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The checks, rollback rules and MOP template I use on every Cisco change, free in the Change Window Starter Pack.
Get the free packSomething is broken and you need to find it.
Leave it running while the connection misbehaves. It charts delay and lost requests to Cloudflare, Google and Amazon regions, tells you whether the problem is your connection or further away, tests how the line copes when it is busy, and exports the evidence for your ISP.
Start monitoring free toolStep-by-step checks for twenty faults, from the swapped switch you cannot reach and the slow port to BGP, DMVPN, vPC, WAN failover, NAT and the ping that only works one way. The command, what healthy looks like, and the usual causes.
Start troubleshooting free tool34 real troubleshooting jobs turned into display filters, capture filters and the commands to capture on a Catalyst 9000 or Nexus, plus a checker for the mistakes that waste the most time.
Build a filter free toolPull exactly the lines you need out of show output. Number ranges, whole words and "counter not zero" written for you, with the NX-OS version alongside.
Build a filter free toolIncident updates, supplier requests and change summaries in the order people act on. Paste your own draft and see what will make it land badly.
Write it properlyPlan it, check the numbers, then prove nothing else moved.
Paste show output from before and after a change. See what broke, what moved and what is just expected, worst first, ready for the ticket.
Open the Change Checker free toolSubnets with the config already written, a VLSM planner, summaries that show the space they waste, a wildcard decoder, and IPv6 with EUI-64 and /64 planning.
Open the calculator free toolExact overhead for GRE, IPsec, DMVPN, VXLAN, MPLS and PPPoE, ESP padding included, with the ip mtu, MSS clamp and the ping that proves it.
Work out the MTU free toolTest an AS-path expression against real paths, with the underscore handled the way Cisco handles it, and copy the config for IOS XE, NX-OS or IOS XR.
Open the regex tester free toolA fibre loss budget that tells you which optics will work, copper speed limits, failed test results explained, colour codes, PoE and the UK rules.
Open the cabling guideBreak things where it doesn't matter.
A working global network on a world map: three regions, transatlantic, Suez and transpacific links, OSPF, BGP, LACP and three ISPs, with hosts in London, New York and Singapore pinging all the time. Press the red button, something breaks, and you have thirty minutes to find it with real show commands and fix it.
Break something new free gameThe phone goes at 2am. It's 2am and the clock is running. Pick a CCNA or CCNP ticket, run real show commands and fix it before the duty manager runs out of patience. Animated network, real output, scored on time and method.
Answer the phone new daily puzzleOne broken Cisco config a day. Tap the line that's causing the outage. Three guesses, a hint after each miss, and a streak to keep.
Play today's puzzle free labsTwenty-nine labs for Packet Tracer, CML or GNS3, from VLANs, trunks and port forwarding to OSPF stub areas, PPPoE, QoS on a sub-rate WAN, two-way redistribution, a dual-hub DMVPN, a Nexus vPC pair, three capstone builds (a branch from a blank config, dual-stack OSPF, a small campus with HSRP) and seven break-fix tickets, including BGP failover, a TACACS+ lockout and DHCP snooping. Each ticket ends with a closure note the page checks for you.
Start a labLibraries to read before you need them.
288 switching, routing policy, BGP, multicast, VPN, QoS, data centre, vPC and EVPN, ACI, SD-WAN and SD-Access, ISE and 802.1X, firewall clustering, IP services, IPv6, wireless and cabling mistakes that do something other than you meant, from the trunk that drops every VLAN to the upgrade that rolls itself back overnight. With the fix for each.
Read the gotchas free libraryTwenty-five designs, from the collapsed core, routed access and dual-WAN branch to a Nexus EVPN fabric, EVPN Multi-Site, ACI Multi-Pod, SD-Access, SD-WAN controllers that survive losing a data centre, a three-hub internet overlay with BGP and BFD, a firewall cluster and ISE, plus worked cases from a real brief: a WAN replacement after acquisitions, OT separated from IT, disaster recovery without stretched VLANs, a two-site enterprise with dual ISPs and GRE over IPsec, and routing that follows an active/passive firewall across two EVPN sites. Diagrams, rules, config and the tests to prove them.
See the designs new free libraryNineteen techniques you never think you will need until the day you do: one source out of one ISP and everything else out of the other, a prefix announced only when the primary dies, BGP policy that changes with the time of day, NAT between two VRFs, draining BGP before maintenance. Each with the config and the trap.
Read the tricks field notesShort answers to the questions engineers keep asking, from thirty years of Cisco networks. Starting with ACLs, route-maps and distribute-lists.
Read the notes interactive timeline180 years of networking on eight strands, from the telegraph to 800G Ethernet, and where they cross, merge and get pruned.
Explore the historyThe checks, the rollback rules and the paperwork I use on every Cisco change. It's a 10-page PDF and a Word MOP (method of procedure) template, and it's free.
The MOP Builder writes the method of procedure, the change board wording and the rollback for ten common Cisco changes across IOS XE, NX-OS and IOS XR.