Internet DRAFT - draft-zwx-bier-te-isis-extensions
draft-zwx-bier-te-isis-extensions
BIER Z. Zhang
Internet-Draft Y. Wei
Intended status: Standards Track B. Xu
Expires: 25 January 2023 ZTE Corporation
24 July 2022
IS-IS extensions for BIER-TE (Tree Engineering for Bit Index Explicit
Replication) with MPLS and non-MPLS Encapsulation
draft-zwx-bier-te-isis-extensions-01
Abstract
This document describes the IS-IS protocol extension that is required
for BIER-TE with MPLS and non-MPLS encapsulation.
Status of This Memo
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This Internet-Draft will expire on 25 January 2023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Flooding of the BIER-TE Encapsulation Information in IS-IS . 3
3.1. MPLS Encapsulation Sub-sub-TLV . . . . . . . . . . . . . 3
3.2. Non-MPLS Encapsulation Sub-sub-TLV . . . . . . . . . . . 4
3.2.1. BIER-TE IPv6 Encapsulation Advertisement . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[I-D.ietf-bier-te-arch] describes per-packet stateless strict and
loose path steered replication and forwarding for "Bit Index Explicit
Replication" (BIER, [RFC8279]) packets. It is called BIER Tree
Engineering (BIER-TE) and is intended to be used as the path steering
mechanism for Traffic Engineering with BIER.
BIER-TE introduces a new semantic for "bit positions" (BP) of link.
[I-D.ietf-bier-te-isis] describes IS-IS extensions for distributing
BitPositions configured on the links in "Bit Index Explicit
Replication Traffic Engineering" (BIER-TE) domain.
As described in section 2.3 in [I-D.ietf-bier-te-arch], BIER-TE
inherits the encapsulation supporting from BIER unchanged. The
encapsulation defined in [RFC8296], which specifies a common header
format for both MPLS and non-MPLS networks, though the first 20-bits
(referred to as BIFT-id) of the header is an "MPLS Label" in case of
MPLS networks and is a local 20-bit opaque value in case of non-MPLS
networks.
As described in section 4.3 of [I-D.ietf-bier-te-arch], it is
necessary to distinguish the BIER and BIER-TE packet and forwarding.
like [RFC8401] and [I-D.ietf-bier-lsr-non-mpls-extensions], the MPLS
and non-MPLS encapsulation needs to be advertised for BIER-TE packet
encapsulation.
This document describes the IS-IS protocol extension that is required
for BIER-TE with MPLS and non-MPLS encapsulation associated with link
BitPosition distributing.
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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 [RFC2119].
2. Terminology
This document does not introduce more terminologies than [RFC8279],
[RFC8296], [RFC8401], [I-D.ietf-bier-te-arch] and
[I-D.ietf-bier-te-isis].
3. Flooding of the BIER-TE Encapsulation Information in IS-IS
[I-D.ietf-bier-te-isis] defines a BIER-TE Info Sub-TLV to distribute
the Link BitPosition information about the link. This document
defines the MPLS Encapsulation Sub-sub-TLV and the Non-MPLS
Encapsulation Sub-sub-TLV associate with the BIER-TE Sub-TLV to carry
the MPLS and non-MPLS encapsulation information.
In case both of the two encapsulation sub-sub-TLVs are advertised by
one node, the label in MPLS encapsulation sub-sub-TLV and BIFT-id in
non-MPLS encapsulation sub-sub-TLV SHOULD NOT be overlapped.
3.1. MPLS Encapsulation Sub-sub-TLV
The following description is the almost same with [RFC8401] since
[I-D.ietf-bier-te-arch] inherit the encapsulation of BIER header.
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 | Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type: TBD1 (To be assigned by IANA).
Length: 2-octet.
Max SI: A 1-octet field encoding the maximum Set Identifier (SI)
(see Section 1 of [RFC8279]) used in the encapsulation for this
BIER sub-domain for this BitString length.
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Label: A 3-octet field, where the 20 rightmost bits represent the
first label in the label range. The 4 leftmost bits MUST be
ignored.
BS Len (BitString Length): A 4-bit field encoding the supported
BitString length associated with this BFR-prefix. The values
allowed in this field are specified in Section 2 of [RFC8296].
Reserved: SHOULD be set to 0 on transmission and MUST be ignored
on reception.
The "label range" is the set of labels beginning with the Label and
ending with (Label + (Max SI)). A unique label range is allocated
for each BitString length and sub-domain-id.
The size of the label range is determined by the number of SIs
(Section 1 of [RFC8279]) that are used in the network. Each SI maps
to a single label in the label range: the first label is for SI=0,
the second label is for SI=1, etc.
If the label associated with the Maximum Set Identifier exceeds the
20-bit range, the BIER MPLS Encapsulation Sub-TLV containing the
error MUST be ignored.
If the BitString length is set to a value that does not match any of
the allowed values specified in [RFC8296], the BIER MPLS
Encapsulation Sub-TLV containing the error 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)).
The flooding scope of this information is the same with section 5 in
[RFC8401].
3.2. Non-MPLS Encapsulation Sub-sub-TLV
The following description is the almost same with section 3.1 in
[I-D.ietf-bier-lsr-non-mpls-extensions] since [I-D.ietf-bier-te-arch]
inherit the encapsulation of BIER header.
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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 | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type: TBD2 (To be assigned by IANA).
Length: 2-octet.
Max SI: A 1-octet field encoding the maximum Set Identifier (SI)
(see Section 1 of [RFC8279]) used in the encapsulation for this
BIER sub-domain for this BitString length.
BIFT-id: A 3-octet field, where the 20 rightmost bits represent
the first label in the label range. The 4 leftmost bits MUST be
ignored.
BS Len (BitString Length): A 4-bit field encoding the supported
BitString length associated with this BFR-prefix. The values
allowed in this field are specified in Section 2 of [RFC8296].
Reserved: SHOULD be set to 0 on transmission and MUST be ignored
on reception.
The BIFT-id range, limitation and flooding scope is the same with the
MPLS encapsulation sub-sub-TLV.
3.2.1. BIER-TE IPv6 Encapsulation Advertisement
As described in section 4 of [I-D.ietf-bier-bierin6], which describes
how the existing BIER encapsulation specified in [RFC8296] works in a
non-MPLS IPv6 network, a node that requires IPv6 encapsulation MUST
advertise the BIER-TE IPv6 encapsulation sub-sub-sub-TLV, which
follows the Non-MPLS Encapsulation Sub-sub-TLV, according to local
configuration or policy in the BIER domain to request other BFRs to
always use IPv6 encapsulation.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
Type: TBD3 (To be assigned by IANA).
Length: 0.
4. IANA Considerations
TBD.
5. Security Considerations
This document does not introduce more security considerations than
[I-D.ietf-bier-te-arch] and [I-D.ietf-bier-te-isis].
6. References
6.1. Normative References
[I-D.ietf-bier-bierin6]
Zhang, Z., Zhang, Z., Wijnands, I., Mishra, M., Bidgoli,
H., and G. Mishra, "Supporting BIER in IPv6 Networks
(BIERin6)", Work in Progress, Internet-Draft, draft-ietf-
bier-bierin6-04, March 2022,
<https://www.ietf.org/archive/id/draft-ietf-bier-
bierin6-04.txt>.
[I-D.ietf-bier-lsr-non-mpls-extensions]
Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang,
Z., and J. Xie, "LSR Extensions for BIER non-MPLS
Encapsulation", Work in Progress, Internet-Draft, draft-
ietf-bier-lsr-non-mpls-extensions-00, March 2022,
<https://www.ietf.org/archive/id/draft-ietf-bier-lsr-non-
mpls-extensions-00.txt>.
[I-D.ietf-bier-te-arch]
Eckert, T., Menth, M., and G. Cauchie, "Tree Engineering
for Bit Index Explicit Replication (BIER-TE)", Work in
Progress, Internet-Draft, draft-ietf-bier-te-arch-13, 25
April 2022, <https://www.ietf.org/archive/id/draft-ietf-
bier-te-arch-13.txt>.
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[I-D.ietf-bier-te-isis]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "IS-IS Extensions for BIER-TE", Work
in Progress, Internet-Draft, draft-ietf-bier-te-isis-00,
25 January 2022, <https://www.ietf.org/archive/id/draft-
ietf-bier-te-isis-00.txt>.
[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", DOI 10.17487/RFC8401, RFC 8401, June 2018,
<https://www.rfc-editor.org/info/rfc8401>.
Authors' Addresses
Zheng Zhang
ZTE Corporation
China
Email: zhang.zheng@zte.com.cn
Yuehua Wei
ZTE Corporation
China
Email: wei.yuehua@zte.com.cn
Benchong Xu
ZTE Corporation
China
Email: xu.benchong@zte.com.cn
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