was proposed in the context of the Simple Two-
way Active Measurement Protocol (STAMP): the STAMP extension that was
proposed in [I-D.wang-ippm-stamp-hbh-extensions] allows a STAMP
session-reflector to reflect IPv6 options that were received in test
packets from the session-sender. This functionality is performed
over STAMP, while the ICMPv6 Loopback functionality is performed in
Layer 3, and does not require any parsing or processing beyond Layer
3, namely IPv6 and ICMPv6.
There is a number of in-progress drafts in the IETF that define IPv6
extension headers that can be used for tracing the path and its
performance, including for example,
[I-D.ietf-ippm-ioam-ipv6-options],
[I-D.filsfils-spring-path-tracing], [I-D.ali-spring-ioam-srv6],
[I-D.kumar-ippm-ifa]. These extensions are used for collecting
information along the path of a packet. The collected information is
then exported to a central collector or controller for further
processing. However, there is currently no straightforward way of
sending such trace information back to the sender, while clearly in
some cases this trace information is most relevant to the sender.
ICMPv6 Loopback enables collected trace information along with other
extension headers to be echoed back to the sender in a strightforward
and generic way.
2. Conventions
2.1. Requirement 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.
2.2. Terminology
Abbreviations used in this document:
ICMP: Internet Control Message Protocol
MTU: Maximum Transmission Unit
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3. ICMPv6 Loopback Messages
This document defines two new ICMPv6 types: Loopback Request and
Loopback Reply.
3.1. Loopback Request Message
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-
Figure 2: Loopback Request
IPv6 Fields:
Destination Address Any legal IPv6 address.
ICMPv6 Fields:
Type TBD-LB-Req
Code 0
Identifier An identifier to aid in matching Loopback Replies
to this Loopback Request. May be zero.
Sequence Number A sequence number to aid in matching Loopback
Replies to this Loopback Request. May be zero.
Data Zero or more octets of arbitrary data.
Description
A node that implements the ICMPv6 Echo Request and Reply MAY
implement an ICMPv6 Loopback responder function that receives
Loopback Requests and originates corresponding Loopback Replies. A
node MAY also implement an application-layer interface for
originating Loopback Requests and receiving Loopback Replies, for
diagnostic purposes.
Upper Layer Notification
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Loopback Request messages MAY be passed to processes receiving ICMPv6
messages.
3.2. Loopback Reply Message
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As much of the invoking IPv6 Loopback Request packet |
+ as possible without the ICMPv6 packet +
| exceeding the minimum IPv6 MTU [RFC8200] |
Figure 3: Loopback Reply
IPv6 Fields:
Destination Address Copied from the Source Address field of the
invoking Loopback Request packet.
ICMPv6 Fields:
Type TBD-LB-Rep
Code 0
Identifier The identifier from the invoking Loopback Request
message.
Sequence Number The sequence number from the invoking Loopback
Request message.
Description
A node that implements the ICMPv6 Echo Request and Reply MAY
implement an ICMPv6 Loopback responder function that receives
Loopback Requests and originates corresponding Loopback Replies. A
node MAY also implement an application-layer interface for
originating Loopback Requests and receiving Loopback Replies, for
diagnostic purposes.
The source address of a Loopback Reply sent in response to a unicast
Loopback Request message MUST be the same as the destination address
of that Loopback Request message.
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A Loopback Reply SHOULD be sent in response to a Loopback Request
message sent to an IPv6 multicast or anycast address. In this case,
the source address of the reply MUST be a unicast address belonging
to the interface on which the Loopback Request message was received.
The payload of the ICMPv6 Loopback Reply message, which resides after
the Sequence Number field, MUST include as much of the invoking IPv6
Loopback Request packet without exceeding the IPv6 MTU. Note that if
the invoking packet includes IPv6 extension headers, they are
included in the payload of the Loopback Reply message.
Upper Layer Notification
Loopback Reply messages MUST be passed to the process that originated
a Loopback Request message. A Loopback Reply message MAY be passed
to processes that did not originate the Loopback Request message.
4. IANA Considerations
IANA is requested to allocate the following values in the "Internet
Control Message Protocol version 6 (ICMPv6) Parameters" registry.
Two values are to be allocated from the "ICMPv6 type Numbers" range:
+-------------+---------------------+---------------------------+
| Type | Name | Reference |
+-------------+---------------------+---------------------------+
| TBD-LB-Req | Loopback Request | [This document] |
+-------------+---------------------+---------------------------+
| TBD-LB-Rep | Loopback Reply | [This document] |
+-------------+---------------------+---------------------------+
Figure 4: ICMPv6 Loopback Type Numbers
The two type values should be allocated from one of the unassigned
values greater than 127.
IANA is requested to define a code registry for each of the two new
types. The registration procedure for these registries are First
Come First Served. In each of these new registries, a single code
value is assigned by this document: Code 0.
5. Security Considerations
From a security perspective this document does not introduce new
security threats beyond the threats that are already applicable for
existing ICMPv6 messages, and are described in [RFC4443].
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A ICMPv6 Loopback Reply message may be longer than the invoking
Loopback Request message, since the Loopback Reply includes the
invoking IPv6 packet, encapsulated in an ICMPv6 over IPv6 packet.
Thus, replies are slightly amplified compared to requests. However,
the amplification effect is minor, as it only adds a constant number
of octets to each invoking packet. Notably, the amplification effect
in this case is similar to ICMPv6 error message, and specifically
similar to Traceroute.
6. References
6.1. 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>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
6.2. Informative References
[I-D.ali-spring-ioam-srv6]
Ali, Z., Gandhi, R., Filsfils, C., Brockners, F., Nainar,
N. K., Pignataro, C., Li, C., Chen, M., and G. Dawra,
"Segment Routing Header encapsulation for In-situ OAM
Data", Work in Progress, Internet-Draft, draft-ali-spring-
ioam-srv6-06, 10 July 2022,
<https://datatracker.ietf.org/doc/html/draft-ali-spring-
ioam-srv6-06>.
[I-D.filsfils-spring-path-tracing]
Filsfils, C., Abdelsalam, A., Camarillo, P., Yufit, M.,
Graf, T., Su, Y., Matsushima, S., Valentine, M., and
Dhamija, "Path Tracing in SRv6 networks", Work in
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Progress, Internet-Draft, draft-filsfils-spring-path-
tracing-05, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-filsfils-
spring-path-tracing-05>.
[I-D.ietf-ippm-ioam-ipv6-options]
Bhandari, S. and F. Brockners, "In-situ OAM IPv6 Options",
Work in Progress, Internet-Draft, draft-ietf-ippm-ioam-
ipv6-options-12, 7 May 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
ioam-ipv6-options-12>.
[I-D.kumar-ippm-ifa]
Kumar, J., Anubolu, S., Lemon, J., Manur, R., Holbrook,
H., Ghanwani, A., Cai, D., Ou, H., Li, Y., and X. Wang,
"Inband Flow Analyzer", Work in Progress, Internet-Draft,
draft-kumar-ippm-ifa-07, 7 September 2023,
<https://datatracker.ietf.org/doc/html/draft-kumar-ippm-
ifa-07>.
[I-D.spiegel-ippm-ioam-rawexport]
Spiegel, M., Brockners, F., Bhandari, S., and R.
Sivakolundu, "In-situ OAM raw data export with IPFIX",
Work in Progress, Internet-Draft, draft-spiegel-ippm-ioam-
rawexport-06, 21 February 2022,
<https://datatracker.ietf.org/doc/html/draft-spiegel-ippm-
ioam-rawexport-06>.
[I-D.wang-ippm-stamp-hbh-extensions]
Zhou, T., Fioccola, G., Mishra, G. S., Yang, H., and C.
Liu, "Simple Two-way Active Measurement Protocol (STAMP)
Extensions for Hop- by-Hop Data Collection", Work in
Progress, Internet-Draft, draft-wang-ippm-stamp-hbh-
extensions-06, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-wang-ippm-
stamp-hbh-extensions-06>.
Appendix A. New ICMPv6 Type vs. New Code
One of the issues that was discussed in the development of this
document is whether ICMPv6 Loopback Request and Reply should be
identified based on the ICMPv6 type, or based on the code value. The
first approach, which is used throughout this document, is to define
new type values for Loopback Request and Loopback Reply. The second
approach is to reuse the Echo Request and Reply type values, but to
define new code values that identify the Loopback messages.
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Notably, the behavior of ICMPv6 as defined in [RFC4443] is well
defined when receiving an unknown type, but the behavior when
receiving an unknown code in an Echo message has not been defined.
Therefore, this behavior varies between different implementations.
For example, in Debian distributions an Echo Reply is sent with the
same code that was received in the Echo Request, regardless of
whether the code value is known. In FreeBSD, on the other hand, if
an Echo Request is received with an unknown code it is ignored. Due
to this ambiguity in [RFC4443] it is not possible to use Echo
messages with a new code value, since existing implementations may
behave in an unpredictable manner.
The current document therefore defines new type values for ICMPv6
Loopback messages.
Authors' Addresses
Tal Mizrahi
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: tal.mizrahi.phd@gmail.com
Tianran Zhou
Huawei
156 Beiqing Rd.
Beijing
100095
China
Email: zhoutianran@huawei.com
Shahar Belkar
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: shahar.belkar@huawei.com
Reuven Cohen
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: reuven.cohen@huawei.com
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Justin Iurman
Universite de Liege
10, Allee de la decouverte (B28)
4000 Sart-Tilman
Belgium
Email: justin.iurman@uliege.be
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