Cloud Native Data Center Networking 1st Edition by Dinesh G Dutt ISBN 1492045608 9781492045601

1. The Motivations for a New Network Architecture

The Application-Network Shuffle

The Network Design from the Turn of the Century

The Charms of Bridging

Building Scalable Bridging Networks

The Trouble with the Access-Aggregation-Core Network Design

Unscalability

Complexity

Failure Domain

Unpredictability

Inflexibility

Lack of Agility

The Stories Not Told

Summary

2. Clos: Network Topology for a New World

Introducing the Clos Topology

A Deeper Dive into the Clos Topology

Use of Homogeneous Equipment

Routing as the Fundamental Interconnect Model

Oversubscription in a Clos Topology

Interconnect Link Speeds

Practical Constraints

Fine-Grained Failure Domain

Scaling the Clos Topology

Comparing the Two Three-Tier Models

Application Matchup

Data Center Build Out

Implications of the Clos Topology

Rethinking Failures and Troubleshooting

Cabling

Simplified Inventory Management

Network Automation

Some Best Practices for a Clos Network

Use of Multiple Links Between Switches

Use of Spines as Only a Connector

Use of Chassis as a Spine Switch

Host Attach Models

Summary

References

3. Network Disaggregation

What Is Network Disaggregation?

Why Is Network Disaggregation Important?

Controlling Costs

Avoiding Vendor Lock-In

Standardization of Features

What Made Network Disaggregation Possible Now?

Difference in Network Operations with Disaggregation

Purchase and Support

First Boot

Open Network Installer Environment

How Does ONIE Work?

The Players in Network Disaggregation: Hardware

Packet-Switching Silicon

ODMs

CPU Complex

The Standards Bodies

Common Myths About Network Disaggregation

Some Best Practices for Engaging with Network Disaggregation

Summary

References

4. Network Operating System Choices

Requirements of a Network Device

The Rise of Software-Defined Networking and OpenFlow

More Details About SDN and OpenFlow

The Trouble with OpenFlow

OVS

The Effect of SDN and OpenFlow on Network Disaggregation

NOS Design Models

Location of Switch Network State

Programming the Switching Silicon

API

The Reasons Behind the Different Answers

User Interface

Comparing the NOS Models with Cloud Native NOS Requirements

Illustrating the Models with an Example

What Else Is Left for a NOS to Do?

Summary

References

5. Routing Protocol Choices

Routing Overview

How Routing Table Lookups Work

How Routes Are Chosen

Types of Routing Table Entries

RIB and FIB

Routing Protocols Overview

Distance Vector Protocols Versus Link-State Protocols

Distance Vector Dissected

Link-State Dissected

Summarizing Distance Vector Versus Link-State Route Exchange

Comparing Distance Vector and Link-State Protocols

Scaling in Link-State and Distance Vector Protocols

Multipathing in Distance Vector and Link-State Protocols

No News Is Good News

Propagation Delay in Link-State and Distance Vector Protocols

Multiprotocol Support

Unnumbered Interfaces

Routing Configuration Complexity

Routing Protocols in Clos Networks

Link-State Versus Distance Vector When Links or Nodes Fail

Route Summarization in Clos Networks

Security and Safeguards

Bidirectional Forwarding Detection

Requirements of a Routing Protocol in the Data Center

Basic Requirements

Advanced Requirements

Rare or Futuristic Requirements

Choosing the Routing Protocol for Your Network

Summary

References

6. Network Virtualization

What Is Network Virtualization?

Uses of Network Virtualization in the Data Center

Forcing Traffic to Take a Certain Path

Applications That Require L2 Adjacency

Cloud

Separating Switch Management Network from Data Traffic

Network Virtualization Models

Service Abstraction: L2 or L3

Inline Versus Overlay Virtual Networks

Network Tunnels: The Fundamental Overlay Construct

Benefits of Network Tunnels

The Drawbacks of Network Tunnels

Network Virtualization Solutions for the Data Center

VLAN

VRF

VXLAN

Other Network Virtualization Solutions

Practical Limits on the Number of Virtual Networks

Size of Virtual Network ID in Packet Header

Hardware Limitations

Scalability of Control Plane and Software

Deployment Model

Control Protocols for Network Virtualization

Relationship of Virtual and Physical Control Plane

The Centralized Control Model

The Protocol-Based Control Model

Vendor Support for Network Virtualization

Merchant Silicon

Software

Standards

Illustrating VXLAN Bridging and Routing

VXLAN Bridging Example: H1 to H5

VXLAN and Routing: H1 to H6

Summarizing VXLAN Bridging and Routing

Summary

7. Container Networking

Introduction to Containers

Namespaces

Network Namespaces

Virtual Ethernet Interfaces

Container Networking: Diving In

Single-Host Container Networking

Multihost Container Networking

Comparing Different Container Network Solutions

Kubernetes Networking

Summary

8. Multicast Routing

Multicast Routing: Overview

The Uses of Multicast Routing

Problems to Solve in Multicast Routing

Building a Multicast Tree

Multicast Routing Protocol

PIM Sparse Mode

Rendezvous Point

Building a Multicast Distribution Tree

Multiple RPs and MSDP

PIM-SM in the Data Center

PIM-SM and Unnumbered

Summary

9. Life on the Edge of the Data Center

The Problems

Connectivity Models

Why Connect to the External World?

Bandwidth Requirements for External Connectivity

Connecting the Clos Topology to the External World

Routing at the Edge

Services

Hybrid Cloud Connectivity

Summary

10. Network Automation

What Is Network Automation?

Who Needs Network Automation?

Does Network Automation Mean Learning Programming?

Why Is Network Automation Difficult?

The Trouble with IP Addresses and Interfaces

Scale

Network Protocol Configuration Complexity

Lack of Programmatic Access

Traditional Network OS Limitations

What Can Network Developers Do to Help Network Automation?

Tools for Network Automation

Automation Best Practices

Ansible: An Overview

Inventory

Playbooks

Ad Hoc Commands

Structuring Playbooks

A Typical Automation Journey

Glorified File Copy

Automate the Configuration That Was Not Device Specific

Template the Routing and Interface Configuration

More Templating and Roles

Some Observations from Fellow Journeymen

Validating the Configuration

Single Source of Truth

Commit/Rollback in the Age of Automation

Vagrant and Network Testing

Automating Verification

Summary

References

11. Network Observability

What Is Observability?

The Current State of Network Observability

The Disenchantments of SNMP

Box-by-Box Approach to Network Observability

Why Is Observability Difficult with Networking?

Observability in Data Center Networks: Special Characteristics

Decomposing Observability

The Mechanics of Telemetry

What Do We Gather?

How Do We Gather?

When Do We Gather?

Storing the Data

The Uses for Multiple Data Sources

Of Alerts and Dashboards

Summary

References

12. Rethinking Network Design

Standard, Simple Building Blocks

Network Disaggregation

Failure: Missing the Forest for the Trees

L2 Failure Model Versus L3 Failure Model

Simple Versus Complex Failures

Handling Upgrades

The Pursuit of Less

How the Right Architecture Helps

Feature Set Essentialism

Constraints on the Cloud Native Network Design Principles

Summary

13. Deploying OSPF

Why OSPF?

The Problems to Be Addressed

Determining Link-State Flooding Domains

Numbered Versus Unnumbered OSPF

Support for IPv6

Support for VRFs

Requirements for Running OSPF on Servers

OSPF Route Types

The Messiness of Stubbiness

OSPF Timers

Dissecting an OSPF Configuration

Configuration for Leaf-Spine in a Two-Tier Clos Topology: IPv4

Configuration for Leaf-Spine in a Two-Tier Clos Topology: IPv6

Configuration with Three-Tier Clos Running OSPF

Configuration with Servers Running OSPF: IPv4

Summarizing Routes in OSPF

OSPF and Upgrades

Best Practices

Summary

14. BGP in the Data Center

Basic BGP Concepts

BGP Protocol Overview

BGP Peering

BGP State Machine

Autonomous System Number

BGP Capabilities

BGP Attributes, Communities, Extended Communities

BGP Best-Path Computation

Support for Multiple Protocols

BGP Messages

Adapting BGP to the Data Center

eBGP Versus iBGP

eBGP: Flying Solo

Private ASNs

BGP’s ASN Numbering Scheme

Multipath Selection

Fixing BGP’s Convergence Time

Summary

15. Deploying BGP

Core BGP Configuration Concepts

Traditional Configuration for a Two-Tier Clos Topology: IPv4

Peer Group

Routing Policy

Route Maps: Implementation of Routing Policy

Providing Sane Defaults for the Data Center

BGP Unnumbered: Eliminating Pesky Interface IP Addresses

A remote-as by Any Name

How Unnumbered Interfaces Work with BGP

Final Observations on BGP Configuration in FRR

Unnumbered BGP Support in Routing Stacks

Summary

Configuring IPv6

BGP and VRFs

Peering with BGP Speakers on the Host

BGP Dynamic Neighbors

BGP and Upgrades

AS_PATH Prepend

GRACEFUL_SHUTDOWN Community

Max-MED

Best Practices

Summary

16. EVPN in the Data Center

Why Is EVPN Popular?

The Problems a Network Virtualization Control Plane Must Address

Where Does a VTEP Reside?

One Protocol to Rule Them All, Or…?

iBGP Characteristics

Separate Underlay and Overlay Protocols

eBGP Only

BGP Constructs to Support Virtual Network Routes

Route Distinguisher

Route Target

FRR’s use of RD and RT

EVPN Route Types

Communicating Choice of BUM Handling

EVPN and Bridging

EVPN Bridging with Ingress Replication

EVPN Bridging with Routed Multicast Underlay

Handling MAC Moves

Support for Dual-Attached Hosts

Host-Switch Interconnect Model

VXLAN Model for Dual-Attached Hosts

Switch Peering Options

Handling Link Failures

Avoiding Duplicate Multidestination Frames

ARP/ND Suppression

EVPN and Routing

Centralized Versus Distributed Routing

Symmetric Versus Asymmetric Routing

Route Advertisements

The Use of VRFs

Deploying EVPN in Large Networks

Summary

17. Deploying Network Virtualization

The Configuration Scenarios

Device-Local Configuration

Single eBGP Session

OSPF Underlay, iBGP Overlay

allowas-in Versus Separate ASN

PIM/MSDP Configuration

EVPN on the Host

Best Practices

Summary

18. Validating Network Configuration

Validating the Network State

System Validation

Cabling Validation

Using Ansible to Validate Cabling

Interface Configuration Validation

Automating Interface Configuration Validation

Routing Configuration Validation

Validating an OSPF Configuration

Validating a BGP Configuration

Stripping the Private ASNs

Validating Network Virtualization

Application’s Network Validation

Data-Plane Validation

Summary

19. Coda

Glossary

Index