rfc9088.original   rfc9088.txt 
LSR Working Group X. Xu Internet Engineering Task Force (IETF) X. Xu
Internet-Draft Alibaba Inc Request for Comments: 9088 Capitalonline
Intended status: Standards Track S. Kini Category: Standards Track S. Kini
Expires: November 29, 2020 ISSN: 2070-1721
P. Psenak P. Psenak
C. Filsfils C. Filsfils
S. Litkowski S. Litkowski
Cisco Systems, Inc. Cisco Systems, Inc.
M. Bocci M. Bocci
Nokia Nokia
May 28, 2020 August 2021
Signaling Entropy Label Capability and Entropy Readable Label Depth Signaling Entropy Label Capability and Entropy Readable Label Depth
Using IS-IS Using IS-IS
draft-ietf-isis-mpls-elc-13
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 LSP. In addition, it as the Entropy Label Capability (ELC), on that LSP. In addition, 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
IS-IS and BGP-LS. IS-IS and Border Gateway Protocol - Link State (BGP-LS).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on November 29, 2020. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9088.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2021 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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology
3. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3 3. Advertising ELC Using IS-IS
4. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 4 4. Advertising ERLD Using IS-IS
5. Signaling ELC and ERLD in BGP-LS . . . . . . . . . . . . . . 4 5. Signaling ELC and ERLD in BGP-LS
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5 8. References
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 6 Acknowledgements
10.2. Informative References . . . . . . . . . . . . . . . . . 7 Contributors
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses
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 IS-IS [RFC8667]. This state Interior Gateway Protocols (IGP) such as IS-IS [RFC8667]. This
draft defines a mechanism to signal the ELC using IS-IS. document defines a mechanism to signal the ELC using IS-IS.
In cases where Segment Routing (SR) is used with the MPLS Data Plane In cases where Segment Routing (SR) is used with the MPLS data plane
(e.g., SR-MPLS [RFC8660]), it would be useful for ingress LSRs to (e.g., SR-MPLS [RFC8660]), it would be useful for ingress LSRs to
know each intermediate LSR's capability of reading the maximum label know each intermediate LSR's capability of reading the maximum label
stack depth and performing EL-based load-balancing. This capability, stack depth and performing EL-based load-balancing. This capability,
referred to as Entropy Readable Label Depth (ERLD) as defined in referred to as Entropy Readable Label Depth (ERLD) as defined in
[RFC8662], may be used by ingress LSRs to determine the position of [RFC8662], may be used by ingress LSRs to determine the position of
the EL label in the stack, and whether it's necessary to insert the EL label in the stack, and whether it's necessary to insert
multiple ELs at different positions in the label stack. This multiple ELs at different positions in the label stack. This
document defines a mechanism to signal the ERLD using IS-IS. document defines a mechanism to signal the ERLD using IS-IS.
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
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Advertising ELC Using IS-IS 3. Advertising ELC Using IS-IS
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 a prefix. In a advantageous to associate and advertise the ELC with a prefix. In a
multi-area network, routers may not know the identity of the prefix multi-area network, routers may not know the identity of the prefix
originator in a remote area, or may not know the capabilities of such originator in a remote area or may not know the capabilities of such
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.
Bit 3 in the Prefix Attribute Flags [RFC7794] is used as the ELC Flag Bit 3 in the Prefix Attribute Flags [RFC7794] is used as the ELC Flag
(E-flag), as shown in Figure 1. If a router has multiple interfaces, (E-Flag), as shown in Figure 1. If a router has multiple interfaces,
the router MUST NOT announce the ELC for any local host prefixes the router MUST NOT announce the ELC for any local host prefixes
unless all of its interfaces are capable of processing ELs. If a unless all of its interfaces are capable of processing ELs. If a
router supports ELs on all of its interfaces, it SHOULD set the ELC router supports ELs on all of its interfaces, it SHOULD set the ELC
for every local host prefix it advertises in IS-IS. for every local host prefix it advertises in IS-IS.
0 1 2 3 4 5 6 7... 0 1 2 3 4 5 6 7...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
|X|R|N|E| ... |X|R|N|E| ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
Figure 1: Prefix Attribute Flags
E-flag: ELC Flag (Bit 3) - Set for local host prefix of the Figure 1: Prefix Attribute Flags
originating node if it supports ELC on all interfaces.
E-Flag:
ELC Flag (Bit 3) - Set for local host prefix of the originating
node if it supports ELC on all interfaces.
The ELC signaling MUST be preserved when a router propagates a prefix The ELC signaling MUST be preserved when a router propagates a prefix
between ISIS levels [RFC5302]. between IS-IS levels [RFC5302].
When redistributing a prefix between two IS-IS protocol instances or When redistributing a prefix between two IS-IS protocol instances or
redistributing from another protocol to an IS-IS protocol instance, a redistributing from another protocol to an IS-IS protocol instance, a
router SHOULD preserve the ELC signaling for that prefix if it router SHOULD preserve the ELC signaling for that prefix if it
exists. The exact mechanism used to exchange ELC between protocol exists. The exact mechanism used to exchange ELC between protocol
instances running on an Autonomous System Boundary Router is outside instances running on an Autonomous System Border Router is outside of
of the scope of this document. the scope of this document.
4. Advertising ERLD Using IS-IS 4. Advertising ERLD Using IS-IS
A new MSD-Type [RFC8491], called ERLD-MSD, is defined to advertise A new MSD-Type [RFC8491], called ERLD-MSD, is defined to advertise
the ERLD [RFC8662] of a given router. A MSD-Type code 2 has been the ERLD [RFC8662] of a given router. An MSD-Type code 2 has been
assigned by IANA for ERLD-MSD. The MSD-Value field is set to the assigned by IANA for ERLD-MSD. The MSD-Value field is set to the
ERLD in the range between 0 to 255. The scope of the advertisement ERLD in the range between 0 to 255. The scope of the advertisement
depends on the application. If a router has multiple interfaces with depends on the application. If a router has multiple interfaces with
different capabilities of reading the maximum label stack depth, the different capabilities of reading the maximum label stack depth, the
router MUST advertise the smallest value found across all its router MUST advertise the smallest value found across all its
interfaces. 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.
The considerations for advertising the ERLD are specified in The considerations for advertising the ERLD are specified in
[RFC8662]. [RFC8662].
If the ERLD-MSD Type is received in the Link MSD Sub-TLV, it MUST be If the ERLD-MSD type is received in the Link MSD sub-TLV, it MUST be
ignored. ignored.
5. Signaling ELC and ERLD in BGP-LS 5. Signaling ELC and ERLD in BGP-LS
The IS-IS extensions defined in this document can be advertised via The IS-IS extensions defined in this document can be advertised via
BGP-LS (Distribution of Link-State and TE Information Using BGP) BGP-LS (distribution of Link-State and TE information using BGP)
[RFC7752] using existing BGP-LS TLVs. [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 [RFC9085].
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]. [RFC8814].
6. IANA Considerations 6. IANA Considerations
Early allocation has been done by IANA for this document as follows: IANA has completed the following actions for this document:
- Bit 3 in the Bit Values for Prefix Attribute Flags Sub-TLV * Bit 3 in the "Bit Values for Prefix Attribute Flags Sub-TLV"
registry has been assigned to the ELC Flag. IANA is asked to registry has been assigned to the ELC Flag. IANA has updated the
update the registry to reflect the name used in this document: ELC registry to reflect the name used in this document: ELC Flag
Flag (E-flag). (E-Flag).
- Type 2 in the IGP MSD-Types registry has been assigned for the * Type 2 in the "IGP MSD-Types" registry has been assigned for the
ERLD-MSD. IANA is asked to update the registry to reflect the ERLD-MSD. IANA has updated the registry to reflect the name used
name used in this document: ERLD-MSD. in this document: ERLD-MSD.
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 IS-IS and BGP-LS. As such, the security capabilities using IS-IS and BGP-LS. As such, the security
considerations as described in [RFC7981], [RFC7752], [RFC7794], considerations as described in [RFC7752], [RFC7794], [RFC7981],
[RFC8491], [RFC8662], [I-D.ietf-idr-bgp-ls-segment-routing-ext] and [RFC8491], [RFC8662], [RFC8814], and [RFC9085] 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 poor or no load-balancing of the MPLS redistribution may lead to poor or no load-balancing of the MPLS
traffic or black-holing of the MPLS traffic on the egress node. traffic or to MPLS traffic being discarded on the egress node.
Incorrectly setting of the ERLD value may lead to poor or no load- Incorrectly setting the ERLD value may lead to poor or no load-
balancing of the MPLS traffic. balancing of the MPLS traffic.
8. Contributors 8. References
The following people contributed to the content of this document and
should be considered as co-authors:
Gunter Van de Velde (editor)
Nokia
Antwerp
BE
Email: gunter.van_de_velde@nokia.com
Wim Henderickx
Nokia
Belgium
Email: wim.henderickx@nokia.com
Keyur Patel
Arrcus
USA
Email: keyur@arrcus.com
9. Acknowledgements
The authors would like to thank Yimin Shen, George Swallow, Acee
Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno Decraene
Carlos Pignataro, Wim Hendrickx, and Gunter Van De Velde for their
valuable comments.
10. References
10.1. 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-idr-bgp-ls-segment-routing-msd] 8.1. Normative References
Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G.,
and N. Triantafillis, "Signaling MSD (Maximum SID Depth)
using Border Gateway Protocol - Link State", draft-ietf-
idr-bgp-ls-segment-routing-msd-18 (work in progress), May
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>.
[RFC5302] Li, T., Smit, H., and T. Przygienda, "Domain-Wide Prefix [RFC5302] Li, T., Smit, H., and T. Przygienda, "Domain-Wide Prefix
Distribution with Two-Level IS-IS", RFC 5302, Distribution with Two-Level IS-IS", RFC 5302,
DOI 10.17487/RFC5302, October 2008, DOI 10.17487/RFC5302, October 2008,
<https://www.rfc-editor.org/info/rfc5302>. <https://www.rfc-editor.org/info/rfc5302>.
skipping to change at page 7, line 30 skipping to change at line 254
"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
DOI 10.17487/RFC8491, November 2018, DOI 10.17487/RFC8491, November 2018,
<https://www.rfc-editor.org/info/rfc8491>. <https://www.rfc-editor.org/info/rfc8491>.
[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>.
10.2. Informative References [RFC8814] Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G.,
and N. Triantafillis, "Signaling Maximum SID Depth (MSD)
Using the Border Gateway Protocol - Link State", RFC 8814,
DOI 10.17487/RFC8814, August 2020,
<https://www.rfc-editor.org/info/rfc8814>.
[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085,
DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
8.2. Informative References
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660, Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019, DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>. <https://www.rfc-editor.org/info/rfc8660>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667, Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019, DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>. <https://www.rfc-editor.org/info/rfc8667>.
Acknowledgements
The authors would like to thank Yimin Shen, George Swallow, Acee
Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno
Decraene, Carlos Pignataro, Wim Hendrickx, and Gunter Van de Velde
for their valuable comments.
Contributors
The following people contributed to the content of this document and
should be considered as coauthors:
Gunter Van de Velde (editor)
Nokia
Antwerp
Belgium
Email: gunter.van_de_velde@nokia.com
Wim Henderickx
Nokia
Belgium
Email: wim.henderickx@nokia.com
Keyur Patel
Arrcus
United States of America
Email: keyur@arrcus.com
Authors' Addresses Authors' Addresses
Xiaohu Xu Xiaohu Xu
Alibaba Inc Capitalonline
Email: xiaohu.xu@capitalonline.net
Email: xiaohu.xxh@alibaba-inc.com
Sriganesh Kini Sriganesh Kini
Email: sriganeshkini@gmail.com Email: sriganeshkini@gmail.com
Peter Psenak Peter Psenak
Cisco Systems, Inc. Cisco Systems, Inc.
Eurovea Centre, Central 3 Eurovea Centre, Central 3
Pribinova Street 10 Pribinova Street 10
Bratislava 81109 81109 Bratislava
Slovakia Slovakia
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
Clarence Filsfils Clarence Filsfils
Cisco Systems, Inc. Cisco Systems, Inc.
Brussels Brussels
Belgium Belgium
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
skipping to change at page 8, line 34 skipping to change at line 348
Stephane Litkowski Stephane Litkowski
Cisco Systems, Inc. Cisco Systems, Inc.
La Rigourdiere La Rigourdiere
Cesson Sevigne Cesson Sevigne
France France
Email: slitkows@cisco.com Email: slitkows@cisco.com
Matthew Bocci Matthew Bocci
Nokia Nokia
Shoppenhangers Road 740 Waterside Drive
Maidenhead, Berks Aztec West Business Park
UK Bristol
BS32 4UF
United Kingdom
Email: matthew.bocci@nokia.com Email: matthew.bocci@nokia.com
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