Troubleshooting BGP: A Practical Guide to Understanding and Troubleshooting BGP (Networking Technology)

Cover
Title Page
Copyright Page
About the Authors
Acknowledgments
Contents
Foreword
Introduction
Part I: BGP Fundamentals
	Chapter 1 BGP Fundamentals
		Border Gateway Protocol
			Autonomous System Numbers
			Path Attributes
			Loop Prevention
			Address Families
			BGP Sessions
		Inter-Router Communication
		BGP Messages
			OPEN
			Hold Time
			BGP Identifier
			KEEPALIVE
			UPDATE
			NOTIFICATION Message
		BGP Neighbor States
			Idle
			Connect
			Active
			OpenSent
			OpenConfirm
			Established
		Basic BGP Configuration
			IOS
			IOS XR
			NX-OS
			Verification of BGP Sessions
			Prefix Advertisement
			BGP Best-Path Calculation
		Route Filtering and Manipulation
		IBGP
			IBGP Full Mesh Requirement
			Peering via Loopback Addresses
		EBGP
			EBGP and IBGP Topologies
			Next-Hop Manipulation
		IBGP Scalability
			Route Reflectors
		Loop Prevention in Route Reflectors
		Out-of-Band Route Reflectors
			Confederations
		BGP Communities
		Route Summarization
			Aggregate-Address
			Flexible Route Suppression
			Selective Prefix Suppression
			Leaking Suppressed Routes
			Atomic Aggregate
			Route Aggregation with AS_SET
			Route Aggregation with Selective Advertisement of AS-SET
			Default Route Advertisement
			Default Route Advertisement per Neighbor
		Remove Private AS
		Allow AS
		LocalAS
		Summary
		References
Part II: Common BGP Troubleshooting
	Chapter 2 Generic Troubleshooting Methodologies
		Identifying the Problem
		Understanding Variables
		Reproducing the Problem
			Setting Up the Lab
			Configuring Lab Devices
			Triggering Events
		Sniffer-Packet Capture
			SPAN on Cisco IOS
			SPAN on Cisco IOS XR
			SPAN on Cisco NX-OS
			Remote SPAN
		Platform-Specific Packet Capture Tools
			Netdr Capture
			Embedded Packet Capture
			Ethanalyzer
		Logging
		Event Monitoring/Tracing
		Summary
		Reference
	Chapter 3 Troubleshooting Peering Issues
		BGP Peering Down Issues
			Verifying Configuration
			Verifying Reachability
			Find the Location and Direction of Packet Loss
			Verify Whether Packets Are Being Transmitted
			Use Access Control Lists to Verify Whether Packets Are Received
			Check ACLs and Firewalls in Path
			Verify TCP Sessions
			Simulate a BGP Session
			Demystifying BGP Notifications
			Decode BGP Messages
			Troubleshoot Blocked Process in IOS XR
			Verify BGP and BPM Process State
			Verify Blocked Processes
			Restarting a Process
			BGP Traces in IOS XR
			BGP Traces in NX-OS
			Debugs for BGP
			Troubleshooting IPv6 Peers
			Case Study—Single Session Versus Multisession
			Multisession Capability
			Single-Session Capability
		BGP Peer Flapping Issues
			Bad BGP Update
			Hold Timer Expired
			Interface Issues
			Physical Connectivity
			Physical Interface
			Input Hold Queue
			TCP Receive Queue
			MTU Mismatch Issues
			High CPU Causing Control-Plane Flaps
			Control Plane Policing
			CoPP on NX-OS
			Local Packet Transport Services
		Dynamic BGP Peering
			Dynamic BGP Peer Configuration
			Dynamic BGP Challenges
			Misconfigured MD5 Password
			Resource Issues in a Scaled Environment
			TCP Starvation
		Summary
		References
	Chapter 4 Troubleshooting Route Advertisement and BGP Policies
		Troubleshooting BGP Route Advertisement
			Local Route Advertisement Issues
			Route Aggregation Issues
			Route Redistribution Issues
			BGP Tables
			Receiving and Viewing Routes
		Troubleshooting Missing BGP Routes
			Next-Hop Check Failures
			Bad Network Design
			Validity Check Failure
			AS-Path
			Originator-ID/Cluster-ID
			BGP Communities
			BGP Communities: No-Advertise
			BGP Communities: No-Export
			BGP Communities: Local-AS (No Export SubConfed)
			Mandatory EBGP Route Policy for IOS XR
			Filtering of Prefixes by Route Policy
		Conditional Matching
			Access Control Lists (ACL)
			Prefix Matching
			Regular Expressions (Regex)
			UnderScore _
			Caret ^
			Dollar Sign $
			Brackets [ ]
			Hyphen -
			Caret in Brackets [^]
			Parentheses ( ) and Pipe |
			Period
			Plus Sign +
			Question Mark ?
			Asterisk *
			Looking Glass and Route Servers
			Conditionally Matching BGP Communities
		Troubleshooting BGP Router Policies
			IOS and NX-OS Prefix-Lists
			IOS and NX-OS AS-Path ACLs
			Route-Map Processing
			IOS and NX-OS Route-Maps
			IOS XR Route-Policy Language
			Incomplete Configuration of Routing Policies
		Conditional BGP Debugs
		Summary
		Further Reading
		References in This Chapter
	Chapter 5 Troubleshooting BGP Convergence
		Understanding BGP Route Convergence
			BGP Update Groups
			BGP Update Generation
		Troubleshooting Convergence Issues
			Faster Detection of Failures
			Jumbo MTU for Faster Convergence
			Slow Convergence due to Periodic BGP Scan
			Slow Convergence due to Default Route in RIB
			BGP Next-Hop Tracking
			Selective Next-Hop Tracking
			Slow Convergence due to Advertisement Interval
			Computing and Installing New Path
			Troubleshooting BGP Convergence on IOS XR
			Verifying Convergence During Initial Bring Up
			Verifying BGP Reconvergence in Steady State Network
			Troubleshooting BGP Convergence on NX-OS
		BGP Slow Peer
			BGP Slow Peer Symptoms
			High CPU due to BGP Router Process
			Traffic Black Hole and Missing Prefixes in BGP table
			BGP Slow Peer Detection
			Verifying OutQ value
			Verifying SndWnd
			Verifying Cache Size and Pending Replication Messages
			Workaround
			Changing Outbound Policy
			Advertisement Interval
			BGP Slow Peer Feature
			Static Slow Peer
			Dynamic Slow Peer Detection
			Slow Peer Protection
			Slow Peer Show Commands
		Troubleshooting BGP Route Flapping
		Summary
		Reference
Part III: BGP Scalability Issues
	Chapter 6 Troubleshooting Platform Issues Due to BGP
		Troubleshooting High CPU Utilization due to BGP
			Troubleshooting High CPU due to BGP on Cisco IOS
			High CPU due to BGP Scanner Process
			High CPU due to BGP Router Process
			High CPU Utilization due to BGP I/O Process
			Troubleshooting High CPU due to BGP on IOS XR
			Troubleshooting High CPU due to BGP on NX-OS
			Capturing CPU History
			Troubleshooting Sporadic High CPU Condition
			Troubleshooting Memory Issues due to BGP
			TCAM Memory
			Troubleshooting Memory Issues on Cisco IOS Software
			Troubleshooting Memory Issues on IOS XR
			Troubleshooting Memory Issues on NX-OS
			Restarting Process
		Summary
		References
	Chapter 7 Scaling BGP
		The Impact of Growing Internet Routing Tables
		Scaling Internet Table on Various Cisco Platforms
		Scaling BGP Functions
			Tuning BGP Memory
			Prefixes
			Managing the Internet Routing Table
			Paths
			Attributes
			Tuning BGP CPU
			IOS Peer-Groups
			IOS XR BGP Templates
			NX-OS BGP Peer Templates
			BGP Peer Templates on Cisco IOS
			Soft Reconfiguration Inbound Versus Route Refresh
			Dynamic Refresh Update Group
			Enhanced Route Refresh Capability
			Outbound Route Filtering (ORF)
			Prefix-Based ORF
			Extended Community–Based ORF
			BGP ORF Format
			BGP ORF Configuration Example
			Maximum Prefixes
			BGP Max AS
			BGP Maximum Neighbors
		Scaling BGP with Route Reflectors
			BGP Route Reflector Clusters
			Hierarchical Route Reflectors
			Partitioned Route Reflectors
			BGP Selective Route Download
			Virtual Route Reflectors
			BGP Diverse Path
			Shadow Route Reflectors
			Shadow Sessions
		Route Servers
		Summary
		References
	Chapter 8 Troubleshooting BGP Edge Architectures
		BGP Multihoming and Multipath
			Resiliency in Service Providers
			EBGP and IBGP Multipath Configuration
			EIBGP Multipath
			R1
			R2
			R3
			R4
			R5
			AS-Path Relax
		Understanding BGP Path Selection
			Routing Path Selection Longest Match
			BGP Best-Path Overview
			Weight
			Local Preference
			Locally Originated via Network or Aggregate Advertisement
			Accumulated Interior Gateway Protocol (AIGP)
			Shortest AS-Path
			Origin Type
			Multi-Exit Discriminator (MED)
			EBGP over IBGP
			Lowest IGP Metric
			Prefer the Oldest EBGP Path
			Router ID
			Minimum Cluster List Length
			Lowest Neighbor Address
		Troubleshooting BGP Best Path
			Visualizing the Topology
			Phase I—Initial BGP Edge Route Processing
			Phase II—BGP Edge Evaluation of Multiple Paths
			Phase III—Final BGP Processing State
			Path Selection for the Routing Table
		Common Issues with BGP Multihoming
			Transit Routing
			Problems with Race Conditions
			Peering on Cross-Link
			Expected Behavior
			Unexpected Behavior
			Secondary Verification Methods of a Routing Loop
			Design Enhancements
			Full Mesh with IBGP
			Problems with Redistributing BGP into an IGP
		Summary
		References
Part IV: Securing BGP
	Chapter 9 Securing BGP
		The Need for Securing BGP
		Securing BGP Sessions
			Explicitly Configured Peers
			IPv6 BGP Peering Using Link-Local Address
			BGP Session Authentication
			BGP Pass Through
			EBGP-Multihop
			BGP TTL Security
			Filtering
			Protecting BGP Traffic Using IPsec
		Securing Interdomain Routing
			BGP Prefix Hijacking
			S-BGP
			IPsec
			Public Key Infrastructure
			Attestations
			soBGP
			Entity Certificate
			Authorization Certificate
			Policy Certificate
			BGP SECURITY Message
			BGP Origin AS Validation
			Route Origination Authorization (ROA)
			RPKI Prefix Validation Process
			Configuring and Verifying RPKI
			RPKI Best-Path Calculation
		BGP Remote Triggered Black-Hole Filtering
		BGP Flowspec
			Configuring BGP Flowspec
		Summary
		References
Part V: Multiprotocol BGP
	Chapter 10 MPLS Layer 3 VPN (L3VPN)
		MPLS VPNs
		MPLS Layer 3 VPN (L3VPN) Overview
			Virtual Routing and Forwarding
			Route Distinguisher
			Route Target
			Multi-Protocol BGP (MP-BGP)
			Network Advertisement Between PE and CE Routers
		MPLS Layer 3 VPN Configuration
			VRF Creation and Association
			IOS VRF Creation
			IOS XR VRF Creation
			NX-OS VRF Creation
			Verification of VRF Settings and Connectivity
			Viewing VRF Settings and Interface IP Addresses
			Viewing the VRF Routing Table
			VRF Connectivity Testing Tools
			MPLS Forwarding
			BGP Configuration for VPNv4 and PE-CE Prefixes
			IOS BGP Configuration for MPLS L3VPN
			IOS XR BGP Configuration for MPLS L3VPN
			NX-OS BGP Configuration for MPLS L3VPN
			Verification of BGP Sessions and Routes
		Troubleshooting MPLS L3VPN
			Default Route Advertisement Between PE-CE Routers
			Problems with AS-PATH
			Suboptimal Routing with VPNv4 Route Reflectors
			Troubleshooting Problems with Route Targets
			MPLS L3VPN Services
			RT Constraints
			MPLS VPN Label Exchange
			MPLS Forwarding
		Summary
		References
	Chapter 11 BGP for MPLS L2VPN Services
		L2VPN Services
			Terminologies
			Virtual Private Wire Service
			Interworking
			Configuration and Verification
			VPWS BGP Signaling
			Configuration
			Virtual Private LAN Service
			Configuration
			Verification
			VPLS Autodiscovery Using BGP
			VPLS BGP Signaling
			Troubleshooting
		Summary
		References
	Chapter 12 IPv6 BGP for Service Providers
		IPv6 BGP Features and Concepts
			IPv6 BGP Next-Hop
			IPv6 Reachability over IPv4 Transport
			IPv4 Routes over IPv6 Next-Hop
			IPv6 BGP Policy Accounting
		IPv6 Provider Edge Routers (6PE) over MPLS
			6PE Configuration
			6PE Verification and Troubleshooting
		IPv6 VPN Provider Edge (6VPE)
			IPv6-Aware VRF
			6VPE Next-Hop
			Route Target
			6VPE Control Plane
			6VPE Data Plane
			6VPE Configuration
			6VPE Control-Plane Verification
			6VPE Data Plane Verification
		Summary
		References
	Chapter 13 VxLAN BGP EVPN
		Understanding VxLAN
			VxLAN Packet Structure
			VxLAN Gateway Types
		VxLAN Overlay
			VxLAN Flood-and-Learn Mechanism
			Configuration and Verification
			Ingress Replication
		Overview of VxLAN BGP EVPN
			Distributed Anycast Gateway
			ARP Suppression
			Integrated Route/Bridge (IRB) Modes
			Asymmetric IRB
			Symmetric IRB
			Multi-Protocol BGP
			Configuring and Verifying VxLAN BGP EVPN
		Summary
		References
Part VI: High Availability
	Chapter 14 BGP High Availability
		BGP Graceful-Restart
		BGP Nonstop Routing
		Bidirectional Forwarding Detection
			Asynchronous Mode
			Asynchronous Mode with Echo Function
			Configuration and Verification
			Troubleshooting BFD Issues
			BFD Session Not Coming Up
			BFD Session Flapping
		BGP Fast-External-Fallover
		BGP Add-Path
		BGP best-external
		BGP FRR and Prefix-Independent Convergence
			BGP PIC Core
			BGP PIC Edge
			Scenario 1—IP PE-CE Link/Node Protection on CE Side
			Scenario 2—IP MPLS PE-CE Link/Node Protection for Primary/ Backup
			BGP Recursion Host
		Summary
		References
Part VII: BGP: Looking Forward
	Chapter 15 Enhancements in BGP
		Link-State Distribution Using BGP
			BGP-LS NLRI
			BGP-LS Path Attributes
			BGP-LS Configuration
			IGP Distribution
			BGP Link-State Session Initiation
		BGP for Tunnel Setup
		Provider Backbone Bridging: Ethernet VPN (PBB-EVPN)
			EVPN NLRI and Routes
			EVPN Extended Community
			EVPN Configuration and Verification
		Summary
		References
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	J-L
	M
	N
	O
	P
	Q
	R
	S
	T
	U
	V
	W-Z