< draft-ietf-bier-bar-ipa-03.txt   draft-ietf-bier-bar-ipa-04.txt >
BIER Z. Zhang BIER Z. Zhang
Internet-Draft A. Przygienda Internet-Draft A. Przygienda
Intended status: Standards Track Juniper Networks Updates: 8401,8444 (if approved) Juniper Networks
Expires: May 20, 2019 A. Dolganow Intended status: Standards Track A. Dolganow
H. Bidgoli Expires: November 30, 2019 H. Bidgoli
Nokia Nokia
I. Wijnands I. Wijnands
Cisco Systems Cisco Systems
A. Gulko A. Gulko
Thomson Reuters Thomson Reuters
November 16, 2018 May 29, 2019
BIER Underlay Path Calculation Algorithm and Constraints BIER Underlay Path Calculation Algorithm and Constraints
draft-ietf-bier-bar-ipa-03 draft-ietf-bier-bar-ipa-04
Abstract Abstract
This document specifies general rules for interaction between the BAR This document specifies general rules for interaction between the BAR
(BIER Algorithm) and IPA (IGP Algorithm) fields defined in ISIS/ (BIER Algorithm) and IPA (IGP Algorithm) fields defined in ISIS/
OSPFv2 Extensions for BIER. OSPFv2 Extensions for BIER. The semantics for the BAR and IPA fields
(when both or any of them is non-zero) defined in this document
updates the semantics defined in RFC8444/RFC8401.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119. document are to be interpreted as described in RFC2119.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 20, 2019. This Internet-Draft will expire on November 30, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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packets with a BIER encapsulation header are forwarded to the packets with a BIER encapsulation header are forwarded to the
neighbors on the underlay paths towards the BFERs. For each sub- neighbors on the underlay paths towards the BFERs. For each sub-
domain, the paths are calculated in the underlay topology for the domain, the paths are calculated in the underlay topology for the
sub-domain, following a calculation algorithm specific to the sub- sub-domain, following a calculation algorithm specific to the sub-
domain. The <topology, algorithm> could be congruent or incongruent domain. The <topology, algorithm> could be congruent or incongruent
with unicast. The topology could be a default topology, a multi- with unicast. The topology could be a default topology, a multi-
topology [RFC5120] topology. The algorithm could be a generic IGP topology [RFC5120] topology. The algorithm could be a generic IGP
algorithm (e.g. SPF) or could be a BIER specific one defined in the algorithm (e.g. SPF) or could be a BIER specific one defined in the
future. future.
In [RFC8401] and [I-D.ietf-bier-ospf-bier-extensions], an 8-bit BAR In [RFC8401] and [RFC8444], an 8-bit BAR (BIER Algorithm) field and
(BIER Algorithm) field and 8-bit IPA (IGP Algorithm) field are 8-bit IPA (IGP Algorithm) field are defined to signal the BIER
defined to signal the BIER specific algorithm and generic IGP specific algorithm and generic IGP Algorithm respectively and only
Algorithm respectively and only value 0 is allowed for both fields in value 0 is allowed for both fields in those two documents. This
those two documents. This document specifies the general rules for document specifies the general rules for the two fields and their
the two fields and their interaction when either or both fields are interaction when either or both fields are not 0, and updates their
not 0. semantics defined in [RFC8444] and [RFC8401].
2. General Rules for the BAR and IPA fields 2. General Rules for the BAR and IPA fields
For a particular sub-domain, all routers SHOULD be provisioned with For a particular sub-domain, all routers SHOULD be provisioned with
and signal the same BAR and IPA values. When a BFR discovers another and signal the same BAR and IPA values. When a BFR discovers another
BFR advertising different BAR or IPA value from its own provisioned, BFR advertising different BAR or IPA value from its own provisioned,
it MUST treat the advertising BFR as incapable of supporting BIER for it MUST treat the advertising BFR as incapable of supporting BIER for
the sub-domain. How incapable routers are handled is outside the the sub-domain. How incapable routers are handled is outside the
scope of this document. scope of this document.
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A. If BA is NULL, AG is set to RA. A. If BA is NULL, AG is set to RA.
B. If BA is not NULL, AG is set to BA. B. If BA is not NULL, AG is set to BA.
4. Run AG on RC(BC(X)). 4. Run AG on RC(BC(X)).
2.1. When BAR Is Not Used 2.1. When BAR Is Not Used
The BIER Algorithm registry established by [RFC8401] and also used in The BIER Algorithm registry established by [RFC8401] and also used in
[I-D.ietf-bier-ospf-bier-extensions] has value 0 for "No BIER [RFC8444] has value 0 for "No BIER specific algorithm is used". That
specific algorithm is used". That translates to NULL BA and NULL BC. translates to NULL BA and NULL BC. Following the rules defined
Following the rules defined above, the IPA value alone identifies the above, the IPA value alone identifies the calculation algorithm and
calculation algorithm and constraints to be used for a particular constraints to be used for a particular sub-domain when BAR is 0.
sub-domain when BAR is 0.
2.2. Exceptions/Extensions to the General Rules 2.2. Exceptions/Extensions to the General Rules
Exceptions or extensions to the above general rules may be specified Exceptions or extensions to the above general rules may be specified
in the future for specific BAR and/or IPA values. When that happens, in the future for specific BAR and/or IPA values. When that happens,
compatibility with defined BAR and/or IPA values and semantics need compatibility with defined BAR and/or IPA values and semantics need
to be specified. to be specified.
3. IANA Considerations 3. IANA Considerations
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The authors thanks Alia Atlas, Eric Rosen, Senthil Dhanaraj and many The authors thanks Alia Atlas, Eric Rosen, Senthil Dhanaraj and many
others for their suggestions and comments. In particular, the BCBA/ others for their suggestions and comments. In particular, the BCBA/
RCRA representation for the interaction rules is based on Alia's RCRA representation for the interaction rules is based on Alia's
write-up. write-up.
5. References 5. References
5.1. Normative References 5.1. Normative References
[I-D.ietf-bier-ospf-bier-extensions]
Psenak, P., Kumar, N., Wijnands, I., Dolganow, A.,
Przygienda, T., Zhang, Z., and S. Aldrin, "OSPFv2
Extensions for BIER", draft-ietf-bier-ospf-bier-
extensions-18 (work in progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z.
Zhang, "Bit Index Explicit Replication (BIER) Support via Zhang, "Bit Index Explicit Replication (BIER) Support via
IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018,
<https://www.rfc-editor.org/info/rfc8401>. <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>.
5.2. Informative References 5.2. Informative References
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008, DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>. <https://www.rfc-editor.org/info/rfc5120>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
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