Use of BGP for routing in large-scale data centers
draft-lapukhov-bgp-routing-large-dc-05

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Replaced by RFC 7938, RFC 7938
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Network Working Group                                        P. Lapukhov
Internet-Draft                                     Microsoft Corporation
Intended status: Informational                                 A. Premji
Expires: January 16, 2014                                Arista Networks
                                                        J. Mitchell, Ed.
                                                   Microsoft Corporation
                                                           July 15, 2013

           Use of BGP for routing in large-scale data centers
                 draft-lapukhov-bgp-routing-large-dc-05

Abstract

   Some network operators build and operate data centers that support
   over one hundred thousand servers.  In this document, such data
   centers are referred to as "large-scale" to differentiate them from
   smaller infrastructures.  Environments of this scale have a unique
   set of network requirements with an emphasis on operational
   simplicity and network stability.  This document summarizes
   operational experience in designing and operating large-scale data
   centers using BGP as the only routing protocol.  The intent is to
   report on a proven and stable routing design that could be leveraged
   by others in the industry.

Status of This Memo

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Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Lapukhov, et al.        Expires January 16, 2014                [Page 1]
Internet-Draft     draft-lapukhov-bgp-routing-large-dc         July 2013

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Network Design Requirements . . . . . . . . . . . . . . . . .   4
     2.1.  Bandwidth and Traffic Patterns  . . . . . . . . . . . . .   4
     2.2.  CAPEX Minimization  . . . . . . . . . . . . . . . . . . .   4
     2.3.  OPEX Minimization . . . . . . . . . . . . . . . . . . . .   5
     2.4.  Traffic Engineering . . . . . . . . . . . . . . . . . . .   5
     2.5.  Summarized Requirements . . . . . . . . . . . . . . . . .   6
   3.  Data Center Topologies Overview . . . . . . . . . . . . . . .   6
     3.1.  Traditional DC Topology . . . . . . . . . . . . . . . . .   6
     3.2.  Clos Network topology . . . . . . . . . . . . . . . . . .   7
       3.2.1.  Clos Topology Overview  . . . . . . . . . . . . . . .   7
       3.2.2.  Clos Topology Properties  . . . . . . . . . . . . . .   8
       3.2.3.  Scaling the Clos topology . . . . . . . . . . . . . .   8
       3.2.4.  Managing the Size of Clos Topology Tiers  . . . . . .   9
   4.  Data Center Routing Overview  . . . . . . . . . . . . . . . .  10
     4.1.  Layer 2 Only Designs  . . . . . . . . . . . . . . . . . .  10
     4.2.  Hybrid L2/L3 Designs  . . . . . . . . . . . . . . . . . .  11
     4.3.  Layer 3 Only Designs  . . . . . . . . . . . . . . . . . .  12
   5.  Routing Protocol Selection and Design . . . . . . . . . . . .  12
     5.1.  Choosing EBGP as the Routing Protocol . . . . . . . . . .  12
     5.2.  EBGP Configuration for Clos topology  . . . . . . . . . .  14
       5.2.1.  Example ASN Scheme  . . . . . . . . . . . . . . . . .  14
       5.2.2.  Private Use BGP ASNs  . . . . . . . . . . . . . . . .  15
       5.2.3.  Prefix Advertisement  . . . . . . . . . . . . . . . .  16
       5.2.4.  External Connectivity . . . . . . . . . . . . . . . .  16
       5.2.5.  Route Aggregation at the Edge . . . . . . . . . . . .  17
   6.  ECMP Considerations . . . . . . . . . . . . . . . . . . . . .  18
     6.1.  Basic ECMP  . . . . . . . . . . . . . . . . . . . . . . .  18
     6.2.  BGP ECMP over Multiple ASNs . . . . . . . . . . . . . . .  19
     6.3.  Weighted ECMP . . . . . . . . . . . . . . . . . . . . . .  20
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