BGP Topology Discovery Requirements
draft-ymbk-lsvr-discovery-req-02

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Last updated 2019-04-21
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Network Working Group                                            R. Bush
Internet-Draft                                              Arrcus & IIJ
Intended status: Informational                                  K. Patel
Expires: October 23, 2019                                         Arrcus
                                                          April 21, 2019

                  BGP Topology Discovery Requirements
                    draft-ymbk-lsvr-discovery-req-02

Abstract

   For wide scale routing protocols to build their topology and
   reachability databases they need to discover the encapsulation data
   on a link, link IP layer 3 attributes, attributes for IP layer 3 and
   above protocols on that link, and link liveness.  We refer to this as
   neighbor discovery.  BGP-LS and its enhancements provide an API to
   present much of these data to BGP protocols, but do not directly
   collect these data.  This document explores the needs and criteria
   for the data needed.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on October 23, 2019.

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   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Architectural Considerations  . . . . . . . . . . . . . . . .   2
   3.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   In a massive scale datacenter or similar environment BGP([RFC4271])
   and BGP-like protocols, e.g.  BGP-SPF (see [I-D.ietf-lsvr-bgp-spf]),
   provide massive scale-out without centralization using a tried and
   tested scalable distributed control plane transport, offering a
   scalable routing solution.  But BGP4, BGP-SPF, and similar protocols
   need layer 3 topology discovery; meaning IP encapsulations on a link,
   layer 3 IP addressing data on a link, attributes for IP layer 3 and
   above protocols on that link, and assured link liveness from the
   network to build and maintain the routing topology.

   BGP-LS [RFC7752] and its extensions provide an API which BGP4 and
   BGP-SPF can use to get the and distribute topology data.  But BGP-LS
   itself does not gather the data, it merely presents it.  So the IP
   topology data must be gathered.

   What topology data do BGP-like protocols actually need?  What level
   of freshness is needed?  What are the requirements for scale,
   extensibility, security, etc?

2.  Architectural Considerations

   Massive Data Centers (MDCs) have on the order of 10,000 racks, often
   with two Top Of Rack (TOR) devices per rack, on the order of 40
   hardware servers per rack, each with order 100 virtual services or
   machines, each with their own layer 3 IP address.  Given service
   mobility, any initial IP address aggregation fragments over time.  To
   provide this level of scaling reliably, stably, and security imposes
   architectural constraints on any discovery protocol.

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