Cloud Native Data Center Networking: Architecture, Protocols, and Tools

Copyright
Table of Contents
Preface
	Audience
	How This Book Is Organized
	Software Used in This Book
	Conventions Used in This Book
	Using Code Examples
	O’Reilly Online Learning
	How to Contact Us
	Acknowledgments
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 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
Chapter 19. Coda
Glossary
Index
About the Author
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