Internet DRAFT - draft-ietf-bier-ipv6-requirements
draft-ietf-bier-ipv6-requirements
Network Working Group M. McBride
Internet-Draft Futurewei
Intended status: Informational J. Xie
Expires: April 1, 2021 X. Geng
S. Dhanaraj
Huawei
R. Asati
Cisco
Y. Zhu
China Telecom
G. Mishra
Verizon Inc.
Z. Zhang
Juniper
September 28, 2020
BIER IPv6 Requirements
draft-ietf-bier-ipv6-requirements-09
Abstract
There have been several proposed solutions with BIER being used in
IPv6. But there hasn't been a document which describes the problem
and lists the requirements. The goal of this document is to describe
the general BIER IPv6 encapsulation problem and detail solution
requirements, thereby assisting the working group in the development
of acceptable solutions.
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
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Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 1, 2021.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Mandatory Requirements . . . . . . . . . . . . . . . . . 4
3.1.1. Support various L2 link types . . . . . . . . . . . . 4
3.1.2. Support BIER architecture . . . . . . . . . . . . . . 4
3.1.3. Support deployment with Non-BFR routers . . . . . . . 4
3.1.4. Support OAM . . . . . . . . . . . . . . . . . . . . . 5
3.2. Optional Requirements . . . . . . . . . . . . . . . . . . 5
3.2.1. Support Fragmentation . . . . . . . . . . . . . . . . 5
3.2.2. Support IPSEC ESP . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides optimal multicast forwarding, without requiring
intermediate routers to maintain per-flow state, through the use of a
multicast-specific BIER header. [RFC8296] defines two types of BIER
encapsulation: one is BIER MPLS encapsulation for MPLS environments,
the other is non-MPLS BIER encapsulation to run without MPLS. This
document describes non-MPLS BIER encapsulation in IPv6 environments.
We explain the requirements of transporting multicast flow overlay
payload through an IPv6 network underlay using BIER. The solutions
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may use IPv6 forwarding plane and may include IPv6 encapsulation and/
or generic IPv6 tunnelling.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology
o BIER: Bit Index Explicit Replication. Provides optimal multicast
forwarding through adding a BIER header and removing state in
intermediate routers.
2. Problem Statement
The problem is how to transport multicast packets, with non-MPLS BIER
encapsulation, in an IPv6 environment. We need to determine where to
put the BIER header in this IPv6 environment. With IPv6
encapsulation being increasingly used for unicast services, such as
VPN or L2VPN, it may be desirable to have IPv6 encapsulation also
used in BIER deployments for multicast services such as MVPN. It may
also be desirable to not use IPv6 encapsulation except when IPv6
tunneling (native or GRE/UDP-like) is used to transport BIER packets
over BIER-incapable routers.
Below is a simple scenario that needs BIER IPv6-based forwarding:
+--------------------------------------------+
| |
| +------+
| | BFER |
+------+ +-------+ +-----+ +------+
| BFIR | |Non-BFR| | BFR | |
+------+ +-------+ +-----+ +------+
| | BFER |
| IPv6 Network +------+
| |
+--------------------------------------------+
This scenario depicts the need to replicate BIER packets from a BFIR
to BFERs across an IPv6 Service Provider core. Inside the IPv6
network, the BIER header is used to direct the packet from one BFR to
the next BFRs, and either a IPv6 header or an L2/tunnel header is
used to provide reachability between BFRs. The IPv6 environment may
include a variety of link types, may be entirely IPv6, or may be dual
stack. There may be cases where not all routers are BFR capable in
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the IPv6 environment but still want to deploy BIER. Regardless of
the environment, the problem is to deploy BIER, with non-MPLS BIER
encapsulation, in an IPv6 network.
3. Requirements
There are several suggested requirements for BIER IPv6 solutions.
In this document, the requirements are divided into two levels:
Mandatory and Optional. The requirement levels are determined based
on the following factors:
If the requirement is required for a feature that is likely to be
a potential deployment, the requirement level will be considered
mandatory.
If the impact of not implementing the requirement may block BIER
from been deployed, the requirement level will be considered
mandatory.
3.1. Mandatory Requirements
Considering that these mandatory requirements are all well-known to
the working group, and practical in normal deployment, they will be
listed without a detailed description.
3.1.1. Support various L2 link types
The solution should support various kinds of L2 data link types.
3.1.2. Support BIER architecture
The solution must support the BIER architecture.
Supporting different multicast flow overlays, multiple sub-domains,
multi-topologies, multiple sets, multiple Bit String Lengths, and
deterministic ECMP are considered essential functions of BIER and
need to be supported.
3.1.3. Support deployment with Non-BFR routers
The solution must support deployments with BIER-incapable routers.
This is beneficial to the deployment of BIER, especially in early
deployments when some routers do not support BIER forwarding but
support IPv6 forwarding.
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3.1.4. Support OAM
BIER OAM tools like [I-D.ietf-bier-ping] and [I-D.ietf-bier-pmmm-oam]
should be supported, either directly using existing methods, or by
specifying a new method for the same functionality. They are likely
to be needed in normal BIER deployment for diagnostics.
3.2. Optional Requirements
The requirements in this section are listed as optional, and each
requirement is explained with a detailed scenario. Note that
fragmentation and IPSEC ESP are not BIER functions, they are provided
by the upper IP layer.
3.2.1. Support Fragmentation
There are some cases where the Fragmentation/Assembly function is
needed for BIER to work in an IPv6 network.
For example, a customer IPv6 multicast packet may be 1280 bytes and
is required to be transported through an IPv6 network using BIER.
Every link of the IPv6 network is no less than the requisite 1280
bytes [RFC8200], but the size of the payload that can be encapsulated
in BIER (BIER-MTU) is less than 1280 bytes. In this case, it is not
the appropriate action for a BFIR to drop the packet and advertise an
MTU to the source [RFC8296]. Instead, some transport mechanism needs
to provide the fragmentation and assembly function.
3.2.2. Support IPSEC ESP
There are some cases where the IPSEC ESP function may be needed to
transport c-multicast packets through an IPv6 network with
confidentiality using BIER technology.
A service provider may want to provide additional security SLA to its
customer to ensure that the unencrypted c-multicast packet is not
altered in the service provider's network. In this case, if the BIER
technology is preferred for the multicast service, BIER with IPSEC
ESP support may be a candidate solution. On the other hand, the
traffic protection may be better provided via IPSEC or MACSEC at
multicast flow overlay over and beyond the BIER domain.
4. IANA Considerations
Some BIER IPv6 encapsulation proposals do not require any action from
IANA while other proposals require new IPv6 Option codepoints from
IPv6 sub-registries, new "Next header" values, or require new IP
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Protocol codes. This document, however, does not require anything
from IANA.
5. Security Considerations
There are no security issues introduced by this draft.
6. Acknowledgement
Thanks to Eric Rosen for his listed set of initial requirements on
the BIER WG mailing list.
7. Normative References
[I-D.ietf-bier-ping]
Nainar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M.,
and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier-
ping-07 (work in progress), May 2020.
[I-D.ietf-bier-pmmm-oam]
Mirsky, G., Zheng, L., Chen, M., and G. Fioccola,
"Performance Measurement (PM) with Marking Method in Bit
Index Explicit Replication (BIER) Layer", draft-ietf-bier-
pmmm-oam-08 (work in progress), May 2020.
[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>.
[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>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
[RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
for Bit Index Explicit Replication (BIER) in MPLS and Non-
MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
2018, <https://www.rfc-editor.org/info/rfc8296>.
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Authors' Addresses
Mike McBride
Futurewei
Email: michael.mcbride@futurewei.com
Jingrong Xie
Huawei
Email: xiejingrong@huawei.com
Xuesong Geng
Huawei
Email: gengxuesong@huawei.com
Senthil Dhanaraj
Huawei
Email: senthil.dhanaraj@huawei.com
Rajiv Asati
Cisco
Email: rajiva@cisco.com
Yongqing Zhu
China Telecom
Email: zhuyq8@chinatelecom.cn
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
Zhaohui Zhang
Juniper
Email: zzhang@juniper.net
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