Internet DRAFT - draft-ietf-bier-bierin6
draft-ietf-bier-bierin6
BIER Z. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track Z. Zhang, Ed.
Expires: 21 March 2024 Juniper Networks
I. Wijnands
Individual
M. Mishra
Cisco Systems
H. Bidgoli
Nokia
G. Mishra
Verizon
18 September 2023
Supporting BIER in IPv6 Networks (BIERin6)
draft-ietf-bier-bierin6-08
Abstract
BIER is a multicast forwarding architecture that does not require
per-flow state inside the network yet still provides optimal
replication. This document describes how the existing BIER
encapsulation specified in RFC 8296 works in a non-MPLS IPv6 network,
which is referred to as BIERin6. Specifically, like in an IPv4
network, BIER can work over L2 links directly or over tunnels. In
case of IPv6 tunneling, a new IP "Next Header" type is to be assigned
for BIER.
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.
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/.
Zhang, et al. Expires 21 March 2024 [Page 1]
Internet-Draft BIERin6 September 2023
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 21 March 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
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
1.1. BIER over L2/Tunnels . . . . . . . . . . . . . . . . . . 3
1.2. Considerations of Requirements for BIER in IPv6
Networks . . . . . . . . . . . . . . . . . . . . . . . . 4
2. IPv6 Header . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6 Encapsulation Advertisement . . . . . . . . . . . . . . 6
4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Inter-area prefix redistribution . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
BIER [RFC8279] is a multicast forwarding architecture that does not
require per-flow state inside the network yet still provides optimal
replication.
Zhang, et al. Expires 21 March 2024 [Page 2]
Internet-Draft BIERin6 September 2023
BIER forwarding with MPLS is IPv4/IPv6 agnostic. This document
describes how BIER works in a non-MPLS IPv6 [RFC8200] environment
using non-MPLS BIER encapsulation [RFC8296], with optional procedures
specified for IPv6 specific features.
This document uses terminology defined in [RFC8279] and [RFC8296].
1.1. BIER over L2/Tunnels
[RFC8296] defines the BIER encapsulation format for MPLS and non-MPLS
data planes. With a non-MPLS data plane, a BIER packet is the
payload of an "outer" encapsulation, which could be a L2 link or a
tunnel. The outer encapsulation has a "next header" field that is
set to a value for "non-MPLS BIER". This "BIER over L2/Tunnel" model
can be used as is in an IPv6 non-mpls environment, and is referred to
as BIERin6.
If a BFR needs to tunnel BIER packets to another BFR, e.g. per
[RFC8279] Section 6.9, while any type of tunnel will work, for best
efficiency native IPv6 encapsulation can be used with the destination
address being the downstream BFR and the Next Header field set to a
to-be-assigned value for BIER.
+---------------+------------------------
| IPv6 header | BIER header + data
| |
| Next Header = |
| BIER |
+---------------+------------------------
Between two directly connected BFRs, a BIER header can directly
follow link layer header, e.g., an Ethernet header (with the
Ethertype set to 0xAB37). Optionally, IPv6 encapsulation can be used
even between directly connected BFRs (i.e. one-hop IPv6 tunneling) in
the following two cases:
* An operator mandates all traffic to be carried in IPv6.
* A BFR does not have BIER support in its "fast forwarding path" and
relies on "slow/software forwarding path", e.g. in IPv6 Home
Networking [RFC7368] where high throughput multicast forwarding
performance is not critical.
Zhang, et al. Expires 21 March 2024 [Page 3]
Internet-Draft BIERin6 September 2023
1.2. Considerations of Requirements for BIER in IPv6 Networks
[I-D.ietf-bier-ipv6-requirements] lists mandatory and optional
requirements for BIER in IPv6 Networks. As a solution based on the
BIER over L2/tunnel model [RFC8296], BIERin6 satisfies all the
mandatory requirements.
For the two optional requirements for fragmentation and Encapsulating
Security Payload (ESP), they can be satisfied by one of two ways:
* IPv6 based fragmentation/ESP: a BFIR encapsulates the payload in
IPv6 with fragmentation and/or ESP header, and then the IPv6
packets are treated as BIER payload.
* Generic Fragmentation/ESP
[I-D.zzhang-intarea-generic-delivery-functions]: a BFIR does
generic fragmentation and/or ESP (without using IPv6
encapsulation) and the resulting packets are treated as BIER
payload.
BIERin6 can support SRv6 based overlay services (e.g. MVPN/EVPN)
with one of the following methods:
* An ingress PE (which is a BFIR) can encapsulate customer packets
with an IPv6 header (with optional fragmentation and ESP extension
headers). Any SRv6-based scheme can by used for service
delimiting.
* Alternatively, since only the IPv6 address in the above-mentioned
outer IPv6 header is used for service delimiting purpose, a new
value can be assigned for the Proto field in the BIER header to
indicate that an SRv6 Service SID [RFC9252] (instead of an entire
IPv6 header) is added between the BIER header and original
payload. For example, an End.DT2/4/6 service SID could be used to
route the original payload in a corresponding VRF.
The details of fagmentation/ESP support and service delimitation are
all outside the scope of this document.
BIERin6 being a solution based on [RFC8279] and [RFC8296], ECMP is
inherently supported by BFRs using the the 20-bit entropy field in
the BIER header for the load balancing hash. When a BIER packet is
transported over an IPv6 tunnel, the entropy value is copied into the
20-bit IPv6 Flow Label [RFC6437], so that routers along the tunnel
can do ECMP based on Flow Labels (instead of hashing based on 5-tuple
of an IP packet). For a router along the tunnel doing deep packet
inspection for ECMP purpose, if it understands BIER header it can go
past the BIER header to look for the 5-tuple input key to a hash
Zhang, et al. Expires 21 March 2024 [Page 4]
Internet-Draft BIERin6 September 2023
function. Otherwise, it stops at the BIER header. In either case
the router will not mistake the BIER header as an IP header so no
misordering should happen.
BIER has its own OAM functions independent of those related to the
underlying links or tunnels. With BIERin6 following the "BIER over
L2/tunnel" model, IPv6 OAM function and BIER OAM functions are used
independently for their own purposes.
Specifically, BIERin6 works with all of the following OAM methods, or
any future methods that are based on the "BIER over L2/tunnel" model:
* BIER OAM specified in [I-D.ietf-bier-ping]
* BIER BFD specified in [I-D.ietf-bier-bfd]
* BIER Performance Measurement specified in [I-D.ietf-bier-pmmm-oam]
* BIER Path Maximum Transmission Unit Discovery specified in
[I-D.ietf-bier-path-mtu-discovery]
* BIER IOAM specified in [I-D.xzlnp-bier-ioam]
2. IPv6 Header
If IPv6 encapsulation is used to tunnel BIER packets (whether to a
direct or indirect BIER neighbor), the Next Header field in the IPv6
Header (if there are no extension headers), or the Next Header field
in the last extension header is set to TBD, indicating that the
payload is a BIER packet.
If the neighbor is directly connected, The destination address in
IPv6 header SHOULD be the neighbor's link-local address on this
router's outgoing interface. The source destination address SHOULD
be this router's link-local address on the outgoing interface, and
the TTL MUST be set to 1.
If the neighbor is not directly connected, the destination address
SHOULD be the BIER prefix of the BFR neighbor. The source address
SHOULD be this router's BIER prefix, and the TTL MUST be large enough
to get the packet to the BFR neighbor.
The "Flow label" field in the IPv6 packet SHOULD be copied from the
entropy field in the BIER encapsulation.
Zhang, et al. Expires 21 March 2024 [Page 5]
Internet-Draft BIERin6 September 2023
3. BIER Header
The BIER header MUST be encoded per Section 2.2 of [RFC8296].
The BIFT-id is either encoded per
[I-D.ietf-bier-non-mpls-bift-encoding] or per advertised by BFRs, as
specified in [I-D.ietf-bier-lsr-non-mpls-extensions].
4. IPv6 Encapsulation Advertisement
When IPv6 encapsulation is not required between directly connected
BFRs, no signaling in addition to that specified in
[I-D.ietf-bier-lsr-non-mpls-extensions] is needed.
Otherwise, a node that requires IPv6 encapsulation MUST advertise the
BIER IPv6 encapsulation sub-sub-sub-TLV/sub-sub-TLV according to
local configuration or policy in the BIER domain to request other
BFRs to always use IPv6 encapsulation.
4.1. Format
The BIER IPv6 Encapsulation is a new sub-sub-TLV of OSPFv3 BIER non-
MPLS Encapsulation sub-TLV, and a new sub-sub-sub-TLV of ISIS BIER
non-MPLS Encapsulation sub-sub-TLV as per
[I-D.ietf-bier-lsr-non-mpls-extensions].
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Type: For OSPF, value TBD1 indicates it is the IPv6 Encapsulation
sub-TLV. For ISIS, value TBD2 indicates it is the IPv6
encapsulation sub-sub-TLV.
* Length: 0.
4.2. Inter-area prefix redistribution
When BFR-prefixes are advertised across IGP areas per
[I-D.ietf-bier-lsr-non-mpls-extensions] or redistributed across
protocol boundaries per [I-D.ietf-bier-prefix-redistribute], the BIER
IPv6 encapsulation sub-sub-TLV or sub-sub-sub-TLV MAY be re-
advertised/re-distributed as well.
Zhang, et al. Expires 21 March 2024 [Page 6]
Internet-Draft BIERin6 September 2023
5. IANA Considerations
IANA is requested to assign a "BIER" type for "Next Header" in the
"Assigned Internet Protocol Numbers" registry.
IANA is requested to assign a "BIER IPv6 encapsulation Sub-sub-TLV"
type in the "OSPFv3 BIER non-MPLS Encapsulation sub-TLV" Registry.
IANA is requested to assign a "BIER IPv6 encapsulation Sub-sub-sub-
TLV" type in the "IS-IS BIER non-MPLS Encapsulation sub-sub-TLV"
Registry.
IANA is requested to allocate a value "SRv6 Service" from "BIER Next
Protocol Identifiers" registry to indicate that BIER payload starts
with an SRv6 Service SID.
6. Security Considerations
General IPv6 and BIER security considerations apply.
7. Acknowledgement
The authors would like to thank Tony Przygienda, Nagendra Kumar for
their review and valuable comments.
8. References
8.1. Normative References
[I-D.ietf-bier-lsr-non-mpls-extensions]
Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, Z.
J., and J. Xie, "LSR Extensions for BIER non-MPLS
Encapsulation", Work in Progress, Internet-Draft, draft-
ietf-bier-lsr-non-mpls-extensions-01, 19 September 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
lsr-non-mpls-extensions-01>.
[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>.
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437,
DOI 10.17487/RFC6437, November 2011,
<https://www.rfc-editor.org/info/rfc6437>.
Zhang, et al. Expires 21 March 2024 [Page 7]
Internet-Draft BIERin6 September 2023
[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>.
[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>.
[RFC9252] Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene,
B., Zhuang, S., and J. Rabadan, "BGP Overlay Services
Based on Segment Routing over IPv6 (SRv6)", RFC 9252,
DOI 10.17487/RFC9252, July 2022,
<https://www.rfc-editor.org/info/rfc9252>.
8.2. Informative References
[I-D.ietf-bier-bfd]
Xiong, Q., Mirsky, G., hu, F., and C. Liu, "BIER BFD",
Work in Progress, Internet-Draft, draft-ietf-bier-bfd-04,
11 September 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-bier-bfd-04>.
[I-D.ietf-bier-ipv6-requirements]
McBride, M., Xie, J., Geng, X., Dhanaraj, S., Asati, R.,
Zhu, Y., Mishra, G. S., and Z. J. Zhang, "BIER IPv6
Requirements", Work in Progress, Internet-Draft, draft-
ietf-bier-ipv6-requirements-09, 28 September 2020,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
ipv6-requirements-09>.
Zhang, et al. Expires 21 March 2024 [Page 8]
Internet-Draft BIERin6 September 2023
[I-D.ietf-bier-non-mpls-bift-encoding]
Wijnands, I., Mishra, M. P., Xu, X., and H. Bidgoli, "An
Optional Encoding of the BIFT-id Field in the non-MPLS
BIER Encapsulation", Work in Progress, Internet-Draft,
draft-ietf-bier-non-mpls-bift-encoding-04, 30 May 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
non-mpls-bift-encoding-04>.
[I-D.ietf-bier-path-mtu-discovery]
Mirsky, G., Przygienda, T., and A. Dolganow, "Path Maximum
Transmission Unit Discovery (PMTUD) for Bit Index Explicit
Replication (BIER) Layer", Work in Progress, Internet-
Draft, draft-ietf-bier-path-mtu-discovery-14, 26 March
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
bier-path-mtu-discovery-14>.
[I-D.ietf-bier-ping]
Nainar, N. K., Pignataro, C., Chen, M., and G. Mirsky,
"BIER Ping and Trace", Work in Progress, Internet-Draft,
draft-ietf-bier-ping-12, 29 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
ping-12>.
[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", Work in
Progress, Internet-Draft, draft-ietf-bier-pmmm-oam-14, 10
July 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-bier-pmmm-oam-14>.
[I-D.ietf-bier-prefix-redistribute]
Zhang, Z., Wu, B., Zhang, Z. J., Wijnands, I., Liu, Y.,
and H. Bidgoli, "BIER Prefix Redistribute", Work in
Progress, Internet-Draft, draft-ietf-bier-prefix-
redistribute-05, 7 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
prefix-redistribute-05>.
[I-D.xzlnp-bier-ioam]
Min, X., Zhang, Z., Liu, Y., Nainar, N. K., and C.
Pignataro, "BIER Encapsulation for IOAM Data", Work in
Progress, Internet-Draft, draft-xzlnp-bier-ioam-06, 31
July 2023, <https://datatracker.ietf.org/doc/html/draft-
xzlnp-bier-ioam-06>.
Zhang, et al. Expires 21 March 2024 [Page 9]
Internet-Draft BIERin6 September 2023
[I-D.zzhang-intarea-generic-delivery-functions]
Zhang, Z. J., Bonica, R., Kompella, K., and G. Mirsky,
"Generic Delivery Functions", Work in Progress, Internet-
Draft, draft-zzhang-intarea-generic-delivery-functions-03,
11 July 2022, <https://datatracker.ietf.org/doc/html/
draft-zzhang-intarea-generic-delivery-functions-03>.
[RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
Weil, "IPv6 Home Networking Architecture Principles",
RFC 7368, DOI 10.17487/RFC7368, October 2014,
<https://www.rfc-editor.org/info/rfc7368>.
Authors' Addresses
Zheng(Sandy) Zhang
ZTE Corporation
Email: zhang.zheng@zte.com.cn
Zhaohui Zhang (editor)
Juniper Networks
Email: zzhang@juniper.net
IJsbrand Wijnands
Individual
Email: ice@braindump.be
Mankamana Mishra
Cisco Systems
Email: mankamis@cisco.com
Hooman Bidgoli
Nokia
Email: hooman.bidgoli@nokia.com
Gyan Mishra
Verizon
Email: gyan.s.mishra@verizon.com
Zhang, et al. Expires 21 March 2024 [Page 10]