Blog Posts in 2023

December 2023

• End-of-Year Cleanup: OSPF Blog Posts (21 Dec 2023)
• Setting Source IP Address on Traffic Started by a Multihomed Host (20 Dec 2023)
• BGP Challenge: Merge Autonomous Systems (19 Dec 2023)
• Review: Unnumbered Interfaces in netlab (18 Dec 2023)
• Worth Reading: The AI Supply Paradox (17 Dec 2023)
• Worth Reading: State-of-the-Art AI (16 Dec 2023)
• Video: Language Model Basics (15 Dec 2023)
• netlab: Version-Specific Topology Files (14 Dec 2023)
• BGP Labs: Use BGP Communities in a Routing Policy (13 Dec 2023)
• Interviewing a Network Engineer Using a Single Scenario (12 Dec 2023)
• Response: Vendor Network Automation Tools (11 Dec 2023)
• Worth Reading: Network CI and Open Source (10 Dec 2023)
• Worth Exploring: SRv6 Test Topologies (09 Dec 2023)
• Video: netlab IP Address Management (IPAM) (08 Dec 2023)
• AMS-IX Outage: Layer-2 Strikes Again (07 Dec 2023)
• BGP Labs: Use BGP Route Reflectors (06 Dec 2023)
• netlab 1.7.0: Lab Validation, Fabrics, BGP Nerd Knobs (05 Dec 2023)
• The BGP Origin Attribute (04 Dec 2023)
• Worth Reading: DNS over IPv6 (03 Dec 2023)
• Worth Reading: Use of HTTPS DNS Resource Records (02 Dec 2023)

November 2023

• The BGP Multi-Exit Discriminator (MED) Saga (30 Nov 2023)
• BGP Labs: Set BGP Communities on Outgoing Updates (29 Nov 2023)
• Can a Router Use the Default Route to Reach BGP Next Hops? (27 Nov 2023)
• Worth Reading: Network Automation with GitHub Actions (26 Nov 2023)
• Worth Reading: Going CCNP Emeritus (25 Nov 2023)
• Video: Language Models in AI/ML Landscape (24 Nov 2023)
• BGP Labs: AS-Path Prepending (23 Nov 2023)
• Why Do We Need BGP Identifiers? (22 Nov 2023)
• Is BGP TTL Security Any Good? (21 Nov 2023)
• VXLAN/EVPN Layer-3 Handoff (L3Out) on Arista EOS (20 Nov 2023)
• Video: Outages Caused by Bugs in BGP Implementations (17 Nov 2023)
• Worth Reading: Cloudflare Control Plane Outage (16 Nov 2023)
• BGP Labs: Using Multi-Exit Discriminator (MED) (15 Nov 2023)
• Is Anyone Using netlab on Windows? (14 Nov 2023)
• LAN Data Link Layer Addressing (13 Nov 2023)
• Git Rebase: What Can Go Wrong? (11 Nov 2023)
• Video: Kubernetes Calico Plugin (10 Nov 2023)
• BGP Labs: Using BGP Local Preference (09 Nov 2023)
• Open BGP Daemons: There's So Many of Them (08 Nov 2023)
• Rapid Progress in BGP Route Origin Validation (07 Nov 2023)
• Fibre Channel Addressing (06 Nov 2023)
• Worth Reading: Confusing Git Terminology (04 Nov 2023)
• Video: Hacking BGP for Fun and Profit (03 Nov 2023)
• BGP Labs: Build a Transit Network with IBGP (02 Nov 2023)
• Worth Reading: Taming the BGP Reconfiguration Transients (01 Nov 2023)

October 2023

• Weird: vJunos Evolved 23.2R1.5 Declines DHCP Address (30 Oct 2023)
• Worth Exploring: BGP from Theory to Practice (29 Oct 2023)
• Early Data-Link Layer Addressing (27 Oct 2023)
• BGP Labs: Multivendor External Routers (25 Oct 2023)
• netlab 1.6.4: Support for Multi-Lab Projects; More BGP Goodies (24 Oct 2023)
• Video: History of BGP Route Leaks (23 Oct 2023)
• BGP Labs: Build Larger Networks with IBGP (18 Oct 2023)
• Will Network Devices Reject BGP Sessions from Unknown Sources? (17 Oct 2023)
• Worth Reading: AI Risks (16 Oct 2023)
• BGP Labs: TCP-AO Protection of BGP Sessions (12 Oct 2023)
• netlab 1.6.3: BGP Nerd Knobs (11 Oct 2023)
• Worth Reading: Some Thoughts on Digital Twins (08 Oct 2023)
• Worth Reading: Introduction of EVPN at DE-CIX (07 Oct 2023)
• Video: What Is Software-Defined Data Center (06 Oct 2023)
• netlab 1.6.2: More Reporting Goodies (05 Oct 2023)
• BGP Labs: Route Aggregation (04 Oct 2023)
• What Is Ultra Ethernet All About? (03 Oct 2023)
• BGP Session Security: Be Very Skeptical (02 Oct 2023)
• Worth Reading: Flow Distribution Across ECMP Paths (01 Oct 2023)

September 2023

• Worth Reading: Single-Port LAGs (30 Sep 2023)
• How GitHub Saved My Day (28 Sep 2023)
• BGP Labs: Use BFD to Speed Up Convergence (27 Sep 2023)
• Why Do We Need Source IP Addresses in IP Headers? (26 Sep 2023)
• Does EVPN/VXLAN over SD-WAN Make Sense? (25 Sep 2023)
• Repost: L2 Is Bad (22 Sep 2023)
• BGP Labs: Protect EBGP Sessions (21 Sep 2023)
• Addresses in a Networking Stack (20 Sep 2023)
• Names, Addresses, and Routes (19 Sep 2023)
• Dataplane MAC Learning with EVPN (18 Sep 2023)
• Worth Reading: Where Are the Self-Driving Cars? (14 Sep 2023)
• BGP Labs: Bidirectional Route Redistribution (13 Sep 2023)
• DHCP Relaying Across a Firewall (12 Sep 2023)
• OSPF ECMP with Unnumbered IPv4 Interfaces (11 Sep 2023)
• Reliable ECMP with Static Routing (08 Sep 2023)
• Case Study: BGP Routing Policy (07 Sep 2023)
• Layer-3 WAN Handoff (L3Out) in VXLAN/EVPN Fabrics (06 Sep 2023)
• Random Thoughts on Zero-Trust Architecture (05 Sep 2023)
• BGP Labs: Simple Routing Policy Tools (04 Sep 2023)
• Lifetime ipSpace.net Subscription (01 Sep 2023)

August 2023

• OSPF and ARP on Unnumbered IPv4 Interfaces (31 Aug 2023)
• ARP and Static Routes (30 Aug 2023)
• Worth Reading: Looking Inside Large Language Models (29 Aug 2023)
• ARP Details Behind the Scenes (28 Aug 2023)
• BGP Labs: The Basics (24 Aug 2023)
• How GitHub Learned How Hard Distributed Systems Are (23 Aug 2023)
• Engagement Farming (22 Aug 2023)
• netlab 1.6.1: BGP Reports, Markdown Support (21 Aug 2023)
• Getting Comfortable with the Command Line (18 Aug 2023)
• Free Subscription No Longer Needed to Watch the ipSpace.net Videos (16 Aug 2023)
• Worth Reading: Networking for AI Workloads (14 Aug 2023)
• New Project: BGP Hands-On Labs (03 Aug 2023)
• netlab 1.6.0: New Commands, Reports, and External Connectivity (01 Aug 2023)

July 2023

• Worth Reading: MP-TCP in Hybrid Access Networks (24 Jul 2023)
• Worth Reading: Eyes Like Saucers (20 Jul 2023)
• Multipath TCP (MPTCP) Resources (18 Jul 2023)
• Configuring Linux Traffic Control in a Sane Way (11 Jul 2023)
• Fun Reading: History of the Early Internet (09 Jul 2023)
• Worth Watching: Ethernet Thick Yellow Cable (08 Jul 2023)
• Worth Reading: Another BGP Session Reset Bug (02 Jul 2023)
• Worth Reading: AI Does Not Help Programmers (01 Jul 2023)

June 2023

• Worth Reading: What Is Going on With BGP? (25 Jun 2023)
• Worth Reading: Always the Same Warning Signs (24 Jun 2023)
• Summer Break 2023 (22 Jun 2023)
• Use FRR Containers to Learn Routing Protocol Fundamentals (21 Jun 2023)
• When a Device Without an IP Address Wants to Play the IP Game (20 Jun 2023)
• Exercise: Fix BGP Route Leaks (19 Jun 2023)
• Worth Reading: Some Blogging Myths (18 Jun 2023)
• Worth Reading: A Primer on Communication Fundamentals (17 Jun 2023)
• Please Respond: MANRS Customer Survey (15 Jun 2023)
• EIGRP Stub Routers (14 Jun 2023)
• Classification of BGP Route Leaks (RFC 7908) (13 Jun 2023)
• netlab Release 1.5.4: New Junos Platforms (12 Jun 2023)
• Worth Reading: Building Stuff with Large Language Models Is Hard (11 Jun 2023)
• Spoofing ICMP Redirects for Fun and Profit (10 Jun 2023)
• Video: SD-WAN Security (09 Jun 2023)
• Are LACP Fast Timers Any Good? (08 Jun 2023)
• Distributed Systems Resources (07 Jun 2023)
• EIGRP Third-Party Next Hops (06 Jun 2023)
• Default EBGP Policy (RFC 8212) (05 Jun 2023)
• Worth Reading: Internet WAN Edge Design (04 Jun 2023)
• Worth Reading: Unbounded TCP Memory Usage (03 Jun 2023)
• Video: Link State Routing Protocol Implementations (02 Jun 2023)
• Source IP Address in Multicast Packets (01 Jun 2023)

May 2023

• NTP in a Nutshell (31 May 2023)
• Path Failure Detection on Multi-Homed Servers (30 May 2023)
• Goodbye Twitter. It Was Fun While It Lasted (29 May 2023)
• Worth Reading: Cargo Cult AI (28 May 2023)
• Worth Reading: Building Trustworthy AI (27 May 2023)
• Network Security Vulnerabilities: the Root Causes (26 May 2023)
• Inter-VRF DHCP Relaying with Redundant DHCP Servers (25 May 2023)
• Dealing with Cisco ACI Quirks (23 May 2023)
• Simplify netlab Topologies with Link Groups (22 May 2023)
• Worth Reading: Trapped by Technology Fallacies (21 May 2023)
• Why Is Source Address Validation Still a Problem? (20 May 2023)
• Video: Types of Switching ASICs (19 May 2023)
• Find the Optimal Level of Automation Abstraction (18 May 2023)
• New: Disaster Recovery Resources (17 May 2023)
• ITNOG 7 Wrap-up (16 May 2023)
• netlab Release 1.5.3: libvirt Public Networks (15 May 2023)
• Worth Reading: Official Ansible Collection for SR Linux (14 May 2023)
• Service Insertion with BGP FlowSpec (13 May 2023)
• Video: Kubernetes Container Networking Interface (CNI) (12 May 2023)
• MLAG Clusters without a Physical Peer Link (11 May 2023)
• Is ChatGPT an Efficiency Multiplier? (10 May 2023)
• Modifying BGP Behavior with xBGP API (09 May 2023)
• Building a DMVPN Test Lab with netlab (08 May 2023)
• MUST READ: End-to-End Arguments in System Design (07 May 2023)
• Worth Reading: IPv6 Deployment Status (06 May 2023)
• Video: 400GbE Optics (05 May 2023)
• Silent Hosts in EVPN Fabrics (04 May 2023)
• Small Site EBGP-Only Design (03 May 2023)
• netlab Release 1.5.2: Aruba CX, External Tools, Tunnel Interfaces (02 May 2023)

April 2023

• Interesting: BGP Zombie Outbreak on Juniper Routers (30 Apr 2023)
• CloudFlare: From IP packets to HTTP (29 Apr 2023)
• Advantages and Drawbacks of EVPN-based Multihoming (28 Apr 2023)
• Why Is OSPF (and BGP) More Complex than STP? (27 Apr 2023)
• Is Dynamic MAC Learning Better Than EVPN? (26 Apr 2023)
• IPv6 Security in Layer-2 Firewalls (25 Apr 2023)
• Use Existing (DMVPN) Device Configurations in netlab (24 Apr 2023)
• Systems Design: What We Hope We Know (23 Apr 2023)
• 180 Gbps Software-Only Linux Router (22 Apr 2023)
• Video: SD-WAN CPE Architecture (21 Apr 2023)
• Multi-Vendor EVPN Fabrics (20 Apr 2023)
• New: Network Infrastructure as Code Resources (19 Apr 2023)
• IPv6 Addressing on Point-to-Point Links (18 Apr 2023)
• Using VLAN and VRF Links in netlab Topologies (17 Apr 2023)
• ChatGPT Explaining the Need for iSCSI CRC (16 Apr 2023)
• Worth Reading: Was MPLS TE Worth the Effort? (15 Apr 2023)
• Video: netlab Topology File (14 Apr 2023)
• Building a Small Network with ChatGPT (13 Apr 2023)
• Should I Care About RPKI and Internet Routing Security? (12 Apr 2023)
• DHCP Relaying with Redundant DHCP Servers (11 Apr 2023)
• Turning WiFi into a Thick Yellow Cable (07 Apr 2023)
• Kicking the Tires of GitHub Copilot (06 Apr 2023)
• New: High Availability Clusters in Networking (05 Apr 2023)
• netlab Release 1.5.1: VLAN and VRF Links (04 Apr 2023)
• DHCP Relaying in EVPN VRFs (03 Apr 2023)
• Worth Reading: The Death of CLI (02 Apr 2023)

March 2023

• Video: Sample Kubernetes SDN Implementations (31 Mar 2023)
• ChatGPT on BGP Routing Security (30 Mar 2023)
• Studying EVPN to Prepare for a Job Interview (29 Mar 2023)
• What Happened to Leaf Switches with Four Uplinks? (28 Mar 2023)
• DHCP Relaying in VXLAN Segments (27 Mar 2023)
• Worth Reading: Off-Path Firewall with Traffic Engineering (26 Mar 2023)
• Worth Reading: The Dangers of Knowing Everything (25 Mar 2023)
• Video: Chassis Switch Architectures (24 Mar 2023)
• Will ChatGPT Replace Stack Overflow? (23 Mar 2023)
• New: CI/CD in Networking Resource Page (22 Mar 2023)
• External Links on Spine Switches (21 Mar 2023)
• Test VRF-Aware DHCP Relaying with netlab (20 Mar 2023)
• Worth Reading: History of 8-bit Bytes (19 Mar 2023)
• Worth Exploring: OSPF Watcher (18 Mar 2023)
• Video: vPC Fabric Peering with EVPN Multihoming (17 Mar 2023)
• Advantages of Using Generalized TTL Security Mechanism (GTSM) with EBGP (16 Mar 2023)
• First Steps in IPv6 Deployments (15 Mar 2023)
• Leaf-and-Spine Fabrics Between Theory and Reality (14 Mar 2023)
• Test DHCP Relaying with netlab (13 Mar 2023)
• Worth Reading: Putting Large Language Models in Context (12 Mar 2023)
• Worth Reading: The War on Expertise (11 Mar 2023)
• Video: SD-WAN Backend Architecture (10 Mar 2023)
• DHCP Relaying Details (09 Mar 2023)
• New: Anycast Resource Page (08 Mar 2023)
• Dynamic MAC Learning: Hardware or CPU Activity? (07 Mar 2023)
• netlab: Change Stub Networks into Loopbacks (06 Mar 2023)
• Video: Getting Started with netlab (03 Mar 2023)
• History of IP TTL in EBGP Sessions (02 Mar 2023)
• Feedback: Microsoft Azure Networking (01 Mar 2023)

February 2023

• Alternatives to IBGP within Multihomed Sites (28 Feb 2023)
• Suspending Devices in netlab Labs (27 Feb 2023)
• Video: Packet Buffers in Data Center ASICs (24 Feb 2023)
• How Many Spines Should a Leaf-and-Spine Fabric Have? (23 Feb 2023)
• Measuring Virtual Network Device Boot Times (22 Feb 2023)
• Some Operations Are Not Worth Automating (21 Feb 2023)
• Start Multiple netlab Labs on the Same Server (20 Feb 2023)
• Worth Reading: On ChatGPT (18 Feb 2023)
• Video: Link State Routing Protocol Basics (17 Feb 2023)
• Feedback: Designing Active/Active and Disaster Recovery Data Centers (16 Feb 2023)
• CE-to-CE IBGP Session in a Multihomed Site (15 Feb 2023)
• MUST READ: Machine Learning for Network and Cloud Engineers (14 Feb 2023)
• Start Large netlab Topologies in Smaller Batches (13 Feb 2023)
• Video: Kubernetes SDN Architecture (10 Feb 2023)
• Real-Life Not-Exactly-Networking AI Use Case (09 Feb 2023)
• Response: Nothing Works (in Enterprise IT) (08 Feb 2023)
• Improve BGP Startup Time on Cisco IOS (07 Feb 2023)
• Mix Containers and VMs with netlab Release 1.5.0 (06 Feb 2023)
• Worth Reading: 2 Mpps on a Pentium CPU (04 Feb 2023)
• Video: Migrating into a Cloud (03 Feb 2023)
• IRB Models: Edge Routing (02 Feb 2023)
• Response: Complexities of Network Automation (01 Feb 2023)

January 2023

• Design Clinic: Small-Site IPv6 Multihoming (31 Jan 2023)
• netlab Release 1.5.0: Larger Lab Topologies (30 Jan 2023)
• Worth Reading: A Debugging Manifesto (29 Jan 2023)
• MUST READ: Nothing Works (28 Jan 2023)
• Built.fm Podcast with David Gee (27 Jan 2023)
• Hiding Malicious Packets Behind LLC SNAP Header (26 Jan 2023)
• Response: Network Automation Expert Beginners (25 Jan 2023)
• Will DPUs Change the Network? (24 Jan 2023)
• netlab: Building a Layer-2 Fabric (23 Jan 2023)
• Worth Reading: Do We Need Network Automation (22 Jan 2023)
• Worth Exploring: OMNI and AERO (21 Jan 2023)
• Video: 2023 Network Engineer Path to Success (20 Jan 2023)
• Relationships between Layer-2 (VLAN) and Layer-3 (Subnet) Segments (19 Jan 2023)
• Feedback: Docker Networking Deep Dive (18 Jan 2023)
• Network Automation Expert Beginners (17 Jan 2023)
• netlab Release 1.4.3: Cisco IOS XRv, MPLS on FRR (16 Jan 2023)
• Worth Reading: Routing Protocol Implementation Evaluation (15 Jan 2023)
• Lack of Use Cases: a Lesson about Handling Hype (14 Jan 2023)
• Video: MLAG with EVPN Deep Dive (13 Jan 2023)
• State of LDPv6 and 6PE (12 Jan 2023)
• Updates: AWS Networking (11 Jan 2023)
• Is It Time to Replace TCP in Data Centers? (10 Jan 2023)
• netlab Release 1.4.2: Juniper vMX and Junos Features (09 Jan 2023)