BIER Z. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track Z. Zhang, Ed.
Expires: August 26, 2021 Juniper Networks
I. Wijnands
Individual
M. Mishra
Cisco Systems
H. Bidgoli
Nokia
G. Mishra, Ed.
Verizon
February 22, 2021
Supporting BIER in IPv6 Networks (BIERin6)
draft-zhang-bier-bierin6-09
Abstract
BIER is a new architecture for the forwarding of multicast data
packets without requiring per-flow state inside the network. This
document describes how the existing BIER encapsulation specified in
RFC 8296 works in an IPv6 non-MPLS network, 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/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 August 26, 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified 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 3
2. IPv6 Header . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. IPv6 Options Considerations . . . . . . . . . . . . . . . 5
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6 Encapsulation Advertisement . . . . . . . . . . . . . . 6
4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Inter-area prefix redistribution . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
BIER [RFC8279] is a new architecture for the forwarding of multicast
data packets. It provides optimal forwarding through a "multicast
domain" and it does not precondition construction of a multicast
distribution tree, nor does it require intermediate nodes to maintain
any per-flow state.
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This document specifies non-MPLS BIER forwarding in an IPv6 [RFC8200]
environment, referred to as BIERin6, using non-MPLS BIER
encapsulation specified in [RFC8296].
MPLS BIER forwarding in IPv6 is outside the scope of this document.
This document uses terminology defined in [RFC8279] and [RFC8296].
1.1. BIER over L2/Tunnels
[RFC8296] defines the BIER encapsulation format in MPLS and non-MPLS
environment. In case of non-MPLS environment, a BIER packet is the
payload of an "outer" encapsulation, which has a "next header"
codepoint that is set to a value that means "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 "non-MPLS 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:
o An operator mandates all traffic to be carried in IPv6.
o A BFR does not have BIER support in its "fast forwarding path" and
relies on "slow/software forwarding path", e.g. in environments
like [RFC7368] where high throughput multicast forwarding
performance is not critical.
1.2. Considerations of Requirements for BIER in IPv6 Networks
[draft-ietf-bier-ipv6-requirements] lists mandatory and optional
requirements for BIER in IPv6 Networks. As a solution based on the
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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:
o 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.
o Generic Fragmentation/ESP
[I-D.zzhang-tsvwg-generic-transport-functions]: a BFIR does
generic fragmentation and/or ESP (without using IPv6
encapsulation) and the resulting packets are treated as BIER
payload.
Either way, the fragmentation/ESP is handled by a layer outside of
BIER and then the resulting packets are treated as BIER payload.
BIERin6 does support SRv6 based overlay services (e.g. MVPN/EVPN).
One of the following methods can be used (relevant overlay signaling
will be specified separately):
o An ingress PE (which is a BFIR) can encapsulate customer packets
with an IPv6 header (with optional fragmentation and ESP extension
headers). The destination address is a multicast locator plus the
Fucn/Arg portion that identifies the service. That IPv6 packet is
then treated as BIER payload. An egress PE (which is a BFER) uses
the standard SRv6 procedures to forward the IPv6 packet that is
exposed after the BIER header is decapsulated.
o Alternatively, since only the destination IPv6 address in the
above-mentioned 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 IPv6 address (instead of an entire
IPv6 header) is added between the BIER header and original
payload.
BIERin6 being a solution based on [RFC8279] [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 (instead of using local 5-tuple input key to a
hash function to locally generate the stateless 20-bit flow label) so
that routers along the tunnel can do ECMP based on Flow Labels. 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 function, otherwise it
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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:
o BIER OAM specified in [I-D.ietf-bier-ping]
o BIER BFD specified in [I-D.ietf-bier-bfd]
o BIER Performance Measurement specified in [I-D.ietf-bier-pmmm-oam]
o BIER Path Maximum Transmission Unit Discovery specified in
[I-D.ietf-bier-path-mtu-discovery]
o BIER IOAM specified in [I-D.xzlnp-bier-ioam]
2. IPv6 Header
Whenever IPv6 encapsulation is used for BIER forwarding, 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
IPv6 TTL MUST be set to 1. Otherwise, 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.
2.1. IPv6 Options Considerations
For directly connected BIER routers, IPv6 Hop-by-Hop or Destination
options are irrelevant and SHOULD NOT be inserted by BFIR on the
BIERin6 packet. In this case IPv6 header, Next Header field should
be set to TBD. Any IPv6 packet arriving on BFRs and BFERs, with
multiple extension header where the last extension header has a Next
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Header field set to TBD, SHOULD be discard and the node should
transmit an ICMP Parameter Problem message to the source of the
packet (BFIR) with an ICMP code value of TBD10 ('invalid options for
BIERin6').
This also indicates that for disjoint BIER routers using IPv6
encapsulation, there SHOULD NOT be any IPv6 Hop-by-Hop or Destination
options be present in a BIERin6 packet. In this case, if additional
traffic engineering is required, IPv6 tunneling (i.e. BIERin6 over
SRv6) can be implemented.
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-ethernet-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-ethernet-extensions] is needed.
Otherwise, a node that requires IPv6 encapsulation MUST advertise the
BIER IPv6 transportation 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.
In presence of multiple encapsulation possibilities hop-by-hop it is
a matter of local policy which encapsulation is imposed and the
receiving router MUST accept all encapsulations that it advertised.
4.1. Format
The BIER IPv6 transportation is a new sub-sub-TLV of BIER Ethernet
Encapsulation sub-TLV defined in OSPFv3, and a new sub-sub-sub-TLV of
BIER Ethernet Encapsulation sub-sub-TLV defined in ISIS, as per
[I-D.ietf-bier-lsr-ethernet-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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o Type: For OSPF, value TBD1 (prefer 1) is used to indicate it is
the IPv6 transportation sub-TLV. For ISIS, value TBD2 (prefer 1)
is used to indicate it is the IPv6 transportation sub-sub-TLV.
o Length: 0.
4.2. Inter-area prefix redistribution
When BFR-prefixes are advertised across IGP areas per
[I-D.ietf-bier-lsr-ethernet-extensions] or redistributed across
protocol boundaries per [I-D.ietf-bier-prefix-redistribute], the BIER
IPv6 transportation sub-sub-TLV or sub-sub-sub-TLV MAY be re-
advertised/re-distributed as well.
5. IANA Considerations
IANA is requested to assign a new "BIER" type for "Next Header" in
the "Assigned Internet Protocol Numbers" registry.
IANA is requested to assign a new "BIERin6" type for "invalid
options" in the "ICMP code value" registry.
IANA is requested to assign a new "IPv6 address" type in the "BIER
Next Protocol Identifiers" registry.
IANA is requested to assign a new "BIER IPv6 transportation Sub-sub-
TLV" type in the "OSPFv3 BIER Ethernet Encapsulation sub-TLV"
Registry.
IANA is requested to set up a new "BIER IPv6 transportation Sub-sub-
sub-TLV" type in the "IS-IS BIER Ethernet Encapsulation sub-sub-TLV"
Registry.
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
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8.1. 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>.
[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>.
[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>.
[RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z.
Zhang, "Bit Index Explicit Replication (BIER) Support via
IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018,
<https://www.rfc-editor.org/info/rfc8401>.
8.2. Informative References
[I-D.ietf-bier-bar-ipa]
Zhang, Z., Przygienda, T., Dolganow, A., Bidgoli, H.,
Wijnands, I., and A. Gulko, "BIER Underlay Path
Calculation Algorithm and Constraints", draft-ietf-bier-
bar-ipa-07 (work in progress), September 2020.
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[I-D.ietf-bier-bfd]
Xiong, Q., Mirsky, G., hu, f., and C. Liu, "BIER BFD",
draft-ietf-bier-bfd-00 (work in progress), November 2020.
[I-D.ietf-bier-idr-extensions]
Xu, X., Chen, M., Patel, K., Wijnands, I., and T.
Przygienda, "BGP Extensions for BIER", draft-ietf-bier-
idr-extensions-07 (work in progress), September 2019.
[I-D.ietf-bier-ipv6-requirements]
McBride, M., Xie, J., Geng, X., Dhanaraj, S., Asati, R.,
Zhu, Y., Mishra, G., and Z. Zhang, "BIER IPv6
Requirements", draft-ietf-bier-ipv6-requirements-09 (work
in progress), September 2020.
[I-D.ietf-bier-lsr-ethernet-extensions]
Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang,
Z., and J. Xie, "LSR Extensions for BIER over Ethernet",
draft-ietf-bier-lsr-ethernet-extensions-02 (work in
progress), December 2020.
[I-D.ietf-bier-non-mpls-bift-encoding]
Wijnands, I., Mishra, M., Xu, X., and H. Bidgoli, "An
Optional Encoding of the BIFT-id Field in the non-MPLS
BIER Encapsulation", draft-ietf-bier-non-mpls-bift-
encoding-03 (work in progress), November 2020.
[I-D.ietf-bier-ospfv3-extensions]
Psenak, P., Nainar, N., and I. Wijnands, "OSPFv3
Extensions for BIER", draft-ietf-bier-ospfv3-extensions-03
(work in progress), November 2020.
[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", draft-ietf-bier-path-mtu-
discovery-09 (work in progress), November 2020.
[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-09 (work in progress), December 2020.
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[I-D.ietf-bier-prefix-redistribute]
Zhang, Z., Bo, W., Zhang, Z., Wijnands, I., and Y. Liu,
"BIER Prefix Redistribute", draft-ietf-bier-prefix-
redistribute-00 (work in progress), August 2020.
[I-D.xzlnp-bier-ioam]
Min, X., Zhang, Z., Liu, Y., Nainar, N., and C. Pignataro,
"Bit Index Explicit Replication (BIER) Encapsulation for
In-situ OAM (IOAM) Data", draft-xzlnp-bier-ioam-01 (work
in progress), January 2021.
[I-D.zhang-bier-babel-extensions]
Zhang, Z. and T. Przygienda, "BIER in BABEL", draft-zhang-
bier-babel-extensions-04 (work in progress), November
2020.
[I-D.zzhang-tsvwg-generic-transport-functions]
Zhang, Z., Bonica, R., and K. Kompella, "Generic Transport
Functions", draft-zzhang-tsvwg-generic-transport-
functions-00 (work in progress), November 2020.
[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
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Mankamana Mishra
Cisco Systems
EMail: mankamis@cisco.com
Hooman Bidgoli
Nokia
EMail: hooman.bidgoli@nokia.com
Gyan Mishra (editor)
Verizon
EMail: gyan.s.mishra@verizon.com
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