EVPN/VXLAN Troubleshooting Checklist: Fix Host Reachability in a Leaf-Spine Fabric

EVPN/VXLAN troubleshooting becomes much easier when you stop treating it as a magic overlay and split the fault into three layers: local switching, BGP EVPN control plane and VXLAN data plane. This guide gives a practical checklist for the common case: two endpoints should communicate through a leaf-spine fabric, but ping, ARP, TCP or a VM migration test fails.

The examples use documentation-style names such as leaf-1, vni-10100 and RFC 5737/RFC 3849 addressing. Replace them with your platform commands and real values in the lab, but keep the same order of operations.

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AI Cluster Networking: Practical BGP EVPN/VXLAN Checklist for Small GPU Pods

AI cluster networking often fails in ordinary places: an underlay route is missing, an EVPN route target is wrong, a VTEP is silent, or storage traffic accidentally shares a failure domain with GPU traffic. The hardware may be expensive, but the most reliable design pattern is still a boring, testable leaf-spine fabric with clear separation between underlay, overlay and tenant policy.

This practical checklist is written for small and medium AI labs, private GPU pods and data-center teams that want a repeatable BGP EVPN/VXLAN design without turning every troubleshooting session into a vendor-specific archaeology project.

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Backup Network Segmentation Against Ransomware: Practical VLAN and Firewall Design

Backup network segmentation is one of the cheapest ways to reduce ransomware blast radius, but it is often designed too late: after the backup repository already lives in the same flat VLAN as users, servers and admin workstations. The result is predictable. If an attacker gets domain credentials or lands on a privileged desktop, the backup platform becomes just another target to encrypt, delete or silently corrupt.

This practical design guide shows a small-office, branch or small data center pattern that separates backup management, backup data and immutable/offline copies. It is intentionally vendor-neutral and fits firewalls, L3 switches or SD-WAN edges. For broader design context, see the Start Here networking topics, Data Center Networking and Resources pages.

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BGP Unnumbered Leaf-Spine Underlay: Practical EVPN/VXLAN Fabric Guide

BGP unnumbered for a leaf-spine underlay is one of those designs that looks small on paper but removes a surprising amount of operational noise. Instead of assigning and tracking an address pair for every point-to-point fabric link, the switches form eBGP sessions over IPv6 link-local addresses and advertise the loopbacks needed by the EVPN/VXLAN overlay.

This article is a practical checklist for engineers building a small data center fabric, AI/GPU cluster network, or lab where the main goal is simple: make the underlay boring, repeatable and easy to troubleshoot before adding VXLAN services.

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Network Automation Workflow with Git and Ansible: Practical Guide for Data Center Engineers

Network automation becomes useful when it removes repetitive risk, not when it creates a second uncontrolled way to break the fabric. A realistic starting point for a small data center team is simple: use Git as the source of truth for intended changes, Ansible to render and push configuration, and a repeatable verification checklist before and after each change.

This guide uses a concrete scenario: an 8-leaf / 2-spine EVPN/VXLAN fabric that supports virtualization, backup, storage and a small AI/GPU rack. The team needs to add new application networks frequently, but every manual VLAN/VNI change touches multiple switches and is easy to mistype.

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Weekly BGP Table Watch: IPv4, IPv6 and ASN Changes — 2026-08-03

The global BGP table keeps moving every day. This weekly BGP Table Watch snapshot tracks IPv4 prefixes, IPv6 prefixes, visible ASNs and the largest routing-table changes reported during the last week.

The goal is not to alarm on every change. BGP is noisy by design. The goal is to build a simple operational habit: watch the size of the routing table, notice large origin-AS changes, and keep an eye on where new ASNs and route withdrawals appear.

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AI-Ready Leaf-Spine Network: Practical Guide for Small GPU Clusters

AI-ready leaf-spine network design sounds like something only hyperscalers need, but the same problems now appear in smaller rooms: one rack with two to eight GPU servers, a storage node, a few 25/100GbE links, and a team asking why training jobs slow down when backups or tenant traffic start moving.

This guide uses a concrete scenario: a small company or lab is building a 4-node GPU cluster. Each server has two 25GbE NICs for general traffic and optionally one 100GbE NIC for GPU/RDMA traffic. The goal is not to copy a hyperscale fabric. The goal is to make sane purchasing and configuration decisions before the first expensive GPU server is cabled.

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Secure Home Network with VLANs: Practical Guide for Small Office Buyers

A secure home network with VLANs is no longer only a lab topic. A 2.5 Gb/s Internet line, several Wi-Fi 6E or Wi-Fi 7 access points, cameras, smart TVs, work laptops and a small NAS can quickly become a flat network where every device can see everything else. That is convenient until one cheap IoT device, compromised camera or infected family laptop reaches your work machine or backup storage.

This guide uses a concrete scenario: a 200 m² home or small office with 2 adults working remotely, 1 NAS, 4 cameras, 2 access points, 25-40 client devices and a budget between $750 and $2,500. The goal is not a perfect enterprise design. The goal is a practical design you can buy, configure and verify.

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OSPF Network Types Explained: How They Work and Where They Break

OSPF network types are a small configuration detail with a big operational impact. They decide whether routers elect a DR/BDR, whether a Type-2 Network LSA appears, how neighbors form, and how easy the topology is to reason about during an outage. In many networks OSPF “just works” until a VLAN handoff, SVI, or routed link behaves differently on each side.

This guide focuses on the practical side: what the common OSPF network types mean, when to use point-to-point instead of broadcast, and how to troubleshoot neighbor states without jumping straight into random changes.

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Management Plane Security: Practical Guide for Network Engineers

Management plane security is the quiet control layer that decides who can log in to routers, switches, firewalls, controllers and network automation systems. It is less visible than routing protocols or packet forwarding, but it often becomes the first thing engineers investigate after a password spray, exposed SSH service, failed audit, or unexpected configuration change.

A useful way to think about the management plane is simple: if the data plane carries customer or application traffic, the management plane carries trust. It includes SSH, console access, HTTPS portals, NETCONF/RESTCONF APIs, SNMP, telemetry collectors, AAA servers, backup tools, jump hosts and privileged automation tokens. When this layer is weak, even a perfectly designed BGP, OSPF, EVPN or MPLS network can be changed by the wrong person or the wrong script.

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MPLS L3VPN Basics: VRFs, Route Targets and Provider Core Transport

MPLS L3VPN is one of the classic Service Provider technologies used to carry multiple customer routing tables across a shared provider backbone. It is still a very useful topic to understand because many modern designs, even when they migrate toward Segment Routing or EVPN, keep the same operational ideas: separation at the edge, transport in the core, and policy-driven route import/export.

This updated article uses ready-made diagrams extracted from a PDF source to test how technical images look on Blogger. More importantly, it walks through the basic building blocks of an MPLS L3VPN service: PE routers, CE routers, VRFs, route distinguishers, route targets, MP-BGP, and label-switched transport.

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BGP Route Reflectors: Scaling iBGP with a Simple Test Diagram

BGP route reflectors are one of the most common ways to scale iBGP inside a Service Provider or large enterprise backbone. This short test article is also a technical check: it verifies that the blog automation can publish an article with an embedded diagram and a source line.

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QoS in Service Provider Networks: Design and Operations Guide

QoS in Service Provider networks is not only a voice feature or an old WAN trick. It is a practical control system for deciding which packets should survive congestion, how customer services consume shared infrastructure, and how operators can troubleshoot delay, drops, and jitter without guessing. Modern networks often have plenty of bandwidth, but congestion still appears at handoff links, oversubscribed aggregation, encryption gateways, cloud interconnects, mobile backhaul, and during failures when traffic moves to a smaller backup path.

This article gives a field-oriented QoS design and operations checklist for Service Provider and large enterprise WAN environments. The examples use generic devices and documentation addresses only.

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IS-IS in Service Provider Networks: Design and Operations Guide

IS-IS in Service Provider Networks is still one of the most reliable choices for carrying loopbacks, infrastructure links, MPLS reachability, and Segment Routing information across large backbones. It is quiet, scalable, and protocol-flexible, but it also has a few operational details that can surprise engineers who mostly learned OSPF first.

This guide focuses on practical IS-IS design and operations for provider-style networks: levels, addressing, metrics, authentication, Segment Routing, and the troubleshooting checks that quickly separate a simple adjacency issue from a real control-plane problem.

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EVPN VXLAN Troubleshooting: Common Problems and Fixes

EVPN VXLAN troubleshooting is easier when you stop treating the fabric as one mysterious overlay and start checking it in layers: underlay reachability, BGP EVPN control plane, VXLAN data plane, and tenant routing. Most outages in a data center fabric are not caused by an exotic protocol bug. They are usually caused by a missing route, a mismatched VNI, an anycast gateway inconsistency, an MTU problem, or a route target that does not match the intended tenant.

This guide gives a practical workflow for network engineers operating EVPN/VXLAN fabrics. The commands differ between Cisco, Juniper, Arista, Nokia, FRRouting, and SONiC, but the logic is portable. If you can prove each layer independently, you can isolate most problems quickly without guessing.

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