BIER Working Group W. Wang
Internet-Draft A. Wang
Intended status: Standards Track China Telecom
Expires: September 22, 2022 H. Chen
Futurewei
G. Mishra
Verizon Inc.
B. Xu
Huawei Technologies (2012Lab)
March 21, 2022
Routing Header Based BIER Information Encapsulation
draft-wang-bier-rh-bier-05
Abstract
This draft proposes one new encapsulation schema of Bit Index
Explicit Replication (BIER) information to transfer the multicast
packets within the IPv6 network. By using a new type of IPv6 Routing
Header to forward the packet, the original source address and
destination address of the multicast packet is kept unchanged along
the forwarding path. Such encapsulation schema can make full use of
the existing IPv6 quality assurance solutions to provide high-quality
multicast service.
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 September 22, 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
Wang, et al. Expires September 22, 2022 [Page 1]
Internet-Draft RH-BIER March 2022
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 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. BIER Routing Header . . . . . . . . . . . . . . . . . . . . . 3
4. Multicast Packet Forwarding Procedures . . . . . . . . . . . 4
4.1. All nodes in BIER domain support BIER Routing Header . . 5
4.2. Some nodes in BIER domain do not support BIER Routing
Header . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Bit Index Explicit Replication (BIER) is a new multicast technology
based on IPv6 defined in [RFC8279]. In BIER domain, the set of
destination nodes of multicast message is mapped into a BitString and
encapsulated into the BIER header. The position of each bit in the
BitString represents an BFER. Compared with the traditional
multicast technologies, the nodes in BIER domain do not need to
maintain a multicast tree and keep the multicast flow state for each
multicast flow.
Currently, there are two methods for encapsulating BIER information
based on IPv6 in IETF: BIERin6([I-D.ietf-bier-bierin6]) and
BIERv6([I-D.xie-bier-ipv6-encapsulation]).
BIERin6 carries BIER information by defining a new IPv6 next header
type. During the forwarding process, the source address and
destination address in the header will be changed.
BIERv6 carries bier related information by defining an new type of
destination options header (i.e. bier option). The source address in
Wang, et al. Expires September 22, 2022 [Page 2]
Internet-Draft RH-BIER March 2022
the header remains unchanged but the destination address will be
changed along the forwarding path.
The differences between the above two BIER encapsulation and
forwarding schemes are unfavorable for the development of BIER and
its derivatives. In addition, when there is error in the forward
process of the multicast packet, the change of source address and
destination address during transmission will increase the difficulty
of fault location and traceability.
This draft proposes a BIER information transmission scheme without
changing the multicast source and destination addresses in the outer
IPv6 header. The relevant BIER information is encapsulated within
the newly defined IPv6 Routing Header type, each intermediate BIER
router will route the multicast packet based on the BitString
information and its associated BIFT. The multicast source and
destination address are not changed along the forwarding path.
The characteristics of such schema are helpful to the rapid fault
location and traceability, and can make full use of the existing IPv6
quality assurance technologies to provide high-quality multicast
service.
2. Conventions used in this document
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] .
3. BIER Routing Header
One new type of IPv6 Routing Header is defined according to
[RFC8200]. The message format is shown in Figure 1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | BIER-TE Algo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BIER-TE Algorithm specified part |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The format of BIER Routing Header
Where:
o Next Header (8 bits): indicating the message header type
immediately after the Routing Header.
Wang, et al. Expires September 22, 2022 [Page 3]
Internet-Draft RH-BIER March 2022
o HDR Ext Len (8 bits): indicating the length of the Routing Header.
o Routing Type (8 bits): TBD. Identifying the newly defined Routing
Header to encode BIER information.
o BIER-TE Algo (8 bits): indicating the BIER-TE Algorithm for RH-
BIER packets. Different values of this field refer to different
BIER-TE Algorithm:
* Value 0: reserved.
* Value 1: IGP
* Value 2: CGM2 (see [I-D.eckert-bier-cgm2-rbs])
* Value 3: MRH (see [I-D.chen-pim-mrh6])
* Value 4-127: Expert Reviews
* Value 128-255: Flexible Algorithms
o BIER-TE Algorithm specified part (variable): the encoding of this
part depends on the value of BIER-TE Algo field:
* Value 1: The BIER-TE Algorithm is IGP, the encoding format of
this part is described in [RFC8296].
* Value 2: The BIER-TE Algorithm is CGM2, the encoding format of
this part is described in [I-D.eckert-bier-cgm2-rbs].
* Value 3: The BIER-TE Algorithm is MRH6, the encoding format of
this part is described in [I-D.chen-pim-mrh6].
4. Multicast Packet Forwarding Procedures
Based on the newly defined BIER Routing Header, the nodes support
BIER Routing Header will perform the following steps to forward the
multicast packets:
1) When a BFIR receive a multicast packet, it will find out the
destination address and RD that relate to the source interface of the
packet. BFIR looks up its End.MVPN mapping table to find the
associated End.MVPN, and encapsulate a IPv6 Header with BIER Routing
Header. The payload is user data, the source address is the IPv6
address of BFIR, and destination address is End.MVPN. BitString in
BIER Routing Header indicates the BFERs that want to receives such
multicast packet.
Wang, et al. Expires September 22, 2022 [Page 4]
Internet-Draft RH-BIER March 2022
2) BFIR checks whether there is BIFT corresponding to the BIFT-id
locally. If not, it will discard the packet; otherwise, it will
check whether the direct-connected node support BIER Routing Header.
If the direct-connected node supports BIER Routing Header, proceeding
to step 3). If the direct-connected node doesn't support BIER
Routing Header, proceeding to step 2.1) .
2.1) BFIR Calculates the IPv6 address of next hop that support BIER
Routing Header.
2.2) Encapsulating an outer IPv6 Header to the multicast packet. The
calculated IPv6 address is used as the destination address of the
outer IPv6 Header, and its own IPv6 address is used as the source
address of the outer IPv6 Header. BitString will not be changed.
2.3) Sending the encapsulated packet to the direct-connected node,
the node will perform normal IPv6 forwarding according to the outer
IPv6 Header.
3) Performing the normal BIER forwarding process as described in
[RFC8279].
For a BFR, it performs as described in Section 4.2.
The detail procedures for forwarding the multicast packets based on
the newly defined Routing Header are described in the following
sections.
4.1. All nodes in BIER domain support BIER Routing Header
+---+
+-----------+ B +----------+
| +---+ |
| 0:01000000 |
| |
| |
| |
+-+-+ +-+-+ (Packet 2) +---+ (Packet 3)+---+
| A |0:10000000 0:00100000| C +------------+ E +-----------+ F |
+-+-+ +-+-+ +---+ +---+
| | 0:00001000 0:00000100
| |
| |
| |
| 0:00010000 |
| +---+ |
+-----------+ D +----------+
(Packet 1) +---+
Wang, et al. Expires September 22, 2022 [Page 5]
Internet-Draft RH-BIER March 2022
Packet 1
+------------------------------------+
IPv6 | IPv6 Address of A |
Header +------------------------------------+
with | IPv6 Multicast Destination Address |
BIER +------------------------------------+
Routing| BIER RH(BitString = 00101100) |
Header +------------------------------------+
| Original multicast packet |
+------------------------------------+
Packet 2
+------------------------------------+
IPv6 | IPv6 Address of A |
Header +------------------------------------+
with | IPv6 Multicast Destination Address |
BIER +------------------------------------+
Routing| BIER RH(BitString = 00001100) |
Header +------------------------------------+
| Original multicast packet |
+------------------------------------+
Packet 3
+------------------------------------+
IPv6 | IPv6 Address of A |
Header +------------------------------------+
with | IPv6 Multicast Destination Address |
BIER +------------------------------------+
Routing| BIER RH(BitString = 00000100) |
Header +------------------------------------+
| Original multicast packet |
+------------------------------------+
Figure 2: All nodes in BIER domain support BIER Routing Header
The topology is shown in Figure 2, node A-F support BIER Routing
Header. The packet need to be transmitted from A to F. The changes
of the Routing Header have been given in Figure 2.
1). Node A is BFIR, when it receives a multicast packet, it will
encapsulate a IPv6 Header with BIER Routing Header to the packet.
2). Node A checks whether there is BIFT corresponding to the BIFT-id
locally. If not, discarding the packet; otherwise, forwarding the
packet according to the BIFT related to the BIFT-id.
3). Node D-E repeat the step 2).
Wang, et al. Expires September 22, 2022 [Page 6]
Internet-Draft RH-BIER March 2022
4). Node F looks up the associated table and submits the packet to
the new multicast downstreams.
During the forwarding procedures, the source & destination address in
IPv6 header are not changed, only the BitString in BIER Routing
Header is updated.
4.2. Some nodes in BIER domain do not support BIER Routing Header
+---+
+-----------+ B +-----------+
| +---+ |
| 0:01000000 |
| |
| |
| |
+-+-+ +-+-+ +---+ (Packet 3) +---+
| A |0:10000000 | C +------------+ E +------------+ F |
+-+-+ +-+-+ +---+ +---+
| | 0:00001000 0:00000100
| |
| |
| |
| 0:00010000 |
| +---+ |
+-----------+ D +-----------+
(Packet 1) +---+ (Packet 2)
Packet 1
+------------------------------------+
IPv6 | IPv6 Address of A |
Header +------------------------------------+
with | IPv6 Multicast Destination Address |
BIER +------------------------------------+
Routing| BIER RH(BitString = 00001100) |
Header +------------------------------------+
| Original multicast packet |
+------------------------------------+
Packet 2
+------------------------------------+
Outer | Source IP Address = D |
IPv6 +------------------------------------+
Header | Destination IP Address = E |
+------------------------------------+
Inner | IPv6 Address of A |
IPv6 +------------------------------------+
Wang, et al. Expires September 22, 2022 [Page 7]
Internet-Draft RH-BIER March 2022
Header | IPv6 Multicast Destination Address |
with +------------------------------------+
BIER | BIER RH(BitString = 00001100) |
Routing+------------------------------------+
Header | Original multicast packet |
+------------------------------------+
Packet 3
+-------------------------------------+
IPv6 | IPv6 Address of A |
Header +-------------------------------------+
with | IPv6 Multicast Destination Address |
BIER +-------------------------------------+
Routing| BIER RH(BitString = 00000100) |
Header +-------------------------------------+
| Original multicast packet |
+-------------------------------------+
Figure 3: Some nodes in BIER domain do not support BIER Routing Header
The topology is shown in Figure 3, all nodes expect node C support
BIER Routing Header. The packet need to be transmitted from A to F.
The change of the Header has been given in the Figure 3.
1). After receiving a multicast packet, node A encapsulates a IPv6
Header with BIER Routing Header to it, and forwards the packet to
node D according to the BIFT.
2). Node D calculates the IPv6 address of next hop node(Node E) that
supports BIER Routing Header, and encapsulates an outer IPv6 Header
to the packet. The source IPv6 address is the IPv6 address of
itself, and the destination IPv6 address is the IPv6 address of node
E. Then, sending the packet to node C.
3). Node C performs normal IPv6 forwarding according to the outer
IPv6 header and sends the packet to node E.
4). Node E decapsulates the outer IPv6 header and forwards the
packet according to the BIFT to node F.
5). Node F looks up the associated table and submits the packet to
the new multicast downstreams.
In the forwarding procedures, the source address and destination
address in the Inner IPv6 Header are not changed, only the BitString
in BIER Routing Header is updated.
Wang, et al. Expires September 22, 2022 [Page 8]
Internet-Draft RH-BIER March 2022
5. Security Considerations
TBD
6. IANA Considerations
This document defines a new type of IPv6 Routing Header - BIER
Routing Header. The code point is from the "Internet Protocol
Version 6 (IPv6) Parameters - Routing Types". It is recommended to
set the code point of BIER Routing Header to 7.
7. References
7.1. 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>.
[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>.
7.2. Informative References
[I-D.chen-pim-mrh6]
Chen, H., McBride, M., Fan, Y., Li, Z., Geng, X., Toy, M.,
Mishra, G. S., Liu, Y., Wang, A., Liu, L., and X. Liu,
"Multicast using Multicast Routing Header", draft-chen-
pim-mrh6-01 (work in progress), March 2022.
Wang, et al. Expires September 22, 2022 [Page 9]
Internet-Draft RH-BIER March 2022
[I-D.eckert-bier-cgm2-rbs]
Eckert, T. and B. (. Xu, "Carrier Grade Minimalist
Multicast (CGM2) using Bit Index Explicit Replication
(BIER) with Recursive BitString Structure (RBS)
Addresses", draft-eckert-bier-cgm2-rbs-01 (work in
progress), February 2022.
[I-D.ietf-bier-bierin6]
Zhang, Z., Zhang, Z., Wijnands, I., Mishra, M., Bidgoli,
H., and G. Mishra, "Supporting BIER in IPv6 Networks
(BIERin6)", draft-ietf-bier-bierin6-04 (work in progress),
March 2022.
[I-D.xie-bier-ipv6-encapsulation]
Xie, J., Geng, L., McBride, M., Asati, R., Dhanaraj, S.,
Zhu, Y., Qin, Z., Shin, M., Mishra, G., and X. Geng,
"Encapsulation for BIER in Non-MPLS IPv6 Networks", draft-
xie-bier-ipv6-encapsulation-10 (work in progress),
February 2021.
Authors' Addresses
Wei Wang
China Telecom
Beiqijia Town, Changping District
Beijing, Beijing 102209
China
Email: weiwang94@foxmail.com
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing, Beijing 102209
China
Email: wangaj3@chinatelecom.cn
Huaimo Chen
Futurewei
Beiqijia Town, Changping District
Boston, MA
USA
Email: Huaimo.chen@futurewei.com
Wang, et al. Expires September 22, 2022 [Page 10]
Internet-Draft RH-BIER March 2022
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring MD 20904
United States of America
Phone: 301 502-1347
Email: gyan.s.mishra@verizon.com
Bing (Robin) Xu
Huawei Technologies (2012Lab)
Huawei Building, No.156 Beiqing Rd.
Beijing, Beijing 100095
China
Email: bing.xu@huawei.com
Wang, et al. Expires September 22, 2022 [Page 11]