Use of BGP for routing in large-scale data centers
draft-ietf-rtgwg-bgp-routing-large-dc-05
Routing Area Working Group P. Lapukhov
Internet-Draft Facebook
Intended status: Informational A. Premji
Expires: February 1, 2016 Arista Networks
J. Mitchell, Ed.
July 31, 2015
Use of BGP for routing in large-scale data centers
draft-ietf-rtgwg-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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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 . . . . . . . . . . . . . . . . . 5
3. Data Center Topologies Overview . . . . . . . . . . . . . . . 6
3.1. Traditional DC Topology . . . . . . . . . . . . . . . . . 6
3.2. Clos Network topology . . . . . . . . . . . . . . . . . . 7
3.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Clos Topology Properties . . . . . . . . . . . . . . 8
3.2.3. Scaling the Clos topology . . . . . . . . . . . . . . 9
3.2.4. Managing the Size of Clos Topology Tiers . . . . . . 10
4. Data Center Routing Overview . . . . . . . . . . . . . . . . 11
4.1. Layer 2 Only Designs . . . . . . . . . . . . . . . . . . 11
4.2. Hybrid L2/L3 Designs . . . . . . . . . . . . . . . . . . 12
4.3. Layer 3 Only Designs . . . . . . . . . . . . . . . . . . 12
5. Routing Protocol Selection and Design . . . . . . . . . . . . 13
5.1. Choosing EBGP as the Routing Protocol . . . . . . . . . . 13
5.2. EBGP Configuration for Clos topology . . . . . . . . . . 14
5.2.1. EBGP Configuration Guidelines and Example ASN Scheme 15
5.2.2. Private Use ASNs . . . . . . . . . . . . . . . . . . 16
5.2.3. Prefix Advertisement . . . . . . . . . . . . . . . . 17
5.2.4. External Connectivity . . . . . . . . . . . . . . . . 18
5.2.5. Route Summarization at the Edge . . . . . . . . . . . 19
6. ECMP Considerations . . . . . . . . . . . . . . . . . . . . . 19
6.1. Basic ECMP . . . . . . . . . . . . . . . . . . . . . . . 20
6.2. BGP ECMP over Multiple ASNs . . . . . . . . . . . . . . . 21
6.3. Weighted ECMP . . . . . . . . . . . . . . . . . . . . . . 21
6.4. Consistent Hashing . . . . . . . . . . . . . . . . . . . 22
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