Network Working Group X. Xu
Internet-Draft Huawei
Intended status: Standards Track S. Somasundaram
Expires: August 28, 2015 Alcatel-Lucent
C. Jacquenet
France Telecom
R. Raszuk
Mirantis Inc.
February 24, 2015
BIER Encapsulation
draft-xu-bier-encapsulation-02
Abstract
Bit Index Explicit Replication (BIER) is a new multicast forwarding
paradigm which doesn't require an explicit tree-building protocol and
doesn't require intermediate routers to maintain any multicast state.
This document proposes a transport-independent BIER encapsulation
header which is applicable in any kind of transport networks.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 28, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Transport Encapsulation for BIER Header . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Bit Index Explicit Replication (BIER)
[I-D.wijnands-bier-architecture] is a new multicast forwarding
paradigm which doesn't require an explicit tree-building protocol and
doesn't require intermediate routers to maintain any multicast state.
As described in [I-D.wijnands-bier-architecture], BIER requires that
a multicast data packet (e.g., an IP packet or an MPLS packet) to be
encapsulated with a BIER header that carries the information needed
for supporting the BIER forwarding procedures. This information at
least includes Set-Identifier (SI), Multi-Topology Identifier (MT-ID)
and BitString. The SI and the BitString are used together to
identify the set of egress BFRs (BFERs) to which the packet must be
delivered. In addition, to indicate what type of payload is
following the BIER header, a protocol type field is neccessary. This
document proposes a transport-independent BIER encapsulation header
which is applicable in any kind of transport networks.
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].
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2. Terminology
This memo makes use of the terms defined in
[I-D.wijnands-bier-architecture].
3. BIER Header
The BIER header is shown as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | BS Length |Res| SI | MT-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFIR-ID | Sub-domain | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Entropy | DS | TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Ver(sion): a 4-bit field identifying the version of the BIER
header. This document specifies version 0 of the BIER header.
BS Length: a one-octet field indicating the length of the
BitString in 4-byte. Note that legal BS Length values are
specified in [I-D.wijnands-bier-architecture].
Res: a 2-bit reserved field.
SI: a 10-bit field encoding the Set-Identifier (SI) for this
packet.
MT-ID: a one-octet field indicating which routing topology
[RFC4915] [RFC5120] should be applied for BIER forwarding.
BFIR-ID: a 2-octet field encoding the BFR-ID of the BFIR, in the
sub-domain to which the packet has been assigned.
Sub-domain: a one-octet field encoding the sub-domain to which the
packet has been assigned.
Protocol: a one-octet field indicating the protocol type of the
BIER payload as per IP protocol numbers used in the Protocol field
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of the IPv4 header and the Next Header field of IPv6 header. The
valid BIER payload types include but not limited to IPv4, IPv6,
MPLS, VXLAN [RFC7348],VXLAN-GPE [I-D.quinn-vxlan-gpe] , and etc.
The corresponding IP Protocol numbers for VXLAN and VXLAN-GPE are
to be allocated by IANA.
Entropy: a 2-octet field containing an "entropy" value that can be
used for load balancing purposes.
BitString: a variable-length BitString field that, together with
the SI field, identifies all the destination BFERs for this
packet.
DS: The usage of this field is no different from that of the
Differentiated Services (DS) field in the IPv4 or IPv6 headers
[RFC2474].
TTL: The usage of this field is no different from that of the Time
to Live (TTL) field in the IPv4 header.
4. Transport Encapsulation for BIER Header
Since the BIER encapsulation format as specified in Section 3 is
transport-independent, it can be encapsulated with any type of
transport encapsulation headers, such as Ethernet header, PPP header,
IP header, MPLS header, GRE header, UDP header etc. It requires for
each possible transport encapsulation header to be able to indicate
the payload is an BIER header. For instance, In the BIER-in-MAC
encapsulation case, the EtherType field in the Ethernet header is
used. In the BIER-in-IP encapsulation case, the Protocol field in
the IPv4 or or the Next-Header field in the IPv6 header is used. In
the BIER-in-MPLS encapsulation case, either the Protocol Type field
[I-D.xu-mpls-payload-protocol-identifier] within the MPLS packet or a
to-be-assigned Extended Spcial Purpose label [RFC7274] is used.
5. Acknowledgements
TBD.
6. IANA Considerations
This document includes a request to IANA to allocate an EtherType
code,a PPP protocol code, an IPv4 protocol code (i.e., an IPv6 Next-
Header code), a UDP destination port for carring the BIER-
encapsulated packet over the corresponding transport networks.
Furthermore, This document includes a request to IANA to allocate IP
Protocol numbers for VXLAN and VXLAN-GPE respectively.
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7. Security Considerations
TBD.
8. References
8.1. Normative References
[ETYPES] The IEEE Registration Authority, "IEEE 802 Numbers", 2012.
[I-D.wijnands-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-wijnands-bier-architecture-04 (work in
progress), February 2015.
[I-D.xu-mpls-payload-protocol-identifier]
Xu, X. and M. Chen, "MPLS Payload Protocol Identifier",
draft-xu-mpls-payload-protocol-identifier-00 (work in
progress), September 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7274] Kompella, K., Andersson, L., and A. Farrel, "Allocating
and Retiring Special-Purpose MPLS Labels", RFC 7274, June
2014.
8.2. Informative References
[I-D.quinn-vxlan-gpe]
Quinn, P., Agarwal, P., Fernando, R., Lewis, D., Kreeger,
L., Smith, M., Yadav, N., Yong, L., Xu, X., Elzur, U., and
P. Garg, "Generic Protocol Extension for VXLAN", draft-
quinn-vxlan-gpe-03 (work in progress), July 2014.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, December
1998.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC
4915, June 2007.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
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[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, August 2014.
Authors' Addresses
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
S Somasundaram
Alcatel-Lucent
Email: somasundaram.s@alcatel-lucent.com
Christian Jacquenet
France Telecom
Email: christian.jacquenet@orange.com
Robert Raszuk
Mirantis Inc.
Email: robert@raszuk.net
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