Free, fast and in your browser. Nothing you paste is uploaded. Built by James Clifford after thirty years of change windows.
34 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 filter mistakes that waste the most time. Every filter tested against Wireshark itself.
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 toolStep-by-step checks for fifteen faults, from the swapped switch you cannot reach to BGP, NAT, policy routing and the ping that only works one way. The command, what healthy looks like, and the usual causes.
Start troubleshooting 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 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 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 library118 switching, BGP, NX-OS, IP services, IPv6 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 libraryCollapsed core, dual-WAN branch, a dual-homed BGP internet edge, firewall transit per VRF, vPC pair and out-of-band management. Diagrams, rules, config and the tests to prove them.
See the designs 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 guide 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 free labsFifteen labs for Packet Tracer, CML or GNS3, from VLANs and trunks to five break-fix tickets, including BGP failover and a TACACS+ lockout. Each ticket ends with a closure note the page checks for you.
Start a lab 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 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 properly180 years of networking on eight strands, from the telegraph to 800G Ethernet, and where they cross, merge and get pruned.
The checks, the rollback rules and the paperwork I use on every Cisco change. It's an 8-page PDF and a Word MOP 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.