Network Working Group X. Xu, Ed.
Internet-Draft Huawei
Intended status: Standards Track S. Somasundaram
Expires: January 1, 2017 Alcatel-Lucent
C. Jacquenet, Ed.
France Telecom
R. Raszuk
Bloomberg LP
June 30, 2016
A Transport-Independent Bit Index Explicit Replication (BIER)
Encapsulation Header
draft-xu-bier-encapsulation-05
Abstract
Bit Index Explicit Replication (BIER) is a new multicast forwarding
paradigm which doesn't require an explicit tree-building protocol nor
intermediate routers to maintain any multicast state. This document
proposes a transport-independent BIER encapsulation header which is
applicable regardless of the underlying transport technology.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF). Note that other groups may also distribute
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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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 1, 2017.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. BIER Header Transport . . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Bit Index Explicit Replication (BIER) [I-D.ietf-bier-architecture] is
a new multicast forwarding paradigm which doesn't require an explicit
tree-building protocol nor intermediate routers to maintain any
multicast state. As described in [I-D.ietf-bier-architecture], BIER
adds a header to a multicast data packet (e.g., an IP packet or an
MPLS packet). The BIER header carries the information needed for
supporting the BIER forwarding procedures. This information at least
includes Subdomain-ID, Set-Identifier (SI) and BitString. Subdomain-
ID, SI and BitString are used together to identify the set of Bit-
Forwarding Egress Routers (BFERs) to which the packet must be
delivered. In addition, a Protocol Type field is neccessary to
indicate what type of payload is following the BIER header. This
document proposes a transport-independent BIER encapsulation header
which is applicable regardless of the underlying transport
technology.
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.ietf-bier-architecture].
3. BIER Header
The BIER header 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | BSL | Reserved | SI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFIR-ID | Sub-domain | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Entropy | DS | TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BIER Header Format.
Ver(sion): a 4-bit field identifying the version of the BIER
header. This document specifies version 0 of the BIER header.
BSL: Bit String Length. If k is the length of the BitString, the
value of this field is log2(k)-5. However, only the following
values are supported [I-D.ietf-bier-mpls-encapsulation] :
* 64 bits
* 128 bits
* 256 bits
* 512 bits
* 1024 bits
* 2048 bits
* 4096 bits
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The value of the BSL field MUST NOT be set to any value other than
those listed above. A received packet containing another value in
this field SHOULD be discarded, and an error logged.
SI: a 10-bit field encoding the Set-Identifier (SI) for this
packet.
BFIR-ID: a 2-octet field encoding the BFR-ID of the Bit-Forwarding
Ingress Router (BFIR), in the BIER sub-domain where the packet is
forwarded to.
Sub-domain: a one-octet field encoding the sub-domain where the
packet is forwarded to.
Protocol: a one-octet field indicating the protocol type of the
BIER payload as per the protocol numbers used in the Protocol
field [RFC5237]of the IPv4 header and the Next Header field of an
IPv6 header. The valid BIER payload types include (but are not
limited to) IPv4, IPv6, MPLS, VXLAN [RFC7348],VXLAN-GPE
[I-D.ietf-nvo3-vxlan-gpe]. 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 of IPv4 and 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. BIER Header Transport
Since the BIER header format as specified in Section 3 is transport-
independent by design, it can be carried with any type of transport
encapsulation headers, such as an Ethernet header, a PPP header, an
IP header, an MPLS header, a GRE header, an UDP header etc. Any
possible transport encapsulation header must be able to indicate the
payload is an BIER header. For instance, in the BIER-in-MAC
encapsulation case, the EtherType [ETYPES] field of the Ethernet
header is used for that purpose. In the BIER-in-IP encapsulation
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case, the Protocol field of the IPv4 header or or the Next-Header
field of the IPv6 header are 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
yet-to-be-assigned Extended Special Purpose label [RFC7274] can be
used.
5. Acknowledgements
Thanks Antoni Przygienda and IJsbrand Wijnands for their valuable
comments and suggestions on this document.
6. IANA Considerations
This document includes a request to IANA to allocate an EtherType
code,a PPP protocol code, an IPv4 protocol code, an IPv6 Next-Header
code, a UDP destination port to indicate that BIER-encapsulated data
follows. Furthermore, this document includes a request to IANA to
allocate IP Protocol numbers for VXLAN and VXLAN-GPE respectively.
7. Security Considerations
As mentioned in [I-D.ietf-bier-architecture], when BIER is paired
with any transport underlay, it inherits the security considerations
of the corresponding transport layer. Also, SI and BFIR-ID fields of
the BIER header may carry values other than those intended by the
BFIR at the risk of misdelivering the packet. Means to protect BFR
routers against Man-in-the-Middle and Denial of Service attacks must
be provided.
8. References
8.1. Normative References
[ETYPES] The IEEE Registration Authority, "IEEE 802 Numbers", 2012.
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-03 (work in
progress), January 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
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8.2. Informative References
[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and
S. Aldrin, "Encapsulation for Bit Index Explicit
Replication in MPLS Networks", draft-ietf-bier-mpls-
encapsulation-04 (work in progress), April 2016.
[I-D.ietf-nvo3-vxlan-gpe]
Kreeger, L. and U. Elzur, "Generic Protocol Extension for
VXLAN", draft-ietf-nvo3-vxlan-gpe-02 (work in progress),
April 2016.
[I-D.xu-mpls-payload-protocol-identifier]
Xu, X., "MPLS Payload Protocol Identifier", draft-xu-mpls-
payload-protocol-identifier-01 (work in progress), June
2016.
[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,
DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>.
[RFC5237] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
the Protocol Field", BCP 37, RFC 5237,
DOI 10.17487/RFC5237, February 2008,
<http://www.rfc-editor.org/info/rfc5237>.
[RFC7274] Kompella, K., Andersson, L., and A. Farrel, "Allocating
and Retiring Special-Purpose MPLS Labels", RFC 7274,
DOI 10.17487/RFC7274, June 2014,
<http://www.rfc-editor.org/info/rfc7274>.
[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, DOI 10.17487/RFC7348, August 2014,
<http://www.rfc-editor.org/info/rfc7348>.
Authors' Addresses
Xiaohu Xu (editor)
Huawei
Email: xuxiaohu@huawei.com
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S Somasundaram
Alcatel-Lucent
Email: somasundaram.s@alcatel-lucent.com
Christian Jacquenet (editor)
France Telecom
Email: christian.jacquenet@orange.com
Robert Raszuk
Bloomberg LP
Email: robert@raszuk.net
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