| < draft-zzhang-rift-sr-01.txt | draft-zzhang-rift-sr-02.txt > | |||
|---|---|---|---|---|
| RIFT Z. Zhang | RIFT Z. Zhang | |||
| Internet-Draft Juniper Networks | Internet-Draft Juniper Networks | |||
| Intended status: Standards Track J. Tantsura | Intended status: Standards Track J. Tantsura | |||
| Expires: October 27, 2019 Apstra, Inc | Expires: May 7, 2020 Apstra, Inc | |||
| D. Fedyk | D. Fedyk | |||
| Individual | Individual | |||
| April 25, 2019 | November 4, 2019 | |||
| SRIFT: Segment Routing In Fat Trees | SRIFT: Segment Routing In Fat Trees | |||
| draft-zzhang-rift-sr-01 | draft-zzhang-rift-sr-02 | |||
| Abstract | Abstract | |||
| This document specifies signaling procedures for Segment Routing | This document specifies signaling procedures for Segment Routing | |||
| [RFC8402] with RIFT. Each node's loopback address, Segment Routing | [RFC8402] with RIFT. Each node's loopback address, Segment Routing | |||
| Global Block (SRGB) and Node Segment Identifier (SID), which must be | Global Block (SRGB) and Node Segment Identifier (SID), which must be | |||
| unique within the SR domain and are typically assigned by SR | unique within the SR domain and are typically assigned by SR | |||
| controllers or management, are distributed southbound from the Top Of | controllers or management, are distributed southbound from the Top Of | |||
| Fabric (TOF) nodes via the Key-Value distribution mechanism, so that | Fabric (TOF) nodes via the Key-Value distribution mechanism, so that | |||
| each node can compute how to reach a node represented by the topmost | each node can compute how to reach a node represented by the topmost | |||
| skipping to change at page 1, line 49 ¶ | skipping to change at page 1, line 49 ¶ | |||
| 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 27, 2019. | This Internet-Draft will expire on May 7, 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 | |||
| 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. Specifications . . . . . . . . . . . . . . . . . . . . . . . 5 | 2. Specifications . . . . . . . . . . . . . . . . . . . . . . . 5 | |||
| 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 | 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 | |||
| 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 | 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 | |||
| 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 | 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 | |||
| 5.1. Normative References . . . . . . . . . . . . . . . . . . 5 | 5.1. Normative References . . . . . . . . . . . . . . . . . . 6 | |||
| 5.2. Informative References . . . . . . . . . . . . . . . . . 6 | 5.2. Informative References . . . . . . . . . . . . . . . . . 6 | |||
| Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 | |||
| 1. Introduction | 1. Introduction | |||
| Before we discuss the SR procedures for RIFT, let us first review how | Before we discuss the SR procedures for RIFT, let us first review how | |||
| SR works with OSPF/ISIS [I-D.ietf-ospf-segment-routing-extensions] | SR works with OSPF/ISIS [I-D.ietf-ospf-segment-routing-extensions] | |||
| [I-D.ietf-isis-segment-routing-extensions]. | [I-D.ietf-isis-segment-routing-extensions]. | |||
| Each node is provisioned with a loopback address, an SRGB, and a Node | Each node is provisioned with a loopback address, an SRGB, and a Node | |||
| skipping to change at page 4, line 38 ¶ | skipping to change at page 4, line 38 ¶ | |||
| With ISIS/OSPF, each node's SRGB is actually flooded everywhere for | With ISIS/OSPF, each node's SRGB is actually flooded everywhere for | |||
| simplicity. With RIFT, North TIEs are flooded all the way north but | simplicity. With RIFT, North TIEs are flooded all the way north but | |||
| South TIEs are only flooded one hop south (and then reflected one hop | South TIEs are only flooded one hop south (and then reflected one hop | |||
| north). While the Node TIEs could be used to flood SRGBs, each node | north). While the Node TIEs could be used to flood SRGBs, each node | |||
| would need to learn its own SRGB first. With RIFT ZTP, the TOF nodes | would need to learn its own SRGB first. With RIFT ZTP, the TOF nodes | |||
| learn the SRGB and Node SID provisioning for every node (from SR | learn the SRGB and Node SID provisioning for every node (from SR | |||
| controllers) and flood them southbound via K-V distribution - there | controllers) and flood them southbound via K-V distribution - there | |||
| is no need to flood SRGB via Node TIEs any more.. | is no need to flood SRGB via Node TIEs any more.. | |||
| For the purpose of SR-TE, a label stack is used - each entry in the | With ISIS/OSPF, a node steer packets in two ways. One is using | |||
| stack represents a node on the TE path towards the destination. | Prefix SIDs - following shortest paths calculated by local SPFs. | |||
| Because RIFT's principal is not to keep specific routes on a node to | ||||
| all destinations that are not south of the node, using Prefix SIDs is | ||||
| not applicable to RIFT, as it does not provide any SR benefit. | ||||
| The other is using SR-TE - following explicit paths specified in a | ||||
| segment list in the packet header. In case of SR-TE with MPLS, a | ||||
| label stack is used - each entry in the stack represents a node on | ||||
| the TE path towards the destination. This can be used for RIFT, as | ||||
| long as controllers provide SR policies to leaf nodes to steer | ||||
| traffic. Leaf nodes themselves won't be able to calculate explicit | ||||
| paths as they don't have the full topology. . | ||||
| Consider the following 4-level topology: | Consider the following 4-level topology: | |||
| TOF1 TOF2 | TOF1 TOF2 | |||
| Spine1_11 Spine1_21 Spine1_21 Spine1_22 | Spine1_11 Spine1_21 Spine1_21 Spine1_22 | |||
| Spine2_11 Spine2_21 Spine2_21 Spine2_22 | Spine2_11 Spine2_21 Spine2_21 Spine2_22 | |||
| Leaf11 Leaf12 Leaf21 Leaf22 | Leaf11 Leaf12 Leaf21 Leaf22 | |||
| skipping to change at page 5, line 48 ¶ | skipping to change at page 6, line 15 ¶ | |||
| 4. Acknowledgements | 4. Acknowledgements | |||
| The authors thank Bruno Rijsman and Antoni Przygenda for their review | The authors thank Bruno Rijsman and Antoni Przygenda for their review | |||
| and suggestions. | and suggestions. | |||
| 5. References | 5. References | |||
| 5.1. Normative References | 5.1. Normative References | |||
| [I-D.ietf-rift-rift] | [I-D.ietf-rift-rift] | |||
| Team, T., "RIFT: Routing in Fat Trees", draft-ietf-rift- | Przygienda, T., Sharma, A., Thubert, P., and D. Afanasiev, | |||
| rift-05 (work in progress), April 2019. | "RIFT: Routing in Fat Trees", draft-ietf-rift-rift-08 | |||
| (work in progress), September 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>. | |||
| 5.2. Informative References | 5.2. Informative References | |||
| [I-D.ietf-isis-segment-routing-extensions] | [I-D.ietf-isis-segment-routing-extensions] | |||
| Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., | Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., | |||
| Gredler, H., and B. Decraene, "IS-IS Extensions for | Gredler, H., and B. Decraene, "IS-IS Extensions for | |||
| Segment Routing", draft-ietf-isis-segment-routing- | Segment Routing", draft-ietf-isis-segment-routing- | |||
| extensions-24 (work in progress), April 2019. | extensions-25 (work in progress), May 2019. | |||
| [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 | |||
| Extensions for Segment Routing", draft-ietf-ospf-segment- | Extensions for Segment Routing", draft-ietf-ospf-segment- | |||
| routing-extensions-27 (work in progress), December 2018. | routing-extensions-27 (work in progress), December 2018. | |||
| [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., | [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., | |||
| Decraene, B., Litkowski, S., and R. Shakir, "Segment | Decraene, B., Litkowski, S., and R. Shakir, "Segment | |||
| Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, | Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, | |||
| End of changes. 8 change blocks. | ||||
| 12 lines changed or deleted | 25 lines changed or added | |||
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