BIER Z. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track A. Przygienda
Expires: January 9, 2020 Juniper Networks, Inc.
I. Wijnands
Cisco Systems
H. Bidgoli
Nokia
M. McBride
Futurewei
July 8, 2019
BIER in IPv6 (BIERin6)
draft-zhang-bier-bierin6-03
Abstract
BIER is a new architecture for the forwarding of multicast data
packets. This document defines native IPv6 encapsulation for BIER
hop-by-hop forwarding or BIERin6 for short.
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 RFC2119.
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
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 January 9, 2020.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPv6 Header . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. IPv6 Options Considerations . . . . . . . . . . . . . . . 3
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. IPv6 Encapsulation Advertisement . . . . . . . . . . . . . . 4
4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Inter-area prefix redistribution . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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 necessarily precondition construction of a
multicast distribution tree, nor does it require intermediate nodes
to maintain any per-flow state.
This document specifies non-MPLS BIER forwarding in an IPv6 [RFC8200]
environment, refferred 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].
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[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 protocol"
codepoint that is set to a value that means "non-MPLS BIER".
That can be used as is in a pure IPv6 non-mpls environment. Between
two directly connected BFRs, a BIER header could directly follow link
layer header, e.g., an Ethernet header (with the Ethertype set to
0xAB37). If a BFR needs to tunnel BIER packets to another BFR, e.g.
per [RFC8279] Section 6.9, 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".
The IPv6 encapsulation could be used even between two directly
connected BFRs 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.
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-ID in the IPv6 packet SHOULD be copied from the entropy
field in the BIER encapsulation.
2.1. IPv6 Options Considerations
RFC 8200 section 4, defines the IPv6 extension headers. Currently
there are two defined extension headers, Hop-by-Hop and Destination
options header, which can carry a variable number of options. These
extension headers are inserted by the source node.
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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
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
specificed in [I-D.dhanaraj-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.dhanaraj-bier-lsr-ethernet-extensions] is needed.
Otherwise, a node that requires IPv6 encapsualtion MUST advertise the
BIER IPv6 transportation 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-TLV of BIER defined in OSPF
[RFC8444], and a new sub-sub-TLV of BIER Info sub-TLV defined in ISIS
[RFC8401].
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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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: For OSPF, value TBD1 (prefer 12) is used to indicate it is
the IPv6 transportation sub-TLV. For ISIS, value TBD2 (prefer 3)
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.dhanaraj-bier-lsr-ethernet-extensions] or redistributed across
protocol boundaries per [I-D.zwzw-bier-prefix-redistribute], the BIER
IPv6 transportation sub-TLV or 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 "BIER IPv6 transportation Sub-TLV"
type in the "OSPFv2 Extended Prefix TLV Sub-TLVs" Registry.
IANA is requested to set up a new "BIER IPv6 transportation Sub-sub-
TLV" type in the "IS-IS BIER Info sub-TLV" Registry.
6. Security Considerations
General IPv6 and BIER security considerations apply.
7. Acknowledgement
The authors would like to thank Jeffrey Zhang for his review and
valuable contributions.
8. References
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8.1. Normative References
[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>.
[RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A.,
Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2
Extensions for Bit Index Explicit Replication (BIER)",
RFC 8444, DOI 10.17487/RFC8444, November 2018,
<https://www.rfc-editor.org/info/rfc8444>.
8.2. Informative References
[I-D.dhanaraj-bier-lsr-ethernet-extensions]
Dhanaraj, S., Wijnands, I., Psenak, P., Zhang, Z., Yan,
G., and J. Xie, "LSR Extensions for BIER over Ethernet",
draft-dhanaraj-bier-lsr-ethernet-extensions-00 (work in
progress), January 2019.
[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-04 (work in progress), May 2019.
[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-06 (work in progress), January 2019.
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[I-D.ietf-bier-non-mpls-bift-encoding]
Wijnands, I., 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-01
(work in progress), October 2018.
[I-D.zhang-bier-babel-extensions]
Zhang, Z. and T. Przygienda, "BIER in BABEL", draft-zhang-
bier-babel-extensions-01 (work in progress), June 2017.
[I-D.zwzw-bier-prefix-redistribute]
Zhang, Z., Bo, W., Zhang, Z., and I. Wijnands, "BIER
Prefix Redistribute", draft-zwzw-bier-prefix-
redistribute-02 (work in progress), March 2019.
[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: zzhang_ietf@hotmail.com
Tony Przygienda
Juniper Networks, Inc.
EMail: prz@juniper.net
IJsbrand Wijnands
Cisco Systems
EMail: ice@cisco.com
Hooman Bidgoli
Nokia
EMail: hooman.bidgoli@nokia.com
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Mike McBride
Futurewei
EMail: mmcbride@futurewei.com
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