| draft-ietf-idr-bgp-prefix-sid-24.txt | draft-ietf-idr-bgp-prefix-sid-25.txt | |||
|---|---|---|---|---|
| IDR S. Previdi, Ed. | IDR S. Previdi | |||
| Internet-Draft C. Filsfils | Internet-Draft C. Filsfils | |||
| Intended status: Standards Track A. Lindem, Ed. | Intended status: Standards Track A. Lindem, Ed. | |||
| Expires: December 16, 2018 Cisco Systems | Expires: December 17, 2018 Cisco Systems | |||
| A. Sreekantiah | A. Sreekantiah | |||
| H. Gredler | H. Gredler | |||
| RtBrick Inc. | RtBrick Inc. | |||
| June 14, 2018 | June 15, 2018 | |||
| Segment Routing Prefix SID extensions for BGP | Segment Routing Prefix SID extensions for BGP | |||
| draft-ietf-idr-bgp-prefix-sid-24 | draft-ietf-idr-bgp-prefix-sid-25 | |||
| Abstract | Abstract | |||
| The Segment Routing (SR) architecture allows a node to steer a packet | The Segment Routing (SR) architecture allows a node to steer a packet | |||
| flow through any topological path and service chain by leveraging | flow through any topological path and service chain by leveraging | |||
| source routing. The ingress node prepends an SR header to a packet | source routing. The ingress node prepends an SR header to a packet | |||
| containing a set of segment identifiers (SID). Each SID represents a | containing a set of segment identifiers (SID). Each SID represents a | |||
| topological or a service-based instruction. Per-flow state is | topological or a service-based instruction. Per-flow state is | |||
| maintained only on the ingress node of the SR domain. An SR domain | maintained only on the ingress node of the SR domain. An SR domain | |||
| is defined as a single administrative domain for global SID | is defined as a single administrative domain for global SID | |||
| assignment. | assignment. | |||
| This document defines an optional, transitive BGP attribute for | This document defines an optional, transitive BGP attribute for | |||
| announcing BGP Prefix Segment Identifiers (BGP Prefix-SID) | announcing BGP Prefix Segment Identifiers (BGP Prefix-SID) | |||
| information. | information the specification for SR-MPLS SIDs. | |||
| 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", "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. | |||
| Status of This Memo | Status of This Memo | |||
| skipping to change at page 2, line 10 ¶ | skipping to change at page 2, line 10 ¶ | |||
| 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 http://datatracker.ietf.org/drafts/current/. | Drafts is at http://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 December 16, 2018. | This Internet-Draft will expire on December 17, 2018. | |||
| Copyright Notice | Copyright Notice | |||
| Copyright (c) 2018 IETF Trust and the persons identified as the | Copyright (c) 2018 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 | |||
| (http://trustee.ietf.org/license-info) in effect on the date of | (http://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 | |||
| carefully, as they describe your rights and restrictions with respect | carefully, as they describe your rights and restrictions with respect | |||
| 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 | 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 | |||
| 2. BGP-Prefix-SID . . . . . . . . . . . . . . . . . . . . . . . 4 | 2. MPLS BGP Prefix SID . . . . . . . . . . . . . . . . . . . . . 4 | |||
| 2.1. MPLS BGP Prefix SID . . . . . . . . . . . . . . . . . . . 4 | ||||
| 3. BGP Prefix-SID Attribute . . . . . . . . . . . . . . . . . . 5 | 3. BGP Prefix-SID Attribute . . . . . . . . . . . . . . . . . . 5 | |||
| 3.1. Label-Index TLV . . . . . . . . . . . . . . . . . . . . . 6 | 3.1. Label-Index TLV . . . . . . . . . . . . . . . . . . . . . 6 | |||
| 3.2. Originator SRGB TLV . . . . . . . . . . . . . . . . . . . 6 | 3.2. Originator SRGB TLV . . . . . . . . . . . . . . . . . . . 6 | |||
| 4. Receiving BGP Prefix-SID Attribute . . . . . . . . . . . . . 8 | 4. Receiving BGP Prefix-SID Attribute . . . . . . . . . . . . . 8 | |||
| 4.1. MPLS Dataplane: Labeled Unicast . . . . . . . . . . . . . 8 | 4.1. MPLS Dataplane: Labeled Unicast . . . . . . . . . . . . . 8 | |||
| 5. Advertising BGP Prefix-SID Attribute . . . . . . . . . . . . 9 | 5. Advertising BGP Prefix-SID Attribute . . . . . . . . . . . . 9 | |||
| 5.1. MPLS Dataplane: Labeled Unicast . . . . . . . . . . . . . 10 | 5.1. MPLS Dataplane: Labeled Unicast . . . . . . . . . . . . . 10 | |||
| 6. Error Handling of BGP Prefix-SID Attribute . . . . . . . . . 10 | 6. Error Handling of BGP Prefix-SID Attribute . . . . . . . . . 10 | |||
| 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 | 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 | |||
| 8. Manageability Considerations . . . . . . . . . . . . . . . . 12 | 8. Manageability Considerations . . . . . . . . . . . . . . . . 12 | |||
| 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 | 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 | |||
| 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13 | 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13 | |||
| 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 | 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 | |||
| 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 | 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 | |||
| 12.1. Normative References . . . . . . . . . . . . . . . . . . 14 | 12.1. Normative References . . . . . . . . . . . . . . . . . . 14 | |||
| 12.2. Informative References . . . . . . . . . . . . . . . . . 15 | 12.2. Informative References . . . . . . . . . . . . . . . . . 15 | |||
| Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 | |||
| 1. Introduction | 1. Introduction | |||
| The Segment Routing (SR) architecture leverages the source routing | The Segment Routing (SR) architecture leverages the source routing | |||
| skipping to change at page 4, line 21 ¶ | skipping to change at page 4, line 21 ¶ | |||
| ASes agree on the SID allocation scheme. Alternatively, when | ASes agree on the SID allocation scheme. Alternatively, when | |||
| interconnecting ASes, the ASBRs of each domain will have to handle | interconnecting ASes, the ASBRs of each domain will have to handle | |||
| the advertisement of unique SIDs. The mechanisms for such | the advertisement of unique SIDs. The mechanisms for such | |||
| interconnection are outside the scope of the protocol extensions | interconnection are outside the scope of the protocol extensions | |||
| defined in this document. | defined in this document. | |||
| o A BGP Prefix-SID MAY be attached to a prefix. This implies that | o A BGP Prefix-SID MAY be attached to a prefix. This implies that | |||
| each prefix is advertised individually, reducing the ability to | each prefix is advertised individually, reducing the ability to | |||
| pack BGP advertisements (when sharing common attributes). | pack BGP advertisements (when sharing common attributes). | |||
| 2. BGP-Prefix-SID | 2. MPLS BGP Prefix SID | |||
| The BGP Prefix-SID advertised for BGP prefix P indicates that the | ||||
| segment routed path should be used (as described below) if the BGP | ||||
| best path selects the corresponding Network Layer Reachability | ||||
| Information (NLRI). | ||||
| 2.1. MPLS BGP Prefix SID | ||||
| The BGP Prefix-SID is realized on the MPLS dataplane | The BGP Prefix-SID is realized on the MPLS dataplane | |||
| ([I-D.ietf-spring-segment-routing-mpls]) in the following way: | ([I-D.ietf-spring-segment-routing-mpls]) in the following way: | |||
| The operator assigns a globally unique label index, L_I, to a | The operator assigns a globally unique label index, L_I, to a | |||
| locally originated prefix of a BGP speaker N which is advertised | locally originated prefix of a BGP speaker N which is advertised | |||
| to all other BGP speakers in the SR domain. | to all other BGP speakers in the SR domain. | |||
| According to [I-D.ietf-spring-segment-routing], each BGP speaker | According to [I-D.ietf-spring-segment-routing], each BGP speaker | |||
| is configured with a label block called the Segment Routing Global | is configured with a label block called the Segment Routing Global | |||
| skipping to change at page 5, line 7 ¶ | skipping to change at page 4, line 48 ¶ | |||
| [I-D.ietf-spring-segment-routing-msdc]. | [I-D.ietf-spring-segment-routing-msdc]. | |||
| If traffic-engineering within the SR domain is required, each node | If traffic-engineering within the SR domain is required, each node | |||
| may also be required to advertise topological information and | may also be required to advertise topological information and | |||
| Peering SIDs for each of its links and peers. This information is | Peering SIDs for each of its links and peers. This information is | |||
| required to perform the explicit path computation and to express | required to perform the explicit path computation and to express | |||
| an explicit path as a list of SIDs. The advertisement of | an explicit path as a list of SIDs. The advertisement of | |||
| topological information and peer segments (Peer SIDs) is done | topological information and peer segments (Peer SIDs) is done | |||
| through [I-D.ietf-idr-bgpls-segment-routing-epe]. | through [I-D.ietf-idr-bgpls-segment-routing-epe]. | |||
| If the BGP speakers are not all configured with the same SRGB, and | If a prefix segment is to be included in an MPLS label stack, | |||
| if traffic-engineering within the SR domain is required, each node | e.g., for traffic engineering purposes, the knowledge of the SRGB | |||
| may be required to advertise its local SRGB in addition to the | of the originator of the prefix is required in order to compute | |||
| topological information. | the local label used by the originator. | |||
| This document assumes that BGP-LS is the preferred method for | This document assumes that BGP-LS is the preferred method for | |||
| collecting both peer segments (Peer SIDs) and SRGB information | collecting both peer segments (Peer SIDs) and SRGB information | |||
| through [RFC7752], [I-D.ietf-idr-bgpls-segment-routing-epe], and | through [RFC7752], [I-D.ietf-idr-bgpls-segment-routing-epe], and | |||
| [I-D.ietf-idr-bgp-ls-segment-routing-ext]. However, as an | [I-D.ietf-idr-bgp-ls-segment-routing-ext]. However, as an | |||
| optional alternative for the advertisement of the local SRGB | optional alternative for the advertisement of the local SRGB | |||
| without the topology nor the peer SIDs, hence without | without the topology nor the peer SIDs, hence without | |||
| applicability for TE, the Originator SRGB TLV of the BGP Prefix- | applicability for TE, the Originator SRGB TLV of the BGP Prefix- | |||
| SID attribute is specified in Section 3.2 of this document. | SID attribute is specified in Section 3.2 of this document. | |||
| skipping to change at page 12, line 14 ¶ | skipping to change at page 12, line 14 ¶ | |||
| registration policy for flag bits will Expert Review [RFC8126] | registration policy for flag bits will Expert Review [RFC8126] | |||
| consistent with the BGP Prefix-SID TLV Types registry. | consistent with the BGP Prefix-SID TLV Types registry. | |||
| Finally, this document requests creation of the "BGP Prefix-SID | Finally, this document requests creation of the "BGP Prefix-SID | |||
| Originator SRGB TLV Flags" registry under the "Border Gateway | Originator SRGB TLV Flags" registry under the "Border Gateway | |||
| Protocol (BGP) Parameters" registry, Reference: draft-ietf-idr-bgp- | Protocol (BGP) Parameters" registry, Reference: draft-ietf-idr-bgp- | |||
| prefix-sid. Initially, this 16-bit flags registry will be empty. | prefix-sid. Initially, this 16-bit flags registry will be empty. | |||
| The registration policy for flag bits will Expert Review [RFC8126] | The registration policy for flag bits will Expert Review [RFC8126] | |||
| consistent with the BGP Prefix-SID TLV Types registry. | consistent with the BGP Prefix-SID TLV Types registry. | |||
| The designated experts must be good and faithful stewards of the | ||||
| above registries, assuring that each request is legitimate and | ||||
| corresponds to a viable use case. Given the limited number of bits | ||||
| in the flags registries and the applicability to a single TLV, | ||||
| additional scrutiny should be afforded to flag bit allocation | ||||
| requests. In general, no single use case should require more than | ||||
| one flag bit and, should the use case require more, alternate | ||||
| encodings using new TLVs should be considered. | ||||
| 8. Manageability Considerations | 8. Manageability Considerations | |||
| This document defines a BGP attribute to address use cases such as | This document defines a BGP attribute to address use cases such as | |||
| the one described in [I-D.ietf-spring-segment-routing-msdc]. It is | the one described in [I-D.ietf-spring-segment-routing-msdc]. It is | |||
| assumed that advertisement of the BGP Prefix-SID attribute is | assumed that advertisement of the BGP Prefix-SID attribute is | |||
| controlled by the operator in order to: | controlled by the operator in order to: | |||
| o Prevent undesired origination/advertisement of the BGP Prefix-SID | o Prevent undesired origination/advertisement of the BGP Prefix-SID | |||
| attribute. By default, a BGP Prefix-SID attribute SHOULD NOT be | attribute. By default, a BGP Prefix-SID attribute SHOULD NOT be | |||
| attached to a prefix and advertised. Hence, BGP Prefix-SID | attached to a prefix and advertised. Hence, BGP Prefix-SID | |||
| skipping to change at page 16, line 23 ¶ | skipping to change at page 16, line 41 ¶ | |||
| editor.org/info/rfc5004>. | editor.org/info/rfc5004>. | |||
| [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and | [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and | |||
| S. Ray, "North-Bound Distribution of Link-State and | S. Ray, "North-Bound Distribution of Link-State and | |||
| Traffic Engineering (TE) Information Using BGP", RFC 7752, | Traffic Engineering (TE) Information Using BGP", RFC 7752, | |||
| DOI 10.17487/RFC7752, March 2016, <https://www.rfc- | DOI 10.17487/RFC7752, March 2016, <https://www.rfc- | |||
| editor.org/info/rfc7752>. | editor.org/info/rfc7752>. | |||
| Authors' Addresses | Authors' Addresses | |||
| Stefano Previdi (editor) | Stefano Previdi | |||
| Cisco Systems | Cisco Systems | |||
| IT | IT | |||
| Email: stefano@previdi.net | Email: stefano@previdi.net | |||
| Clarence Filsfils | Clarence Filsfils | |||
| Cisco Systems | Cisco Systems | |||
| Brussels | Brussels | |||
| Belgium | Belgium | |||
| Email: cfilsfils@cisco.com | Email: cfilsfils@cisco.com | |||
| Acee Lindem (editor) | Acee Lindem (editor) | |||
| Cisco Systems | Cisco Systems | |||
| 301 Midenhall Way | 301 Midenhall Way | |||
| End of changes. 13 change blocks. | ||||
| 23 lines changed or deleted | 23 lines changed or added | |||
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