IGMPv3/MLDv2 Message Extension
draft-ietf-pim-igmp-mld-extension-02
The information below is for an old version of the document.
| Document | Type |
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|
|---|---|---|---|
| Authors | Mahesh Sivakumar , Stig Venaas , Zheng Zhang , Hitoshi Asaeda | ||
| Last updated | 2020-11-02 (Latest revision 2020-07-12) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-pim-igmp-mld-extension-02
Network Working Group M. Sivakumar
Internet-Draft Juniper Networks
Updates: 3376, 3810 (if approved) S. Venaas
Intended status: Standards Track Cisco Systems, Inc.
Expires: May 6, 2021 Z. Zhang
ZTE Corporation
H. Asaeda
NICT
November 2, 2020
IGMPv3/MLDv2 Message Extension
draft-ietf-pim-igmp-mld-extension-02
Abstract
IGMP and MLD protocols are extensible, but no extensions have been
defined so far. This document provides a well-defined way of
extending IGMP and MLD, using a list of TLVs (Type, Length and
Value).
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 May 6, 2021.
Copyright Notice
Copyright (c) 2020 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
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to this document. Code Components extracted from this document must
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 . . . . . . . . . . . . . . 2
3. Extension Format . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Multicast Listener Query Extension . . . . . . . . . . . 4
3.2. Version 2 Multicast Listener Report Extension . . . . . . 5
3.3. IGMP Membership Query Extension . . . . . . . . . . . . . 6
3.4. IGMP Version 3 Membership Report Extension . . . . . . . 7
4. Applicability and backwards compatibility . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
In this document, we describe a generic method to extend IGMPv3
[RFC3376] and MLDv2 [RFC3810] messages to accommodate information
other than what is contained in the current message formats. This is
done by allowing a list of TLVs (Type, Length and Value) to be used
in the Additional Data part of IGMPv3 and MLDv2 messages. This
document defines a registry for such TLVs, while other documents will
define the specific types and their values, and their semantics. The
extension would only be used when at least one TLV is to be added to
the message. This extension also applies to the lightweight versions
of IGMPv3 and MLDv2 as defined in [RFC5790].
The extension will be part of additional data as mentioned in
[RFC3810] Section 5.1.12 (resp. [RFC3376] Section 4.1.10) for query
messages and [RFC3810] Section 5.2.12 (resp. [RFC3376]
Section 4.2.11) for report messages.
One such TLV is being defined in [I-D.ietf-bier-mld]
2. Conventions used in this document
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
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14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Extension Format
A previously reserved bit in the IGMPv2 and MLDv2 headers is used to
indicate whether this extension is used. It is set to 1 if it is
used, otherwise 0. When this extension is used, the Additional Data
of IGMPv3 and MLDv2 messages would be formatted as follows. Note
that this format contains a variable number of TLVs. It MUST contain
at least one TLV.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Total Extension Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Type 1 | Extension Length 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Value 1 |
. . .
. . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Type 2 | Extension Length 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Value 2 |
. . .
. . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Type n | Extension Length n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension Value n |
. . .
. . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extension Format
Reserved: 2 octets. Reserved. MUST be set to 0. MUST be ignored
when received.
Total Extension Length: 2 octets. The remaining length of the
extension. This value MUST be equal to ((2 + 2) * n) + Extension
Length 1 + Extension Length 2 + ... Extension Length n. That is,
it is the sum of the lenghts of all the TLVs, including the type
field (2 octets), and the length field (2 octets) of each TLV.
The total number of octets used by the extension is the value of
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this field plus 4 (including the 2 octets Reserved field and the 2
octets of this field).
Extension Type: 2 octets. This identifies a particular Extension
Type as defined in the IGMP/MLD Extension Type Registry.
Extension Length: 2 octets. This specifies the length in octets
of the following Extension Value field.
Extension Value: This field contains the value. The length and
the contents of this field is according to the specification of
the Extension Type as defined in the IGMP/MLD Extension Type
Registry. The length MUST be as specified in the Extension Length
field.
Note that there may be additional data following this extension. The
Total Extension Length field would indicate where this extension
ends, and the additional data starts. Also, there is a possibility
that an implementation uses the Additional Data part of IGMP/MLD
messages, but not according to this extension scheme. When a message
is received, it MUST be verified that the Total Extension Length is
equal to ((2 + 2) * n) + Extension Length 1 + Extension Length 2 +
... Extension Length n, where n is the number of TLVs. Note that the
value of n is not known ahead of time. An implementation would walk
through the TLVs and add the 4 octet overhead and the length of each
TLV, until the sum is larger or equal to the Total Extension Length,
or until the end of the IGMP/MLD message, whichever happens first.
Any additional data after this MUST be ignored, except the data MUST
be included in checksum computations. If the sum is not equal to the
Total Extension Length, then it is assumed that this extension is not
being used, and this specification does not apply.
3.1. Multicast Listener Query Extension
The MLD query format with extension is shown below. The E-bit is set
to 1 to indicate that the extension is present.
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 = 130 | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Response Code | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
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* Multicast Address *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Resv|S| QRV | QQIC | Number of Sources (N) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Source Address [1] *
| |
* *
| |
+- -+
| |
* *
| |
* Source Address [2] *
| |
* *
| |
+- . -+
. . .
. . .
+- -+
| |
* *
| |
* Source Address [N] *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MLD Query Extension
3.2. Version 2 Multicast Listener Report Extension
The MLD report format with extension is shown below. The E-bit is
set to 1 to indicate that the extension is present.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 143 | Reserved | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Reserved |Nr of Mcast Address Records (M)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [1] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [2] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Multicast Address Record [M] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MLD Report Extension
3.3. IGMP Membership Query Extension
The IGMP query format with the extension is shown below. The E-bit
is set to 1 to indicate that the extension is present.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x11 | Max Resp Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Resv|S| QRV | QQIC | Number of Sources (N) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address [1] |
+- -+
| Source Address [2] |
+- . -+
. . .
. . .
+- -+
| Source Address [N] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: IGMP Query Extension
3.4. IGMP Version 3 Membership Report Extension
The IGMP report format with the extension is shown below. The E-bit
is set to 1 to indicate that the extension is present.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x22 | Reserved | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Reserved | Number of Group Records (M) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [1] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [2] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [M] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extension |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IGMP Report Extension
4. Applicability and backwards compatibility
IGMP and MLD implementations, host implementations in particular,
rarely change, and it expected to take a long time for them to
support this extension mechanism. Also as new extensions are
defined, it may take a long time before they are supported.
Implementations that do not support this extension mechanism will
simply ignore the extension, provided they are compliant with IGMPv3
and MLDv2 RFCs, and behave as if the extension is not present.
Implementations that support this extension MUST behave as if it is
not present if they support non of the extension types in an IGMP/MLD
message. If they support at least one of the types, they will
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process the supported types according to the respective type
specifications, and ignore any unsupported types.
It is possible that a new extension type only applies to queries, or
only reports, or there may be other specific conditions for when it
is to be used. A document defining a new type MUST specify clearly
under what conditions the new type should be used, including for
which message types. It MUST also be considered what the behavior
should be if a message is not used in the defined manner, e.g., if it
is present in a query message, when it was only expected to be used
in reports.
When defining new types, care must be taken to ensure that nodes that
support the type can co-exist with nodes that don't, on the same
subnet. There could be multiple routers where only some support the
extension, or multiple hosts where only some support the extension.
Or a router may support it and none of the hosts, or all hosts may
support it, but none of the routers. With multiple types being used,
it must also be considered that some hosts or routers may only
support some of the types, and potentially one node might support
only one type, and another node only another type.
Documents defining new types MUST have security considerations
relevant to the new types. They MUST also in addition to defining
the behavior of host and routers supporting the new types, consider
compatibility with hosts and routers on the same subnet that do not
support the new types. Further, they MUST consider whether there are
any dependencies or restrictions on combinations between the new
types and any pre-existing types.
The extension mechanism do not support IGMPv1, IGMPv2 and MLDv1. As
nodes may send older version message, they would also not be able to
send messages using this extension.
5. Security Considerations
This document extends MLD (resp. IGMP) message formats. As such,
there is no impact on security or changes to the considerations in
[RFC3810] and [RFC3376]. The respective types defined using this
extension may impact security and MUST be considered as part of the
respective specifications.
6. IANA Considerations
A new registry called "IGMP/MLD Extension Types" should be created
with registration procedure "IETF Review" as defined in [RFC8126]
with this document as a reference. The registry should be common for
IGMP and MLD and can perhaps be added to the "Internet Group
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Management Protocol (IGMP) Type Numbers" section. The initial
content of the registry should be as below.
Type Length Name Reference
--------------------------------------------------------------
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, DOI 10.17487/RFC3376, October 2002,
<https://www.rfc-editor.org/info/rfc3376>.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
DOI 10.17487/RFC3810, June 2004,
<https://www.rfc-editor.org/info/rfc3810>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
7.2. Informative References
[I-D.ietf-bier-mld]
Pfister, P., Wijnands, I., Venaas, S., Wang, C., Zhang,
Z., and M. Stenberg, "BIER Ingress Multicast Flow Overlay
using Multicast Listener Discovery Protocols", draft-ietf-
bier-mld-04 (work in progress), March 2020.
[RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet
Group Management Protocol Version 3 (IGMPv3) and Multicast
Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790,
DOI 10.17487/RFC5790, February 2010,
<https://www.rfc-editor.org/info/rfc5790>.
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Authors' Addresses
Mahesh Sivakumar
Juniper Networks
64 Butler St
Milpitas CA 95035
USA
Email: sivakumar.mahesh@gmail.com
Stig Venaas
Cisco Systems, Inc.
Tasman Drive
San Jose CA 95134
USA
Email: stig@cisco.com
Zheng(Sandy) Zhang
ZTE Corporation
No. 50 Software Ave, Yuhuatai District
Nanjing 210000
China
Email: zhang.zheng@zte.com.cn
Hitoshi Asaeda
National Institute of Information and
Communications Technology
4-2-1 Nukui-Kitamachi
Koganei, Tokyo 184-8795
Japan
Email: asaeda@nict.go.jp
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