draft-ietf-lsr-flex-algo-12.txt   draft-ietf-lsr-flex-algo-13.txt 
Network Working Group P. Psenak, Ed. Network Working Group P. Psenak, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track S. Hegde Intended status: Standards Track S. Hegde
Expires: April 10, 2021 Juniper Networks, Inc. Expires: April 25, 2021 Juniper Networks, Inc.
C. Filsfils C. Filsfils
K. Talaulikar K. Talaulikar
Cisco Systems, Inc. Cisco Systems, Inc.
A. Gulko A. Gulko
Individual Individual
October 7, 2020 October 22, 2020
IGP Flexible Algorithm IGP Flexible Algorithm
draft-ietf-lsr-flex-algo-12 draft-ietf-lsr-flex-algo-13
Abstract Abstract
IGP protocols traditionally compute best paths over the network based IGP protocols traditionally compute best paths over the network based
on the IGP metric assigned to the links. Many network deployments on the IGP metric assigned to the links. Many network deployments
use RSVP-TE based or Segment Routing based Traffic Engineering to use RSVP-TE based or Segment Routing based Traffic Engineering to
steer traffic over a path that is computed using different metrics or steer traffic over a path that is computed using different metrics or
constraints than the shortest IGP path. This document proposes a constraints than the shortest IGP path. This document proposes a
solution that allows IGPs themselves to compute constraint-based solution that allows IGPs themselves to compute constraint-based
paths over the network. This document also specifies a way of using paths over the network. This document also specifies a way of using
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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 April 10, 2021. This Internet-Draft will expire on April 25, 2021.
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
(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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14.2. Usage of SRLG Exclude Rule with Flex-Algorithm . . . . . 26 14.2. Usage of SRLG Exclude Rule with Flex-Algorithm . . . . . 26
14.3. Max-metric consideration . . . . . . . . . . . . . . . . 26 14.3. Max-metric consideration . . . . . . . . . . . . . . . . 26
15. Backward Compatibility . . . . . . . . . . . . . . . . . . . 27 15. Backward Compatibility . . . . . . . . . . . . . . . . . . . 27
16. Security Considerations . . . . . . . . . . . . . . . . . . . 27 16. Security Considerations . . . . . . . . . . . . . . . . . . . 27
17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
17.1. IGP IANA Considerations . . . . . . . . . . . . . . . . 27 17.1. IGP IANA Considerations . . . . . . . . . . . . . . . . 27
17.1.1. IGP Algorithm Types Registry . . . . . . . . . . . . 27 17.1.1. IGP Algorithm Types Registry . . . . . . . . . . . . 27
17.1.2. IGP Metric-Type Registry . . . . . . . . . . . . . . 27 17.1.2. IGP Metric-Type Registry . . . . . . . . . . . . . . 27
17.2. Flexible Algorithm Definition Flags Registry . . . . . . 28 17.2. Flexible Algorithm Definition Flags Registry . . . . . . 28
17.3. ISIS IANA Considerations . . . . . . . . . . . . . . . . 28 17.3. ISIS IANA Considerations . . . . . . . . . . . . . . . . 28
17.3.1. Sub TLVs for Type 242 . . . . . . . . . . . . . . . 28 17.3.1. Sub TLVs for Type 242 . . . . . . . . . . . . . . . 29
17.3.2. Sub TLVs for for TLVs 135, 235, 236, and 237 . . . . 29 17.3.2. Sub TLVs for for TLVs 135, 235, 236, and 237 . . . . 29
17.3.3. Sub-Sub-TLVs for Flexible Algorithm Definition Sub- 17.3.3. Sub-Sub-TLVs for Flexible Algorithm Definition Sub-
TLV . . . . . . . . . . . . . . . . . . . . . . . . 29 TLV . . . . . . . . . . . . . . . . . . . . . . . . 29
17.4. OSPF IANA Considerations . . . . . . . . . . . . . . . . 30 17.4. OSPF IANA Considerations . . . . . . . . . . . . . . . . 30
17.4.1. OSPF Router Information (RI) TLVs Registry . . . . . 30 17.4.1. OSPF Router Information (RI) TLVs Registry . . . . . 30
17.4.2. OSPFv2 Extended Prefix TLV Sub-TLVs . . . . . . . . 30 17.4.2. OSPFv2 Extended Prefix TLV Sub-TLVs . . . . . . . . 30
17.4.3. OSPFv3 Extended-LSA Sub-TLVs . . . . . . . . . . . . 30 17.4.3. OSPFv3 Extended-LSA Sub-TLVs . . . . . . . . . . . . 30
17.4.4. OSPF Flexible Algorithm Definition TLV Sub-TLV 17.4.4. OSPF Flexible Algorithm Definition TLV Sub-TLV
Registry . . . . . . . . . . . . . . . . . . . . . . 31 Registry . . . . . . . . . . . . . . . . . . . . . . 31
17.4.5. Link Attribute Applications Registry . . . . . . . . 32 17.4.5. Link Attribute Applications Registry . . . . . . . . 32
18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32 18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
19. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
19.1. Normative References . . . . . . . . . . . . . . . . . . 32 19.1. Normative References . . . . . . . . . . . . . . . . . . 32
19.2. Informative References . . . . . . . . . . . . . . . . . 34 19.2. Informative References . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction 1. Introduction
An IGP-computed path based on the shortest IGP metric must often be An IGP-computed path based on the shortest IGP metric is often be
replaced by a traffic-engineered path due to the traffic requirements replaced by a traffic-engineered path due to the traffic requirements
which are not reflected by the IGP metric. Some networks engineer which are not reflected by the IGP metric. Some networks engineer
the IGP metric assignments in a way that the IGP metric reflects the the IGP metric assignments in a way that the IGP metric reflects the
link bandwidth or delay. If, for example, the IGP metric is link bandwidth or delay. If, for example, the IGP metric is
reflecting the bandwidth on the link and the application traffic is reflecting the bandwidth on the link and the application traffic is
delay sensitive, the best IGP path may not reflect the best path from delay sensitive, the best IGP path may not reflect the best path from
such an application's perspective. such an application's perspective.
To overcome this limitation, various sorts of traffic engineering To overcome this limitation, various sorts of traffic engineering
have been deployed, including RSVP-TE and SR-TE, in which case the TE have been deployed, including RSVP-TE and SR-TE, in which case the TE
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The link can be made un-reachable for all Flex-Algorithms that use TE The link can be made un-reachable for all Flex-Algorithms that use TE
metric, as described in Section 5.1, by removing the Flex-Algorithm metric, as described in Section 5.1, by removing the Flex-Algorithm
ASLA TE metric advertisement for the link. The link can be made the ASLA TE metric advertisement for the link. The link can be made the
link of last resort by setting the TE metric value in the Flex- link of last resort by setting the TE metric value in the Flex-
Algorithm ASLA delay advertisement for the link to the value of (2^24 Algorithm ASLA delay advertisement for the link to the value of (2^24
- 1) in ISIS and (2^32 - 1) in OSPF. - 1) in ISIS and (2^32 - 1) in OSPF.
15. Backward Compatibility 15. Backward Compatibility
This extension brings no new backward compatibility issues. This extension brings no new backward compatibility issues. ISIS,
OSPFv2 and OSPFv3 all have well defined handling of unrecognized TLVs
and sub-TLVs that allows the introduction of the new extensions,
similar to those defined here, without introducing any
interoperability issues.
16. Security Considerations 16. Security Considerations
This draft adds two new ways to disrupt IGP networks: This draft adds two new ways to disrupt IGP networks:
An attacker can hijack a particular Flex-Algorithm by advertising An attacker can hijack a particular Flex-Algorithm by advertising
a FAD with a priority of 255 (or any priority higher than that of a FAD with a priority of 255 (or any priority higher than that of
the legitimate nodes). the legitimate nodes).
An attacker could make it look like a router supports a particular An attacker could make it look like a router supports a particular
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Type: 128-255. Type: 128-255.
Description: Flexible Algorithms. Description: Flexible Algorithms.
Reference: This document (Section 4). Reference: This document (Section 4).
17.1.2. IGP Metric-Type Registry 17.1.2. IGP Metric-Type Registry
IANA is requested to set up a registry called "IGP Metric-Type IANA is requested to set up a registry called "IGP Metric-Type
Registry" under a "Interior Gateway Protocol (IGP) Parameters" IANA Registry" under an "Interior Gateway Protocol (IGP) Parameters" IANA
registries. The registration policy for this registry is "Standards registries. The registration policy for this registry is "Standards
Action" ([RFC8126] and [RFC7120]). Action" ([RFC8126] and [RFC7120]).
Values in this registry come from the range 0-255. Values in this registry come from the range 0-255.
This document registers following values in the "IGP Metric-Type This document registers following values in the "IGP Metric-Type
Registry": Registry":
Type: 0 Type: 0
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Description: Traffic Engineering Default Metric as defined in Description: Traffic Engineering Default Metric as defined in
[RFC5305], section 3.7, and Traffic engineering metric as defined [RFC5305], section 3.7, and Traffic engineering metric as defined
in [RFC3630], section 2.5.5 in [RFC3630], section 2.5.5
Reference: This document (Section 5.1) Reference: This document (Section 5.1)
17.2. Flexible Algorithm Definition Flags Registry 17.2. Flexible Algorithm Definition Flags Registry
IANA is requested to set up a registry called "ISIS Flexible IANA is requested to set up a registry called "ISIS Flexible
Algorithm Definition Flags Registry" under a "Interior Gateway Algorithm Definition Flags Registry" under an "Interior Gateway
Protocol (IGP) Parameters" IANA registries. The registration policy Protocol (IGP) Parameters" IANA registries. The registration policy
for this registry is "Standards Action" ([RFC8126] and [RFC7120]). for this registry is "Standards Action" ([RFC8126] and [RFC7120]).
This document defines the following single bit in Flexible Algorithm This document defines the following single bit in Flexible Algorithm
Definition Flags registry: Definition Flags registry:
Bit # Name Bit # Name
----- ------------------------------ ----- ------------------------------
0 Prefix Metric Flag (M-flag) 0 Prefix Metric Flag (M-flag)
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Levels", <https://tools.ietf.org/html/bcp14>. Levels", <https://tools.ietf.org/html/bcp14>.
[I-D.ietf-isis-te-app] [I-D.ietf-isis-te-app]
Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS Application-Specific Link Attributes", J. Drake, "IS-IS Application-Specific Link Attributes",
draft-ietf-isis-te-app-19 (work in progress), June 2020. draft-ietf-isis-te-app-19 (work in progress), June 2020.
[I-D.ietf-lsr-isis-srv6-extensions] [I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extension to Support Segment Routing over Z. Hu, "IS-IS Extension to Support Segment Routing over
IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-10 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-11
(work in progress), September 2020. (work in progress), October 2020.
[I-D.ietf-lsr-ospfv3-srv6-extensions] [I-D.ietf-lsr-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak, Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
"OSPFv3 Extensions for SRv6", draft-ietf-lsr- "OSPFv3 Extensions for SRv6", draft-ietf-lsr-
ospfv3-srv6-extensions-01 (work in progress), August 2020. ospfv3-srv6-extensions-01 (work in progress), August 2020.
[I-D.ietf-ospf-te-link-attr-reuse] [I-D.ietf-ospf-te-link-attr-reuse]
Psenak, P., Ginsberg, L., Henderickx, W., Tantsura, J., Psenak, P., Ginsberg, L., Henderickx, W., Tantsura, J.,
and J. Drake, "OSPF Application-Specific Link Attributes", and J. Drake, "OSPF Application-Specific Link Attributes",
draft-ietf-ospf-te-link-attr-reuse-16 (work in progress), draft-ietf-ospf-te-link-attr-reuse-16 (work in progress),
 End of changes. 11 change blocks. 
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