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MLAG shares state over a dedicated peer link; EVPN multihoming shares it through BGP

EVPN multihoming vs MLAG on Cumulus Linux: what actually breaks

EVPN multihoming vs MLAG: what actually breaks Both make two leaf switches look like one LACP partner to a dual-homed server. Both forward on both links. So which one holds up when something fails? Two labs on Cumulus Linux, identical wiring, four failure scenarios, every probe accounted for.

11 min read

Active/Active Firewalls the Routing Way: Palo Alto, BGP, and a 3-Second Hold Timer

infiniband verbs banner, hand-drawn excalidraw style: green RNIC chip icon

Skip the Kernel: InfiniBand Verbs in Five Minutes

One Adapter, Many Tenants: InfiniBand Partitions and SR-IOV, From the Firmware to the Wire

Routing Kubernetes into a CLOS fabric with Cilium BGP

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Courses

Fabric lab: build a small cloud, end to end

Build a Cloud-Style Fabric Lab

An 11-part, copy-paste-reproducible build of a small cloud: leaf-spine VXLAN/EVPN fabric, Kubernetes with Cilium BGP, and Active/Active firewalls, all virtual, all on one box.

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Mastering BGP

Mastering BGP delves into its architectural strengths: reliability (TCP foundation, keepalives), stability (MAI, dampening, route refresh), scalability (reflection, confederations, selective propagation), and flexibility (policy-driven, path attributes, communities).

Mastering IS-IS

IS-IS, a robust link-state routing protocol, is key for scalable networks. This series demystifies IS-IS from its Layer 2 operations, NSAP addressing, and hierarchical design to advanced traffic engineering with practical Juniper configurations. Master IS-IS for high-performance network designs.

Network Automation with GO

Hello and welcome to "Network Automation with Go," a blog series designed for network engineers and developers. We'll explore how Go's speed, concurrency, and simplicity can help you build powerful, efficient, and scalable network automation solutions. Get ready to level up your skills!

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FabricSRE part 2: triage, change assurance and the timeline

A DCI link goes down at 18:00. Nexus Dashboard's syslog export lands seven seconds later, the triage turns it into one incident, the investigation names the link, and the fix goes through NDFC with an approval bound to the exact lines a human read. Part 2 of FabricSRE.

10 min read

Nexus 9000 vPC, vPC Fabric Peering and EVPN ESI multihoming: what actually breaks

Three ways to make two Nexus 9000 leaves one LACP partner: vPC, vPC Fabric Peering, EVPN ESI multihoming. All forward on both cables. Which one holds up when a leaf loses the fabric, the host leg dies, or the peer-link goes? Four pairs, one fabric, thirteen drills, three passes.

14 min read

FabricSRE part 1: an SRE agent for Cisco Nexus Dashboard

Nexus Dashboard 4.3.1 exposes enough over its GA API to build a real SRE agent. Part 1: the rules, the fabric twin, a ten-hypothesis investigation with evidence on every line, and the fault harness that proves it names the right failure.

9 min read

Cisco NDFC EVPN Multi-Site with an eBGP underlay: two sites, an ISN, one stretched network, step by step in Nexus Dashboard

Cisco NDFC EVPN Multi-Site with an eBGP underlay, step by step

Build two VXLAN EVPN sites with an NDFC-managed ISN and a stretched subnet in Nexus Dashboard 4.1 using an eBGP Multi-AS underlay. Follow every screen, deployment gotcha, validation step, and the Python automation that rebuilds it end to end.

18 min read

Banner: cisco ndfc vxlan fabric, automated with ansible

Cisco NDFC VXLAN EVPN fabric, automated with Ansible (part 3 of 3)

The same fabric as Part 2, built by one Ansible playbook against the NDFC API: nine stages, every read-back recorded, and the same ping matrix at the end.

6 min read

Banner: cisco ndfc vxlan evpn fabric, step by step

Cisco NDFC VXLAN EVPN fabric, step by step (part 2 of 3)

Create the fabric, discover the switches, pair the leaves, add a VRF and networks, attach the host ports, and prove it with a ping matrix. One NDFC screen at a time.

10 min read

Banner: cisco nexus dashboard 4.3 in eve-ng, step by step, plus a containerlab n9kv fabric for ndfc

Cisco Nexus Dashboard 4.3 in EVE-NG, step by step (part 1 of 3)

Deploy Nexus Dashboard 4.3 as an EVE-NG node, bootstrap it from the console, bring up the cluster, and boot a six-switch N9Kv fabric under containerlab. Every step, with the screen it produces.

9 min read

EVPN multihoming vs MLAG on Cumulus Linux: what actually breaks

11 min read

Cisco Nexus EVPN to Cilium: one request, checkpoint by checkpoint

Where the Packet Died: One Request, Checkpoint by Checkpoint, Across a Nexus EVPN Fabric and Cilium

Your pod is Running, your Service exists, the curl still hangs. Most Kubernetes traffic diagrams stop at a Load Balancer cloud. On bare metal that cloud is a Cisco Nexus EVPN fabric. Here is one HTTPS request traced all the way to the pod, with the command that proves every hop.

6 min read

EVPN MAC Mobility, Watched Live: RFC 7432 Sequence Numbers Across a Cisco and Juniper Multi-DC Fabric

A MAC address leaves a Cisco datacenter and reappears behind a Juniper leaf in another one. Watch RFC 7432 do its job across the multisite DCI: the counter climbing 0, 1, 2, the losing leaf yielding, and the exact BGP packets that carried each move, captured on the interconnect.

8 min read

evpn route types explained from a live fabric

EVPN Route Types: A Deep Dive From a Live Fabric

Type-2 gets all the attention, but a datacenter fabric runs on five core EVPN route types and quietly depends on every one. Here is what each actually carries, decoded from a live multihomed fabric, including the two types MLAG labs never get to show you.

7 min read

Replicating a Two-DC EVPN Datacenter in Containerlab

One git clone, four commands, and 20 minutes later a client curls an anycast VIP by DNS name through two firewalls into whichever datacenter the control plane picked. 39 nodes, zero manual configuration. Here is how the whole lab became a git repo.

6 min read

Testing an Agentic NOC: How to Earn Trust

Part 7 of the Agentic NOC series. How you earn the right to trust a system that watches and sometimes changes your network: 131 offline tests against real captured output, mutated-data fault detection, a live 30-fault campaign, and the worst bug of all, a monitor that mistakes silence for success.

6 min read

A green verified checkmark with the detect-remediate-verify cycle

Results: What the Agentic NOC Actually Does

Part 6 of the Agentic NOC series. Real captured runs: a request crossing both protocol layers to a live switch, the planner fanning out, a 30-fault detect-remediate-verify loop, the monitor self-healing then escalating on a flap and refusing to fake health.

7 min read

Decoding a Two-Datacenter Traceroute, Hop by Hop

A traceroute between two datacenters comes back as six lines. Each one is a precise statement about what a multisite EVPN-VXLAN fabric does to a packet: the anycast gateway, the VXLAN wrap and unwrap, numbered versus unnumbered routers, the crossing between sites. All six, decoded on the boxes.

7 min read

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