Network Working Group M. Sivakumar
Internet-Draft Juniper Networks
Updates: 3376, 3810 (if approved) S. Venaas
Intended status: Standards Track Cisco Systems, Inc.
Expires: July 25, 2021 Z. Zhang
ZTE Corporation
H. Asaeda
NICT
January 21, 2021
IGMPv3/MLDv2 Message Extension
draft-ietf-pim-igmp-mld-extension-04
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 July 25, 2021.
Copyright Notice
Copyright (c) 2021 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
Sivakumar, et al. Expires July 25, 2021 [Page 1]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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 . . . . . . . . . . . . . . 3
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. Processing the extension . . . . . . . . . . . . . . . . . . 8
5. Applicability and backwards compatibility . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 11
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].
When this extension mechanism is used, it replaces the Additional
Data section defined in IGMPv3/MLDv2 for TLVs.
Additional Data is defined for query messages in IGMPv3 [RFC3376]
Section 4.1.10 and MLDv2 [RFC3810] Section 5.1.12, and for report
messages in IGMPv3 [RFC3376] Section 4.2.11 and MLDv2 [RFC3810]
Section 5.2.11.
One such TLV is being defined for use in BIER IGMP/MLD overlays
[I-D.ietf-bier-mld]. This TLV provides BIER specific information
that only will be processed by BIER routers.
Sivakumar, et al. Expires July 25, 2021 [Page 2]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Extension Format
A previously reserved bit in the IGMPv3 and MLDv2 headers is used to
indicate whether this extension is used. 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
Extension Type: 2 octets. This identifies a particular Extension
Type as defined in the IGMP/MLD Extension Type Registry. If this
is not the first TLV, it will follow immediately after the end of
the previous Extension Value field, or immediately after the
previous Extension Length field if the previous Extension Length
was zero. There is no alignment or padding.
Sivakumar, et al. Expires July 25, 2021 [Page 3]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
Extension Length: 2 octets. This specifies the length in octets
of the following Extension Value field. The length may be zero if
no value is needed.
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.
IGMPv3 and MLDv2 messages are defined so that they can fit within the
network MTU, in order to avoid fragmentation. When this extension
mechanism is used, the number of Group Records in each Report message
should be kept small enough that the entire message, including any
extension TLVs can fit within the network MTU.
3.1. Multicast Listener Query Extension
The MLD query format with extension is shown below. The E-bit MUST
be set to 1 to indicate that the extension is present. Otherwise it
MUST be 0.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Multicast Address *
| |
* *
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Resv|S| QRV | QQIC | Number of Sources (N) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
* *
| |
* Source Address [1] *
| |
* *
| |
+- -+
Sivakumar, et al. Expires July 25, 2021 [Page 4]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
| |
* *
| |
* 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 MUST
be set to 1 to indicate that the extension is present. Otherwise it
MUST be 0.
Sivakumar, et al. Expires July 25, 2021 [Page 5]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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
MUST be set to 1 to indicate that the extension is present.
Otherwise it MUST be 0.
Sivakumar, et al. Expires July 25, 2021 [Page 6]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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
MUST be set to 1 to indicate that the extension is present.
Otherwise it MUST be 0.
Sivakumar, et al. Expires July 25, 2021 [Page 7]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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. Processing the extension
How to validate and process a specific type will be defined in the
respective type specifications, but prior to validating and
processing each of the types, the following general validation MUST
be done.
First one MUST check that the E-bit is set, otherwise this
specification does not apply. There MUST be no data in the IP
payload after the last TLV. To check this, one will need to walk
through each of The TLVs until there are less than four octets left
in the IP payload. If there are any octets left, validation failed.
Sivakumar, et al. Expires July 25, 2021 [Page 8]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
The walk also stops and validation fails if a TLV has a length
exceeding the remainder of the IP payload. For this validation, one
only examines the content of the Extension Length fields.
If the validation failed, the entire Additional Data field MUST be
ignored as specified in IGMPv3 [RFC3376] and MLDv2 [RFC3810].
If the validation succeeded, one will proceed examining each of the
specified types and perform validation and processing of the
respective types. Unsupported types MUST be ignored; type validation
and processing proceeds as if they were not present.
5. Applicability and backwards compatibility
IGMP and MLD implementations, host implementations in particular,
rarely change, and it is 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. Due to
this, defining extensions should not be taken lightly, and it is
crucial to consider backwards compatibility.
Implementations that do not support this extension mechanism will
simply ignore the extension, provided they are compliant with IGMPv3
and MLDv2 RFCs, which specify that additional data must be ignored,
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 none of the extension types in an IGMP/MLD message. If they
support at least one of the types, they will 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 to 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
Sivakumar, et al. Expires July 25, 2021 [Page 9]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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 hosts 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.
This document defines an extension mechanism only for IGMPv3 and
MLDv2. Hence this mechanism would not apply if hosts or routers send
older version message.
6. Security Considerations
This document extends IGMP and MLD message formats, allowing for a
variable number of TLVs. Implementations must take care when parsing
the TLVs to not exceed the packet boundary, an attacker could
intentionally specify a TLV with a length exceeding the boundary.
An implementation could add a large number of minimal TLVs in a
message to increase the cost of processing the message to magnify a
Denial of Service attack.
The respective types defined using this extension may impact security
and this MUST be considered as part of the respective specifications.
7. 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
Management Protocol (IGMP) Type Numbers" section. The initial
content of the registry should be as below.
Type Length Name Reference
--------------------------------------------------------------
8. Acknowledgements
The authors thank Ian Duncan, Leonard Giuliano, Jake Holland and
Zhaohui Zhang for reviewing the document and providing valuable
feedback.
Sivakumar, et al. Expires July 25, 2021 [Page 10]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
9. References
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,
<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>.
9.2. 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>.
Authors' Addresses
Sivakumar, et al. Expires July 25, 2021 [Page 11]
Internet-Draft IGMPv3/MLDv2 message extension January 2021
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
Sivakumar, et al. Expires July 25, 2021 [Page 12]
