Internet DRAFT - draft-xu-bier-encapsulation
draft-xu-bier-encapsulation
Network Working Group X. Xu, Ed.
Internet-Draft Huawei
Intended status: Standards Track S. Somasundaram
Expires: March 27, 2017 Alcatel-Lucent
C. Jacquenet, Ed.
France Telecom
R. Raszuk
Bloomberg LP
Z. Zhang, Ed.
Juniper
September 23, 2016
A Transport-Independent Bit Index Explicit Replication (BIER)
Encapsulation Header
draft-xu-bier-encapsulation-06
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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 27, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. BIER Header Transport . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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 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].
2. Terminology
This memo makes use of the terms defined in
[I-D.ietf-bier-architecture].
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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 | Resv | Entropy |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFIR-ID | DS | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SI | Sub-domain |O| Resv| 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.
Entropy: a 20-bit field containing an "entropy" value that can be
used for load balancing purposes.
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.
DS: The usage of this field is no different from that of the
Differentiated Services (DS) field of IPv4 and IPv6 headers.
[RFC2474].
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. Theoretically, with the use of the IPv4/IPv6
equivalent Protocol/Next-Header field, the payload of a BIER
packet could be any type of payload permitted within the IPv4/IPv6
packet. However, this document currently only considers the use
of the BIER encapsulation for "transport" type services where the
encapsulated packets are either L2.5 (e.g., MPLS) or L3 (e.g., IP)
packets . The valid BIER payload types include (but are not
limited to) IPv4, IPv6, MPLS, VXLAN [RFC7348],VXLAN-GPE
[I-D.ietf-nvo3-vxlan-gpe] and LISP [RFC6830]. The corresponding
IP Protocol numbers for VXLAN, VXLAN-GPE and LISP are to be
allocated by IANA.
SI: a 10-bit field encoding the Set-Identifier (SI) for this
packet in the case where the O-Flag bit is cleared.
Sub-domain: a 10-bit field encoding the sub-domain where the
packet is forwarded to in the case where the O-Flag bit is
cleared.
O-flag: If it's set, the leftmost 20 bits (i.e., the combination
of the SI and Sub-domain fields) should be interpreted as an
opaque number signaled and used much as the MPLS-BIER label in
MPLS BIER encapsulation [I-D.ietf-bier-mpls-encapsulation]. A BFR
signals the mapping between the opaque number and (subdomain-id,
set-id, BSL) and it derives the (subdomain-id,set-id,BSL) from the
opqaue number in an incoming BIER header just like in the MPLS
BIER encapsulation case, except that regular MPLS signaling and
forwarding infrastructure is not required.
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TTL: The usage of this field is no different from that of the Time
To Live (TTL) field in the IPv4 header.
BitString: a variable-length BitString field that, together with
the SI and Sub-domain fields, identifies all the destination BFERs
for this packet.
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
case, the Protocol field of the IPv4 header or the Next-Header field
of the IPv6 header are used. In the MPLS transport case, the MPLS-
BIER encapsulation [I-D.ietf-bier-mpls-encapsulation] SHOULD be used
instead. Note that more details about BIER-in-UDP encapsualtion
(e.g., UDP checksum and congestion control) will be specified in
future versions of this document.
5. Acknowledgements
Thanks Antoni Przygienda, IJsbrand Wijnands, Eric Rosen and Toerless
Eckert 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, VXLAN-GPE and LISP
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.
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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-04 (work in
progress), July 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>.
8.2. Informative References
[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J.,
Aldrin, S., and I. Meilik, "Encapsulation for Bit Index
Explicit Replication in MPLS Networks", draft-ietf-bier-
mpls-encapsulation-05 (work in progress), July 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.
[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>.
[RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830,
DOI 10.17487/RFC6830, January 2013,
<http://www.rfc-editor.org/info/rfc6830>.
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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, DOI 10.17487/RFC7348, August 2014,
<http://www.rfc-editor.org/info/rfc7348>.
Authors' Addresses
Xiaohu Xu (editor)
Huawei
Email: xuxiaohu@huawei.com
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
Zhaohui Zhang (editor)
Juniper
Email: zzhang@juniper.net
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