draft-ietf-ospf-mpls-elc-13.txt   draft-ietf-ospf-mpls-elc-14.txt 
OSPF Working Group X. Xu LSR Working Group X. Xu
Internet-Draft Alibaba Inc Internet-Draft Alibaba Inc
Intended status: Standards Track S. Kini Intended status: Standards Track S. Kini
Expires: October 19, 2020 Expires: November 29, 2020
P. Psenak P. Psenak
C. Filsfils C. Filsfils
S. Litkowski S. Litkowski
Cisco Systems, Inc. Cisco Systems, Inc.
M. Bocci M. Bocci
Nokia Nokia
April 17, 2020 May 28, 2020
Signaling Entropy Label Capability and Entropy Readable Label Depth Signaling Entropy Label Capability and Entropy Readable Label Depth
Using OSPF Using OSPF
draft-ietf-ospf-mpls-elc-13 draft-ietf-ospf-mpls-elc-14
Abstract Abstract
Multiprotocol Label Switching (MPLS) has defined a mechanism to load- Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
balance traffic flows using Entropy Labels (EL). An ingress Label balance traffic flows using Entropy Labels (EL). An ingress Label
Switching Router (LSR) cannot insert ELs for packets going into a Switching Router (LSR) cannot insert ELs for packets going into a
given Label Switched Path (LSP) unless an egress LSR has indicated given Label Switched Path (LSP) unless an egress LSR has indicated
via signaling that it has the capability to process ELs, referred to via signaling that it has the capability to process ELs, referred to
as the Entropy Label Capability (ELC), on that tunnel. In addition, as the Entropy Label Capability (ELC), on that LSP. In addition, it
it would be useful for ingress LSRs to know each LSR's capability for would be useful for ingress LSRs to know each LSR's capability for
reading the maximum label stack depth and performing EL-based load- reading the maximum label stack depth and performing EL-based load-
balancing, referred to as Entropy Readable Label Depth (ERLD). This balancing, referred to as Entropy Readable Label Depth (ERLD). This
document defines a mechanism to signal these two capabilities using document defines a mechanism to signal these two capabilities using
OSPFv2 and OSPFv3. OSPFv2 and OSPFv3 and BGP-LS.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 October 19, 2020. This Internet-Draft will expire on November 29, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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
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publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 25 skipping to change at page 2, line 25
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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 3 3. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 3
3.1. Advertising ELC Using OSPFv2 . . . . . . . . . . . . . . 3 3.1. Advertising ELC Using OSPFv2 . . . . . . . . . . . . . . 4
3.2. Advertising ELC Using OSPFv3 . . . . . . . . . . . . . . 4 3.2. Advertising ELC Using OSPFv3 . . . . . . . . . . . . . . 4
4. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4 4. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4
5. Signaling ELC and ERLD in BGP-LS . . . . . . . . . . . . . . 4 5. Signaling ELC and ERLD in BGP-LS . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 8 10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
[RFC6790] describes a method to load-balance Multiprotocol Label [RFC6790] describes a method to load-balance Multiprotocol Label
Switching (MPLS) traffic flows using Entropy Labels (EL). It also Switching (MPLS) traffic flows using Entropy Labels (EL). It also
introduces the concept of Entropy Label Capability (ELC) and defines introduces the concept of Entropy Label Capability (ELC) and defines
the signaling of this capability via MPLS signaling protocols. the signaling of this capability via MPLS signaling protocols.
Recently, mechanisms have been defined to signal labels via link- Recently, mechanisms have been defined to signal labels via link-
state Interior Gateway Protocols (IGP) such as OSPFv2 [RFC8665] and state Interior Gateway Protocols (IGP) such as OSPFv2 [RFC8665] and
OSPFv3 [RFC8666]. This draft defines a mechanism to signal the ELC OSPFv3 [RFC8666]. This draft defines a mechanism to signal the ELC
using OSPFv2 and OSPFv3. using OSPFv2 and OSPFv3.
In cases where LSPs are used (e.g., SR-MPLS [RFC8660], it would be In cases where Segment Routing (SR) is used with the MPLS Data Plane
useful for ingress LSRs to know each intermediate LSR's capability of (e.g., SR-MPLS [RFC8660]), it would be useful for ingress LSRs to
reading the maximum label stack depth and performing EL-based load- know each intermediate LSR's capability of reading the maximum label
balancing. This capability, referred to as Entropy Readable Label stack depth and performing EL-based load-balancing. This capability,
Depth (ERLD) as defined in [RFC8662] may be used by ingress LSRs to referred to as Entropy Readable Label Depth (ERLD) as defined in
determine the position of the EL label in the stack, and whether it's [RFC8662], may be used by ingress LSRs to determine the position of
necessary to insert multiple ELs at different positions in the label the EL label in the stack, and whether it is necessary to insert
stack. multiple ELs at different positions in the label stack. This
document defines a mechanism to signal the ERLD using OSPFv2 and
OSPFv3.
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC6790], and [RFC8662]. This memo makes use of the terms defined in [RFC6790], and [RFC8662].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
skipping to change at page 3, line 38 skipping to change at page 3, line 40
originator. Similarly, in a multi domain network, the identity of originator. Similarly, in a multi domain network, the identity of
the prefix originator and its capabilities may not be known to the the prefix originator and its capabilities may not be known to the
ingress LSR. ingress LSR.
If a router has multiple interfaces, the router MUST NOT announce ELC If a router has multiple interfaces, the router MUST NOT announce ELC
unless all of its interfaces are capable of processing ELs. unless all of its interfaces are capable of processing ELs.
If the router supports ELs on all of its interfaces, it SHOULD If the router supports ELs on all of its interfaces, it SHOULD
advertise the ELC with every local host prefix it advertises in OSPF. advertise the ELC with every local host prefix it advertises in OSPF.
When an OSPF Area Border Router (ABR) distributes information between The ELC signaling MUST be preserved when an OSPF Area Border Router
connected areas it MUST preserve the ELC setting. (ABR) distributes information between areas. To do so, an ABR MUST
originate an OSPFv2 Extended Prefix Opaque LSA [RFC7684] including
the received ELC setting.
When an OSPF Autonomous System Boundary Router (ASBR) redistributes a When an OSPF Autonomous System Boundary Router (ASBR) redistributes a
prefix from another instance of the OSPF or from some other protocol, prefix from another instance of OSPF or from some other protocol, it
it SHOULD preserve the ELC signaling for the prefix. The exact SHOULD preserve the ELC signaling for the prefix if it exists. To do
mechanism used to exchange ELC between protocol instances on the ASBR so, an ASBR SHOULD originate an Extended Prefix Opaque LSA [RFC7684]
is outside of the scope of this document. including the ELC setting of the redistributed prefix. The flooding
scope of the Extended Prefix Opaque LSA MUST match the flooding scope
of the LSA that an ASBR originates as a result of the redistribution.
The exact mechanism used to exchange ELC between protocol instances
on an ASBR is outside of the scope of this document.
3.1. Advertising ELC Using OSPFv2 3.1. Advertising ELC Using OSPFv2
[RFC7684] defines the OSPFv2 Extended Prefix TLV to advertise [RFC7684] defines the OSPFv2 Extended Prefix TLV to advertise
additional attributes associated with a prefix. The OSPFv2 Extended additional attributes associated with a prefix. The OSPFv2 Extended
Prefix TLV includes a one octet Flags field. A new flag in the Flags Prefix TLV includes a one-octet Flags field. A new flag in the Flags
field is used to signal the ELC for the prefix: field is used to signal the ELC for the prefix:
0x20 - E-Flag (ELC Flag): Set by the advertising router to 0x20 - E-Flag (ELC Flag): Set by the advertising router to
indicate that the prefix originator is capable of processing ELs. indicate that the prefix originator is capable of processing ELs.
3.2. Advertising ELC Using OSPFv3 3.2. Advertising ELC Using OSPFv3
[RFC5340] defines the OSPFv3 PrefixOptions field to indicate [RFC5340] defines the OSPFv3 PrefixOptions field to indicate
capabilities associated with a prefix. A new bit in the OSPFv3 capabilities associated with a prefix. A new bit in the OSPFv3
PrefixOptions is used to signal the ELC for the prefix: PrefixOptions is used to signal the ELC for the prefix:
0x04 - E-Flag (ELC Flag): Set by the advertising router to 0x40 - E-Flag (ELC Flag): Set by the advertising router to
indicate that the prefix originator is capable of processing ELs. indicate that the prefix originator is capable of processing ELs.
The ELC signaling MUST be preserved when an OSPFv3 Area Border
Router (ABR) distributes information between areas. The setting
of the ELC Flag in the Inter-Area-Prefix-LSA [RFC5340] or in the
Inter-Area-Prefix TLV [RFC8362], generated by an ABR, MUST be the
same as the value the ELC Flag associated with the prefix in the
source area.
When an OSPFv3 Autonomous System Boundary Router (ASBR)
redistributes a prefix from another instance of OSPFv3 or from
some other protocol, it SHOULD preserve the ELC signaling for the
prefix if it exists. The setting of the ELC Flag in the AS-
External-LSA, NSSA-LSA [RFC5340] or in the External-Prefix TLV
[RFC8362], generated by an ASBR, MUST be the same as the value of
the ELC Flag associated with the prefix in the source domain. The
exact mechanism used to exchange ELC between protocol instances on
the ASBR is outside of the scope of this document.
4. Advertising ERLD Using OSPF 4. Advertising ERLD Using OSPF
The ERLD is advertised in a Node MSD sub-TLV [RFC8476] using the The ERLD is advertised in a Node MSD TLV [RFC8476] using the ERLD-MSD
ERLD-MSD type defined in [I-D.ietf-isis-mpls-elc]. type defined in [I-D.ietf-isis-mpls-elc].
If a router has multiple interfaces with different capabilities of If a router has multiple interfaces with different capabilities of
reading the maximum label stack depth, the router MUST advertise the reading the maximum label stack depth, the router MUST advertise the
smallest one. smallest value found across all of its interfaces.
The absence of ERLD-MSD advertisements indicates only that the The absence of ERLD-MSD advertisements indicates only that the
advertising node does not support advertisement of this capability. advertising node does not support advertisement of this capability.
When the ERLD MSD-Type is received in the OSPFv2 or OSPFv3 Link MSD When the ERLD-MSD type is received in the OSPFv2 or OSPFv3 Link MSD
Sub-TLV, it MUST be ignored. Sub-TLV [RFC8476], it MUST be ignored.
The considerations for advertising the ERLD are specified in The considerations for advertising the ERLD are specified in
[RFC8662]. [RFC8662].
5. Signaling ELC and ERLD in BGP-LS 5. Signaling ELC and ERLD in BGP-LS
The OSPF extensions defined in this document can be advertised via The OSPF extensions defined in this document can be advertised via
BGP-LS [RFC7752] using existing BGP-LS TLVs. BGP-LS (Distribution of Link-State and TE Information Using BGP)
[RFC7752] using existing BGP-LS TLVs.
The ELC is advertised using the Prefix Attribute Flags TLV as defined The ELC is advertised using the Prefix Attribute Flags TLV as defined
in [I-D.ietf-idr-bgp-ls-segment-routing-ext]. in [I-D.ietf-idr-bgp-ls-segment-routing-ext].
The ERLD-MSD is advertised using the Node MSD TLV as defined in The ERLD-MSD is advertised using the Node MSD TLV as defined in
[I-D.ietf-idr-bgp-ls-segment-routing-msd]. [I-D.ietf-idr-bgp-ls-segment-routing-msd].
6. IANA Considerations 6. IANA Considerations
Early allocation has been done by IANA for this document as follows: Early allocation has been done by IANA for this document as follows:
- Flag 0x20 in the OSPFv2 Extended Prefix TLV Flags registry has - Flag 0x20 in the OSPFv2 Extended Prefix TLV Flags registry has
been assigned to the E-Flag (ELC Flag). IANA is asked to update been allocated by IANA to the E-Flag (ELC Flag).
the registry to reflect the name used in this document: E-Flag
(ELC Flag).
- Bit 0x04 in the "OSPFv3 Prefix Options (8 bits)" registry has - Bit 0x40 in the "OSPFv3 Prefix Options (8 bits)" registry has
been assigned to the E-Flag (ELC Flag). IANA is asked to update been allocated by IANA to the E-Flag (ELC Flag).
the registry to reflect the name used in this document: E-Flag
(ELC Flag).
7. Security Considerations 7. Security Considerations
This document specifies the ability to advertise additional node This document specifies the ability to advertise additional node
capabilities using OSPF and BGP-LS. As such, the security capabilities using OSPF and BGP-LS. As such, the security
considerations as described in [RFC5340], [RFC7770], [RFC7752], considerations as described in [RFC5340], [RFC7770], [RFC7752],
[RFC7684], [RFC8476], [RFC8662], [RFC7684], [RFC8476], [RFC8662],
[I-D.ietf-idr-bgp-ls-segment-routing-ext] and [I-D.ietf-idr-bgp-ls-segment-routing-ext] and
[I-D.ietf-idr-bgp-ls-segment-routing-msd] are applicable to this [I-D.ietf-idr-bgp-ls-segment-routing-msd] are applicable to this
document. document.
Incorrectly setting the E flag during origination, propagation or Incorrectly setting the E flag during origination, propagation or
redistribution may lead to black-holing of the traffic on the egress redistribution may lead to poor or no load-balancing of the MPLS
node. traffic or black-holing of the MPLS traffic on the egress node.
Incorrectly setting of the ERLD value may lead to poor or no load- Incorrectly setting of the ERLD value may lead to poor or no load-
balancing of the traffic. balancing of the MPLS traffic.
8. Contributors 8. Contributors
The following people contributed to the content of this document and The following people contributed to the content of this document and
should be considered as co-authors: should be considered as co-authors:
Gunter Van de Velde (editor) Gunter Van de Velde (editor)
Nokia Nokia
Antwerp Antwerp
BE BE
skipping to change at page 6, line 44 skipping to change at page 7, line 9
[I-D.ietf-idr-bgp-ls-segment-routing-ext] [I-D.ietf-idr-bgp-ls-segment-routing-ext]
Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H., Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
and M. Chen, "BGP Link-State extensions for Segment and M. Chen, "BGP Link-State extensions for Segment
Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16 Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
(work in progress), June 2019. (work in progress), June 2019.
[I-D.ietf-idr-bgp-ls-segment-routing-msd] [I-D.ietf-idr-bgp-ls-segment-routing-msd]
Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G., Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G.,
and N. Triantafillis, "Signaling MSD (Maximum SID Depth) and N. Triantafillis, "Signaling MSD (Maximum SID Depth)
using Border Gateway Protocol - Link State", draft-ietf- using Border Gateway Protocol - Link State", draft-ietf-
idr-bgp-ls-segment-routing-msd-16 (work in progress), idr-bgp-ls-segment-routing-msd-18 (work in progress), May
March 2020. 2020.
[I-D.ietf-isis-mpls-elc] [I-D.ietf-isis-mpls-elc]
Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S., Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S.,
and M. Bocci, "Signaling Entropy Label Capability and and M. Bocci, "Signaling Entropy Label Capability and
Entropy Readable Label Depth Using IS-IS", draft-ietf- Entropy Readable Label Depth Using IS-IS", draft-ietf-
isis-mpls-elc-11 (work in progress), March 2020. isis-mpls-elc-12 (work in progress), April 2020.
[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>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>. <https://www.rfc-editor.org/info/rfc5340>.
skipping to change at page 7, line 45 skipping to change at page 8, line 5
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <https://www.rfc-editor.org/info/rfc7770>. February 2016, <https://www.rfc-editor.org/info/rfc7770>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak, [RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
"Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476, "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
DOI 10.17487/RFC8476, December 2018, DOI 10.17487/RFC8476, December 2018,
<https://www.rfc-editor.org/info/rfc8476>. <https://www.rfc-editor.org/info/rfc8476>.
[RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., [RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy Label for Source Shakir, R., and J. Tantsura, "Entropy Label for Source
Packet Routing in Networking (SPRING) Tunnels", RFC 8662, Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
DOI 10.17487/RFC8662, December 2019, DOI 10.17487/RFC8662, December 2019,
<https://www.rfc-editor.org/info/rfc8662>. <https://www.rfc-editor.org/info/rfc8662>.
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