draft-ietf-idr-bgp-prefix-sid-26.txt   draft-ietf-idr-bgp-prefix-sid-27.txt 
IDR S. Previdi 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 23, 2018 Cisco Systems Expires: December 28, 2018 Cisco Systems
A. Sreekantiah A. Sreekantiah
H. Gredler H. Gredler
RtBrick Inc. RtBrick Inc.
June 21, 2018 June 26, 2018
Segment Routing Prefix SID extensions for BGP Segment Routing Prefix SID extensions for BGP
draft-ietf-idr-bgp-prefix-sid-26 draft-ietf-idr-bgp-prefix-sid-27
Abstract Abstract
Segment Routing (SR) leverages the source routing paradigm. A node Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through an ordered list of instructions, called steers a packet through an ordered list of instructions, called
segments. A segment can represent any instruction, topological or segments. A segment can represent any instruction, topological or
service-based. The ingress node prepends an SR header to a packet service-based. 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
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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 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 23, 2018. This Internet-Draft will expire on December 28, 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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. MPLS BGP Prefix SID . . . . . . . . . . . . . . . . . . . . . 4 2. MPLS BGP Prefix SID . . . . . . . . . . . . . . . . . . . . . 4
3. BGP Prefix-SID Attribute . . . . . . . . . . . . . . . . . . 5 3. BGP Prefix-SID Attribute . . . . . . . . . . . . . . . . . . 5
3.1. Label-Index TLV . . . . . . . . . . . . . . . . . . . . . 5 3.1. Label-Index TLV . . . . . . . . . . . . . . . . . . . . . 5
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 . . . . . . . . . . . . 10
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 . . . . . . . . . . . . . . . . . . . 13 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
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 . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
The Segment Routing (SR) architecture leverages the source routing The Segment Routing (SR) architecture leverages the source routing
paradigm. A segment represents either a topological instruction such paradigm. A segment represents either a topological instruction such
as "go to prefix P following shortest path" or a service instruction. as "go to prefix P following shortest path" or a service instruction.
Other types of segments may be defined in the future. Other types of segments may be defined in the future.
A segment is identified through a Segment Identifier (SID). An SR A segment is identified through a Segment Identifier (SID). An SR
domain is defined as a single administrative domain for global SID domain is defined as a single administrative domain for global SID
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build their neighbor's Segment Routing Global Block (SRGB) are build their neighbor's Segment Routing Global Block (SRGB) are
included in [I-D.ietf-spring-segment-routing-mpls]). included in [I-D.ietf-spring-segment-routing-mpls]).
The Originator SRGB TLV may only appear in a BGP Prefix-SID attribute The Originator SRGB TLV may only appear in a BGP Prefix-SID attribute
attached to IPv4/IPv6 Labeled Unicast prefixes ([RFC8277]). It MUST attached to IPv4/IPv6 Labeled Unicast prefixes ([RFC8277]). It MUST
be ignored when received for other BGP AFI/SAFI combinations. Since be ignored when received for other BGP AFI/SAFI combinations. Since
the Label-Index TLV is required for IPv4/IPv6 prefix applicability, the Label-Index TLV is required for IPv4/IPv6 prefix applicability,
the Originator SRGB TLV will be ignored if it is not specified the Originator SRGB TLV will be ignored if it is not specified
consistent with Section 6. consistent with Section 6.
If a BGP speaker receives a node's SRGB as an attribute of the BGP-LS
Node NLRI and the BGP speaker also receives the same node's SRGB in a
BGP Prefix-SID attribute, then the received values should be the
same. If the values are different, the values advertised in the BGP-
LS NLRI SHOULD be preferred and an error should be logged.
4. Receiving BGP Prefix-SID Attribute 4. Receiving BGP Prefix-SID Attribute
A BGP speaker receiving a BGP Prefix-SID attribute from an External A BGP speaker receiving a BGP Prefix-SID attribute from an External
BGP (EBGP) neighbor residing outside the boundaries of the SR domain BGP (EBGP) neighbor residing outside the boundaries of the SR domain
MUST discard the attribute unless it is configured to accept the MUST discard the attribute unless it is configured to accept the
attribute from the EBGP neighbor. A BGP speaker SHOULD log an error attribute from the EBGP neighbor. A BGP speaker SHOULD log an error
for further analysis when discarding an attribute. for further analysis when discarding an attribute.
4.1. MPLS Dataplane: Labeled Unicast 4.1. MPLS Dataplane: Labeled Unicast
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boundary of the SR/administrative domain. Local BGP attribute boundary of the SR/administrative domain. Local BGP attribute
filtering policies and mechanisms are not standardized and, filtering policies and mechanisms are not standardized and,
consequently, beyond the scope of this document. consequently, beyond the scope of this document.
To prevent a Denial-of-Service (DoS) or Distributed-Denial-of-Service To prevent a Denial-of-Service (DoS) or Distributed-Denial-of-Service
(DDoS) attack due to excessive BGP updates with an invalid or (DDoS) attack due to excessive BGP updates with an invalid or
conflicting BGP Prefix-SID attribute, error log message rate-limiting conflicting BGP Prefix-SID attribute, error log message rate-limiting
as well as suppression of duplicate error log messages SHOULD be as well as suppression of duplicate error log messages SHOULD be
deployed. deployed.
Since BGP-LS is the preferred method for advertising SRGB
information, the BGP speaker SHOULD log an error if a BGP Prefix-SID
attribute is received with SRGB information different from that
received as an attribute of the same node's BGP-LS Node NLRI.
10. Contributors 10. Contributors
Keyur Patel Keyur Patel
Arrcus, Inc. Arrcus, Inc.
US US
Email: Keyur@arrcus.com Email: Keyur@arrcus.com
Saikat Ray Saikat Ray
Unaffiliated Unaffiliated
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