Internet DRAFT - draft-dhanaraj-bier-lsr-ethernet-extensions
draft-dhanaraj-bier-lsr-ethernet-extensions
Internet Engineering Task Force S. Dhanaraj, Ed.
Internet-Draft Huawei
Updates: 8296 (if approved) IJ. Wijnands
Intended status: Standards Track P. Psenak
Expires: August 2, 2019 Cisco Systems, Inc.
Z. Zhang
Juniper Networks.
G. Yan
J. Xie
Huawei
January 29, 2019
LSR Extensions for BIER over Ethernet
draft-dhanaraj-bier-lsr-ethernet-extensions-00
Abstract
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain multicast related per-flow
state. BIER can be supported in MPLS and non-MPLS networks. The
common BIER header format and encapsulation for MPLS and non-MPLS
networks is specified in [RFC8296].
This document specifies the required extensions to the IS-IS
[RFC1195] and OSPFv2 [RFC2328] protocol for supporting BIER in non-
MPLS networks using BIER in Ethernet encapsulation.
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 August 2, 2019.
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Copyright Notice
Copyright (c) 2019 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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. IS-IS BIER Ethernet Encapsulation Sub-sub TLV . . . . . . 5
3.2. OSPFv2 BIER Ethernet Encapsulation Sub-TLV . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5.1. IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry . . . . 8
5.2. OSPFv2 Extended Prefix TLV Sub-TLVs Registry . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain multicast related per-flow
state. BIER can be supported in MPLS and non-MPLS networks.
[RFC8296] specifies a common BIER header format for both MPLS and
non-MPLS networks, though the first 20-bits of the BIER header
(referred as BIFT-id) is a "MPLS Label" in case of MPLS networks and
is a "domain-wide-unique-value" representing the combination of SD-
BSL-SI in case of non-MPLS networks.
[I-D.ietf-bier-non-mpls-bift-encoding] specifies two optional ways of
statically assigning domain-wide-unique mapping between BIFT-IDs and
SD-BSL-SI combination.
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However, BIER architecture [RFC8279] does NOT require domain-wide-
unique BIFT-IDs to be used (even for non-MPLS encapsulation). As
discussed in [I-D.zzhang-bier-rift], the BIFT-ID in case of non-MPLS
encapsulation can also just be a local 20-bit opaque value and
signaled just like in MPLS case.
As an example, suppose a particular BIER domain contains a SD (SD 0),
supports two BSLs (256 and 512), and contains 1024 BFRs. A BFR that
is provisioned for above SD, and that supports both BSLs, could
advertise the following set of BIFT-id's:
BIFT-id 1: corresponding to SD 0, BSL 256, SI 0.
BIFT-id 2: corresponding to SD 0, BSL 256, SI 1.
BIFT-id 3: corresponding to SD 0, BSL 256, SI 2.
BIFT-id 4: corresponding to SD 0, BSL 256, SI 3.
BIFT-id 5: corresponding to SD 0, BSL 512, SI 0.
BIFT-id 6: corresponding to SD 0, BSL 512, SI 1.
Notice that the example uses ranges of continuous BIFT-ids:
BIFT-id range [1 to 4] correspond to <SD 0, BSL 256>. The first
BIFT-id in the range correspond to SI=0, the second correspond to
SI=1, and so on.
BIFT-id range [5 to 6] correspond to <SD 0, BSL 512>. The first
BIFT-id in the range correspond to SI=0, the second correspond to
SI=1.
Strictly speaking, using contiguous range is not required, but it is
done for the purpose of simplified signaling similar to MPLS label
blocks (notice that locally assigning BIFT-ID ranges requires no
manual processing just like in the case of MPLS label block
allocation).
Processing and forwarding of BIER packets requires special software
and hardware capabilities. The BFRs supporting a BIER encapsulation
type MUST advertise this capability (along with the other required
parameters specific to the encapsulation) to the other routers in
BIER domain. This advertisement, for example, will enable the other
BFRs in the BIER domain in deciding, whether to include or exclude
the advertising router from the BAR and/or IPA algorithm while
computing the multicast path for a specific encapsulation type.
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[RFC8401] and [RFC8444] specifies the required extensions to the IS-
IS [RFC1195] and OSPFv2 [RFC2328] protocol respectively for the
distribution of BIER sub-domain information including the Sub-sub-TLV
required to support BIER in MPLS encapsulation for MPLS networks.
This document specifies the required extensions to the IS-IS
[RFC1195] and OSPFv2 [RFC2328] protocol for supporting BIER using
BIER in Ethernet encapsulation with dynamically and locally assigned
BIFT-IDs.
Support for other encapsulation types are outside the scope of this
document.
2. Terminology
Some of the terminology specified in [RFC8279] is replicated here and
extended by necessary definitions:
BIER: Bit Index Explicit Replication
(The overall architecture of forwarding multicast using a Bit
Position).
BIER-MPLS: BIER in MPLS encapsulation.
(Encapsulation of BIER header inside MPLS header in MPLS
networks).
BIER-ETH: BIER in Ethernet encapsulation.
(Encapsulation of BIER header inside Ethernet header
(EtherType=0xAB37) in non-MPLS networks).
BFR: Bit Forwarding Router (A router that participates in Bit Index
Multipoint Forwarding). A BFR is identified by a unique BFR-
prefix in a BIER domain.
BIFT: Bit Index Forwarding Table used to forward the BIER packets in
a domain.
BAR: BIER Algorithm. Used to calculate underlay nexthops
as defined by the BAR value.
IPA: IGP Algorithm. May be used to modify, enhance or replace the
calculation of underlay paths as defined by the BAR value
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2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Specification
A BIER sub-domain MAY support multiple BIER encapsulation types like
BIER-MPLS, BIER-ETH. The different encapsulation types supported by
a BFR in a sub-domain MUST share the same BFR-id. This would allow
the BFR's in transit to translate the encapsulation from one type to
the other while forwarding the packet in the BIER sub-domain.
When a BFIR/BFR supports multiple BIER encapsulation types, when
sending to a BIER neighbor it MUST use a type that the neighbor also
supports. If the neighbor also supports more than one encapsulation
type that this BFIR/BFR supports, the type selection could be a
matter of local policy and is outside the scope of this document.
3.1. IS-IS BIER Ethernet Encapsulation Sub-sub TLV
BIER Info sub-TLV defined in [RFC8401] is used to advertise the sub-
domain id, and other associated parameters of the sub-domain like
BFR-id, MT, BAR, IPA.
This document introduces new sub-sub-TLV under BIER Info sub-TLV to
advertise the ethernet encapsulation capability and other associated
parameters of the encapsulation.
This sub-sub-TLV carries the information for the BIER Ethernet
encapsulation including the BitString length supported for a certain
<MT,SD> pair.
It is advertised within the BIER Info sub-TLV defined in [RFC8401]
which in-turn is carried within the TLVs 235, 237 [RFC5120] or TLVs
135 [RFC5305], or TLV 236 [RFC5308].
This sub-sub-TLV MAY appear multiple times within a single BIER Info
sub-TLV. If the same BitString length is repeated in multiple BIER
Ethernet encapsulation sub-sub-TLVs inside the same BIER Info sub-
TLV, the BIER Info sub-TLV MUST be ignored.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI |BS Len | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 2 (suggested value - To be assigned by IANA).
Length: 4
Max SI: A 1 octet field encoding the Maximum Set Identifier
(Section 1 of [RFC8279]) used in the encapsulation for this BIER
subdomain for this BitString length. The first BIFT-id is for SI=0,
the second BIFT-id is for SI=1, etc. If the BIFT-id associated with
the Maximum Set Identifier exceeds the 20-bit range, the sub-sub-TLV
MUST be ignored.
Local BitString Length (BS Len): A 4 bit field encoding the
bitstring length (as per [RFC8296]) supported for the encapsulation.
BIFT-id: A 20 bit field encoding the first BIFT-id of the BIFT-id
range.
The "BIFT-id range" is the set of 20-bit values beginning with the
BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range
is allocated for each BitString length and sub-domain-id. These BIFT-
id's are used for BIER forwarding as described in [RFC8279] and
[RFC8296].
The size of the BIFT-id range is determined by the number of SI's
(Section 1 of [RFC8279]) that are used in the network. Each SI maps
to a single BIFT-id in the BIFT-id range: the first BIFT-id is for
SI=0, the second BIFT-id is for SI=1, etc.
If the BIFT-id associated with the Maximum Set Identifier exceeds
the 20-bit range, the BIER Ethernet Encapsulation Sub-sub-TLV
containing the error MUST be ignored.
3.2. OSPFv2 BIER Ethernet Encapsulation Sub-TLV
BIER Sub-TLV defined in [RFC8444] is used to advertise the sub-domain
id, and other associated parameters of the sub-domain like BFR-id,
MT, BAR, IPA.
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This document introduces new Sub-TLV under BIER Sub-TLV to advertise
the ethernet encapsulation capability and other associated parameters
of the encapsulation.
This Sub-TLV carries the information for the BIER Ethernet
encapsulation including the BitString length supported for a certain
<MT,SD> pair.
It is advertised within the BIER Sub-TLV defined in [RFC8444] which
in-turn is carried within the OSPFv2 Extended Prefix TLV defined in
[RFC7684].
This Sub-TLV MAY appear multiple times within a single BIER Sub-TLV.
If the same BitString length is repeated in multiple BIER Ethernet
encapsulation Sub-TLVs inside the same BIER Sub-TLV, the BIER Sub-TLV
MUST be ignored.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 11 (suggested value - To be assigned by IANA).
Length: 8
Max SI: A 1 octet field encoding the Maximum Set Identifier
(Section 1 of [RFC8279]) used in the encapsulation for this BIER
subdomain for this BitString length. The first BIFT-id is for SI=0,
the second BIFT-id is for SI=1, etc. If the BIFT-id associated with
the Maximum Set Identifier exceeds the 20-bit range, the sub-sub-TLV
MUST be ignored.
BIFT-id: A 3-octet field, where the 20 rightmost bits represent the
first BIFT-id in the BIFT-id range. The 4 leftmost bits MUST be
ignored.
The "BIFT-id range" is the set of 20-bit values beginning with the
BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range
is allocated for each BitString length and sub-domain-id. These BIFT-
id's are used for BIER forwarding as described in [RFC8279] and
[RFC8296].
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The size of the BIFT-id range is determined by the number of SI's
(Section 1 of [RFC8279]) that are used in the network. Each SI maps
to a single BIFT-id in the BIFT-id range: the first BIFT-id is for
SI=0, the second BIFT-id is for SI=1, etc.
If the BIFT-id associated with the Maximum Set Identifier exceeds
the 20-bit range, the BIER Ethernet Encapsulation Sub-sub-TLV
containing the error MUST be ignored.
Local BitString Length (BS Len): A 4 bit field encoding the
bitstring length (as per [RFC8296]) supported for the encapsulation.
Reserved: SHOULD be set to 0 on transmission and MUST be ignored on
reception.
4. Security Considerations
Security concerns for IS-IS are addressed in [RFC5304] and [RFC5310]
and the security concerns for IS-IS extensions for BIER are addressed
in [RFC8401]. This document introduces new sub-sub-TLV for the
already existing IS-IS TLVs defined for distributing the BIER sub-
domain information in [RFC8401]. It does not introduce any new
security risks to IS-IS.
Security concerns and required extensions for OSPFv2 are addressed in
[RFC2328] and [RFC7684] and the security concerns for OSPFv2
extensions for BIER are addressed in [RFC8444]. This document
introduces new Sub-TLV for the already existing OSPFv2 TLV defined
for distributing the BIER sub-domain information in [RFC8444]. It
does not introduce any new security risks to OSPFv2.
5. IANA Considerations
The document requests new allocations from the IANA registries as
follows
5.1. IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry
BIER Ethernet Encapsulation sub-sub-TLV: 2 (suggested)
5.2. OSPFv2 Extended Prefix TLV Sub-TLVs Registry
BIER Ethernet Encapsulation Sub-TLV: 11 (suggested)
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6. Acknowledgments
The author wants to thank Antonie Przygienda for his comments and
suggestions.
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>.
[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>.
7.2. Informative References
[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.
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[I-D.zzhang-bier-rift]
Zhang, Z., Ma, S., and Z. Zhang, "Supporting BIER with
RIFT", draft-zzhang-bier-rift-00 (work in progress), March
2018.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
DOI 10.17487/RFC5308, October 2008,
<https://www.rfc-editor.org/info/rfc5308>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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Authors' Addresses
Senthil Dhanaraj (editor)
Huawei
Email: senthil.dhanaraj.ietf@gmail.com
IJsbrand Wijnands
Cisco Systems, Inc.
Email: ice@cisco.com
Peter Psenak
Cisco Systems, Inc.
Email: ppsenak@cisco.com
Zhaohui Zhang
Juniper Networks.
Email: zzhang@juniper.net
Gang Yan
Huawei
Email: yangang@huawei.com
Jingrong Xie
Huawei
Email: xiejingrong@huawei.com
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