https://routeswitchu.com/field-notes/ Lab-first network automation training for working network engineers. en Mon, 31 Aug 2026 00:00:00 GMT https://routeswitchu.com/field-notes/meraki-snmpv1-deprecation/ https://routeswitchu.com/field-notes/meraki-snmpv1-deprecation/ Mon, 31 Aug 2026 00:00:00 GMT Cisco Meraki is dropping SNMPv1 from upcoming MR, MX, and MS firmware, and the two copies of the announcement we received disagree about which MR release does it. Here is what breaks if you ignore the email, why SNMPv2c only postpones the work, and the order to do the migration in. https://routeswitchu.com/field-notes/spanning-tree-short-or-long-path-cost/ https://routeswitchu.com/field-notes/spanning-tree-short-or-long-path-cost/ Sat, 29 Aug 2026 00:00:00 GMT Short path costs come from a 1998 table that runs out of room at 10 Gbps and gives every faster link the same cost of 1, so a single gigabit link can beat three 10 Gbps hops. Long costs fix the arithmetic. Nothing in the protocol notices a network running both methods, because the number on the wire is only a number. https://routeswitchu.com/field-notes/ai-broken-automation-transcript/ https://routeswitchu.com/field-notes/ai-broken-automation-transcript/ Sun, 23 Aug 2026 00:00:00 GMT We asked a coding assistant to turn LLDP neighbor output into a topology diagram. The script exited 0 and produced valid Mermaid, but it drew every cable twice. This transcript includes the returned code, its output, the twelve-line check that reported the duplicate links, and the one-line fix. https://routeswitchu.com/field-notes/fde-postings-mapped-to-network-engineering/ https://routeswitchu.com/field-notes/fde-postings-mapped-to-network-engineering/ Sat, 22 Aug 2026 00:00:00 GMT We compared eight live forward deployed engineer postings with a senior network engineering resume. Network engineers can usually show the customer delivery, travel, troubleshooting, and operational experience these roles require. The missing proof is production software and, for AI roles, LLM systems that were built and evaluated. https://routeswitchu.com/field-notes/turn-lldp-output-into-a-network-diagram/ https://routeswitchu.com/field-notes/turn-lldp-output-into-a-network-diagram/ Sat, 22 Aug 2026 00:00:00 GMT We built a free browser tool that turns show lldp neighbors or show cdp neighbors output into a rendered Mermaid topology diagram. It handles the brief tables and the detail forms, merges duplicate links, and nothing you paste leaves the page. Here is how it handles inconsistent neighbor output, what the diagram cannot show, and what to keep after the first run. https://routeswitchu.com/field-notes/forward-deployed-engineer-network-engineer/ https://routeswitchu.com/field-notes/forward-deployed-engineer-network-engineer/ Thu, 20 Aug 2026 00:00:00 GMT Forward deployed engineers build inside customer environments and stay responsible through production. Network engineers already bring useful production judgment, but they still need to prove they can write, test, and operate software. Here is what current postings ask for and how to build the missing evidence. https://routeswitchu.com/field-notes/can-ai-draw-my-network-diagram/ https://routeswitchu.com/field-notes/can-ai-draw-my-network-diagram/ Tue, 18 Aug 2026 00:00:00 GMT It drafts well and it invents links. The fix is structural. Never ask a model for the picture; ask it for the code that builds the picture from your data, then check the rendered result against the data with a script rather than with your eyes. https://routeswitchu.com/field-notes/diagrams-as-code-vs-drawing-tools/ https://routeswitchu.com/field-notes/diagrams-as-code-vs-drawing-tools/ Tue, 18 Aug 2026 00:00:00 GMT Generated text diagrams stay accurate when the network underneath keeps changing. Drawing tools matter when position on the page carries meaning, or when the diagram only needs to be drawn once for an audience. Most teams need both, and the split is predictable. https://routeswitchu.com/field-notes/generate-network-diagram-from-lldp/ https://routeswitchu.com/field-notes/generate-network-diagram-from-lldp/ Tue, 18 Aug 2026 00:00:00 GMT Collect neighbors with the detail command, normalize each link into a four-field record, deduplicate the two reports of every cable, then print Mermaid. Parsing is where this goes wrong, and it gets most of the space below. https://routeswitchu.com/field-notes/keep-network-diagrams-from-going-stale/ https://routeswitchu.com/field-notes/keep-network-diagrams-from-going-stale/ Tue, 18 Aug 2026 00:00:00 GMT Diagrams go stale because updating them is a separate task from making the change. Generate the diagram from collected state, commit it, and have CI regenerate and compare it, so a drifted diagram fails a check instead of waiting for someone to notice. https://routeswitchu.com/field-notes/mermaid-syntax-for-network-topology/ https://routeswitchu.com/field-notes/mermaid-syntax-for-network-topology/ Tue, 18 Aug 2026 00:00:00 GMT Every piece of Mermaid flowchart syntax a network engineer needs, with the escaping rules, the styling that separates tiers, the renderer differences between GitHub and Obsidian, and the version bug that draws an arrowhead on a link you wrote as undirected. https://routeswitchu.com/field-notes/network-diagrams-as-code/ https://routeswitchu.com/field-notes/network-diagrams-as-code/ Mon, 17 Aug 2026 00:00:00 GMT A working reference for documenting a network in text instead of a drawing tool. The flowchart grammar, the patterns for campus topology, the sequence and state diagrams worth knowing, and the Python that generates the whole thing from LLDP neighbor data. https://routeswitchu.com/field-notes/ccnp-to-netdevops-90-day-plan/ https://routeswitchu.com/field-notes/ccnp-to-netdevops-90-day-plan/ Thu, 13 Aug 2026 00:00:00 GMT For a CCNP-level engineer, this is the bridge from CLI fluency to code: Python through network data, Netmiko, device APIs, Git and CI, and AI you verify. Here is the plan, with a checkpoint you can grade at day 30, 60, and 90. https://routeswitchu.com/field-notes/graded-labs-vs-video-courses/ https://routeswitchu.com/field-notes/graded-labs-vs-video-courses/ Thu, 13 Aug 2026 00:00:00 GMT A video shows someone else configure a device. A graded lab checks your own work and tells you when it fails. Here is a real grading run from one of our labs, the failure included, plus an honest look at where video courses still fit. https://routeswitchu.com/field-notes/network-automation-labs-without-a-home-lab/ https://routeswitchu.com/field-notes/network-automation-labs-without-a-home-lab/ Thu, 13 Aug 2026 00:00:00 GMT We priced five ways to practice network automation, timed our own browser labs with a stopwatch, and wrote down where a home lab still wins. The setup-tax table and the grading transcript are in this note. https://routeswitchu.com/field-notes/what-250-buys-in-network-automation-training/ https://routeswitchu.com/field-notes/what-250-buys-in-network-automation-training/ Thu, 13 Aug 2026 00:00:00 GMT Every price in this note was checked against the vendor's public pricing page on 2026-08-13. The table includes what each option costs at a realistic six-month pace, not the pace the marketing assumes. https://routeswitchu.com/field-notes/ospf-break-fix/ https://routeswitchu.com/field-notes/ospf-break-fix/ Wed, 12 Aug 2026 00:00:00 GMT Three classic OSPF breaks in a four-router lab. An AI agent with CLI access had to find and fix each one. Here is the transcript and the score. https://routeswitchu.com/field-notes/hello-world/ https://routeswitchu.com/field-notes/hello-world/ Sun, 09 Aug 2026 00:00:00 GMT This first note explains what Field Notes is, how every note gets tested before it publishes, and includes one small program that holds us to that standard.