draft-ietf-ospf-mpls-elc-08.txt   draft-ietf-ospf-mpls-elc-09.txt 
OSPF Working Group X. Xu OSPF 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: November 14, 2019 Expires: March 6, 2020
P. Psenak P. Psenak
C. Filsfils C. Filsfils
Cisco Cisco
S. Litkowski S. Litkowski
Orange Orange
May 13, 2019 September 3, 2019
Signaling Entropy Label Capability and Entropy Readable Label-stack Signaling Entropy Label Capability and Entropy Readable Label-stack
Depth Using OSPF Depth Using OSPF
draft-ietf-ospf-mpls-elc-08 draft-ietf-ospf-mpls-elc-09
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 tunnel unless an egress LSR has indicated via signaling that it given tunnel unless an egress LSR has indicated via signaling that it
has the capability of processing ELs, referred to as Entropy Label has the capability to process ELs, referred to as Entropy Label
Capability (ELC), on that tunnel. In addition, it would be useful Capability (ELC), on that tunnel. In addition, it would be useful
for ingress LSRs to know each LSR's capability of reading the maximum for ingress LSRs to know each LSR's capability of reading the maximum
label stack depth and performing EL-based load-balancing, referred to label stack depth and performing EL-based load-balancing, referred to
as Entropy Readable Label Depth (ERLD), in the cases where stacked as Entropy Readable Label Depth (ERLD). This document defines a
LSPs are used. This document defines a mechanisms to signal these mechanism to signal these two capabilities using OSPF and OSPFv3.
two capabilities using OSPF and OSPFv3. These mechanisms are These mechanism is particularly useful in the environment where
particularly useful in the environment where Segment Routing (SR) is Segment Routing (SR) is used, where label advertisements are done via
used, where label advertisements are done via protocols like OSPF and protocols like OSPF and OSPFv3.
OSPFv3.
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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [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 November 14, 2019. This Internet-Draft will expire on March 6, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 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
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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 . . . . . . . . . . . . . . 4 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. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. BGP-LS Extension . . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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 signalings of this capability via MPLS signaling protocols. the signaling of this capability via MPLS signaling protocols.
Recently, mechanisms are being defined to signal labels via link- Recently, mechanisms have been defined to signal labels via link-
state Interior Gateway Protocols (IGP) such as OSPF state Interior Gateway Protocols (IGP) such as OSPF
[I-D.ietf-ospf-segment-routing-extensions]. In such scenario, the [I-D.ietf-ospf-segment-routing-extensions]. In such scenarios, the
signaling mechanisms defined in [RFC6790] are inadequate. This draft signaling mechanisms defined in [RFC6790] are inadequate. This draft
defines a mechanism to signal the ELC using OSPF. This mechanism is defines a mechanism to signal the ELC using OSPF. This mechanism is
useful when the label advertisement is also done via OSPF. useful when the label advertisement is also done via OSPF.
In addition, in the cases where stacked LSPs are used for whatever In addition, in the cases where stacked LSPs are used for whatever
reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it
would be useful for ingress LSRs to know each intermediate LSR's would be useful for ingress LSRs to know each intermediate LSR's
capability of reading the maximum label stack depth and performing capability of reading the maximum label stack depth and performing
EL-based load-balancing. This capability, referred to as Entropy EL-based load-balancing. This capability, referred to as Entropy
Readable Label Depth (ERLD) as defined in Readable Label Depth (ERLD) as defined in
[I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to [I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to
determine whether it's necessary to insert an EL for a given LSP of determine the position of the EL label in the stack, and whether it's
the stacked LSP tunnel in the case where there has already been at necessary to insert multiple ELs at different positions in the label
least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label]. stack.
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC6790] and [RFC7770]. This document makes use of the terms defined in [RFC6790] and
[RFC7770].
3. Advertising ELC Using OSPF 3. Advertising ELC Using OSPF
Even though ELC is a property of the node, in some cases it is Even though ELC is a property of the node, in some cases it is
advantageous to associate and advertise the ELC with the prefix. In advantageous to associate and advertise the ELC with the prefix. In
multi-area network, routers may not know the identity of the prefix multi-area networks, routers may not know the identity of the prefix
originator in the remote area, or may not know the capabilities of originator in a remote area, or may not know the capabilities of such
such originator. Similarly in the multi domain network, the identity originator. Similarly, in a multi domain network, the identity of
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 line cards, the router MUST NOT announce ELC If a router has multiple line cards, the router MUST NOT announce ELC
unless all of its linecards are capable of processing ELs. unless all of its line-cards are capable of processing ELs.
If the router support ELs on all of its line cards, it SHOULD If the router supports ELs on all of its line cards, 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) advertises the prefix to the When an OSPF Area Border Router (ABR) advertises the prefix to the
connected area based on the intra-area or inter-area prefix that is connected area based on the intra-area or inter-area prefix that is
reachable in some other area, it MUST preserve the ELC signalling for reachable in some other area, it MUST preserve the ELC signalling for
such prefix. such prefix.
When an OSPF Autonomous System Boundary Router (ASBR) redistributes When an OSPF Autonomous System Boundary Router (ASBR) redistributes
the prefix from other instance of the OSPF or from some other the prefix from another instance of the OSPF or from some other
protocol, it SHOULD preserve the ELC signalling for the prefix. protocol, it SHOULD preserve the ELC signaling for the prefix. The
Exact mechanism on how to exchange ELC between protocol instances on exact mechanism used to exchange ELC between protocol instances on
the ASBR is outside of the scope of this document and is the ASBR is outside of the scope of this document and is
implementation specific. implementation specific.
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 the prefix. The OSPFv2 additional attributes associated with a prefix. The OSPFv2 Extended
Extended Prefix TLV includes a one octet Flags field. A new bit in Prefix TLV includes a one octet Flags field. A new flag in the Flags
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 that is advertised along [RFC5340] defines the OSPFv3 PrefixOptions that are advertised along
with the prefix. A new bit in the OSPFV3 PrefixOptions is used to with the prefix. A new bit in the OSPFV3 PrefixOptions is used to
signal the ELC for the prefix: signal the ELC for the prefix:
0x04 - E-Flag (ELC Flag): Set by the advertising router to 0x04 - 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.
4. Advertising ERLD Using OSPF 4. Advertising ERLD Using OSPF
A new MSD-type of the Node MSD sub-TLV A new MSD-type of the Node MSD sub-TLV
[I-D.ietf-isis-segment-routing-msd], called ERLD is defined to [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to
advertise the ERLD of a given router. The scope of the advertisement advertise the ERLD of a given router. The scope of the advertisement
depends on the application. depends on the application.
Assignment of a MSD-Type for ERLD is defined in Assignment of a MSD-Type for ERLD is defined in
[I-D.ietf-isis-mpls-elc]. [I-D.ietf-isis-mpls-elc].
If a router has multiple linecards with different capabilities of If a router has multiple line-cards with different capabilities for
reading the maximum label stack deepth, the router MUST advertise the reading the maximum label stack depth, the router MUST advertise the
smallest one. smallest one.
5. Acknowledgements 5. Acknowledgements
The authors would like to thank Yimin Shen, George Swallow, Acee The authors would like to thank Yimin Shen, George Swallow, Acee
Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura , Bruno Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura , Bruno
Decraene and Carlos Pignataro for their valuable comments. Decraene and Carlos Pignataro for their valuable comments.
6. IANA Considerations 6. BGP-LS Extension
This document requests IANA to allocate one bit from the OSPFv2 The OSPF extensions defined in this document can be advertised via
BGP-LS [RFC7752] using existing BGP-LS TLVs.
The ELC Flag included in the OSPFv2 Extended Prefix TLV and the
OSPFv3 PrefixOptions, as defined in Section 3, is advertised using
the Prefix Attribute Flags TLV (TLV 1170) of the BGP-LS IPv4/IPv6
Prefix NLRI Attribute as defined in section 2.3.2 of
[I-D.ietf-idr-bgp-ls-segment-routing-ext].
The ERLD MSD-type introduced for OSPF in Section 4 is advertised
using the Node MSD TLV (TLV 266) of the BGP-LS Node NLRI Attribute as
defined in section 3 of [I-D.ietf-idr-bgp-ls-segment-routing-ext].
7. IANA Considerations
This document requests IANA to allocate one flag from the OSPFv2
Extended Prefix TLV Flags registry: Extended Prefix TLV Flags registry:
0x20 - E-Flag (ELC Flag) 0x20 - E-Flag (ELC Flag)
This document requests IANA to allocate one bit from the OSPFv3 This document requests IANA to allocate one flag from the OSPFv3
Prefix Options registry: Prefix Options registry:
0x04 - E-Flag (ELC Flag) 0x04 - E-Flag (ELC Flag)
7. Security Considerations 8. Security Considerations
The security considerations as described in [RFC7770] is applicable The security considerations as described in [RFC7770] and
to this document. This document does not introduce any new security [I-D.ietf-mpls-spring-entropy-label] are applicable to this document.
risk.
8. References Incorrectly setting the E flag (ELC capable) (during origination,
inter-area advertisement or redistribution) may lead to black-holing
of the traffic on the egress node.
8.1. Normative References 9. References
9.1. Normative References
[I-D.ietf-idr-bgp-ls-segment-routing-ext]
Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
and M. Chen, "BGP Link-State extensions for Segment
Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
(work in progress), June 2019.
[I-D.ietf-isis-mpls-elc] [I-D.ietf-isis-mpls-elc]
Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. Xu, X., Kini, S., Psenak, P., Filsfils, C., and S.
Litkowski, "Signaling Entropy Label Capability and Entropy Litkowski, "Signaling Entropy Label Capability and Entropy
Readable Label Depth Using IS-IS", draft-ietf-isis-mpls- Readable Label Depth Using IS-IS", draft-ietf-isis-mpls-
elc-06 (work in progress), September 2018. elc-07 (work in progress), May 2019.
[I-D.ietf-isis-segment-routing-msd] [I-D.ietf-isis-segment-routing-msd]
Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
"Signaling MSD (Maximum SID Depth) using IS-IS", draft- "Signaling MSD (Maximum SID Depth) using IS-IS", draft-
ietf-isis-segment-routing-msd-19 (work in progress), ietf-isis-segment-routing-msd-19 (work in progress),
October 2018. October 2018.
[I-D.ietf-ospf-segment-routing-extensions] [I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
skipping to change at page 5, line 46 skipping to change at page 6, line 28
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-22 data plane", draft-ietf-spring-segment-routing-mpls-22
(work in progress), May 2019. (work in progress), May 2019.
[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>.
[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>.
[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>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding", L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012, RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>. <https://www.rfc-editor.org/info/rfc6790>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>. 2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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>.
8.2. Informative References 9.2. Informative References
[I-D.ietf-mpls-spring-entropy-label] [I-D.ietf-mpls-spring-entropy-label]
Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy label for SPRING Shakir, R., and J. Tantsura, "Entropy label for SPRING
tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in
progress), July 2018. progress), July 2018.
Authors' Addresses Authors' Addresses
Xiaohu Xu Xiaohu Xu
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