Cheddar Network Simulator

See how your network performs before you install it.

Cheddar Network Simulator (CNS) lets you design a network on a map and find out how it will perform before you buy or install anything. You draw the WAN service, router, switches, access points and devices. Cheddar checks the configuration for mistakes, then simulates the traffic packet by packet. It tells you in plain language how browsing, video, calls and other activities will feel, and names the bottleneck.

It's built for people who design and support networks where getting it wrong is expensive: satellite-connected sites, offices, mobile test centers and aircraft cabins.

How it works

1. Draw. Start from a template or a blank map. Drag on the WAN terminal, router, switches, access points and devices, and connect them.
2. Validate. One click checks addressing, VLANs, DHCP, DNS, firewall rules, ports and Wi-Fi, and points you to the item to fix.
3. Simulate. Run the traffic and see how each activity will feel. Change a setting, run again and compare the two runs.

Design the whole network

Everything sits on one map, and each item is set up the way the real equipment is.

Links carry the port and cable type (copper from 100 Mbit/s to 10 Gbit/s, or 1G SFP, 10G SFP+ and 25G SFP28 fiber), access or trunk mode, and VLANs. You can also add cable faults: a break, a cable with only four of eight pins wired, or a damaged cable losing frames.

Import what you already have. Paste an OPNsense config.xml or OpenWrt configuration files to fill in a router's interfaces, DHCP, DNS, routes, firewall rules and shaper, or an access point's radios and SSIDs.

Catch mistakes before you build

Validate checks the design and sorts each finding into an Error (it won't work), a Warning (it works, but probably not as you intend) or a Note. It covers:

• IP addressing, gateways, subnets and DHCP pools
• VLANs, trunks and tagged router interfaces
• DNS, static routes, firewall rules and NAT, including double NAT behind a provider router
• Wi-Fi channels, channel width, load and signal at each device
• Router and switch port counts and port types
• PoE budgets and per-port limits
• Multicast, IGMP snooping and QoS for audio and lighting
• Settings that a specific product doesn't support

Items with problems are marked on the map, and selecting a finding selects the item.

Trace path follows a packet between any two points, link by link, with the VLAN, firewall decision and NAT at each step.

Device console gives every device a command line, so you can troubleshoot the design as you would on site: ping, tracert/traceroute, nslookup/dig, ipconfig/ip addr, route print, arp -a and Wi-Fi status. Windows-style devices answer like a Windows command prompt; Linux devices answer in Linux style. The answers come from the design itself.

Simulate every packet

Cheddar simulates the network packet by packet, not with averages:

• Wi-Fi: shared airtime per channel, collisions and backoff, frame aggregation, PHY rates by standard, width, streams and signal, and retries.
• TCP: connection setup, slow start, congestion control, selective acknowledgments and retransmission timers.
• Switches: per-port output queues sized from the switch's buffer, with strict-priority queuing when QoS is on.
• Router: per-device speed caps, and SQM with FQ-CoDel, CAKE (per-device fairness, and layer cake's priority tin for calls) or a plain FIFO queue.
• WAN: serialization, buffering, delay, jitter and loss. LEO satellite handovers; GEO TCP acceleration, shared upload time slots, rain fade and beam switches; cable upstream grant delay.

Runs are repeatable: the same random seed gives the same result, and a different seed shows how much results vary.

Results in plain language

After each run, Cheddar gives:

• An overall rating: Good, Fair or Poor, with a one-line verdict.
• What users will notice: a rating for each activity, such as web page loads, video pauses, call quality, download speed, responsiveness, audio dropouts, lighting sync and device commands, with the key numbers and the thresholds used.
• Why: the main reasons, such as a full upload link or a busy Wi-Fi channel.
• Who's affected: the devices or groups that did worse than the rest.
• Load on the map: links and access points colored green, amber or red by how busy they were.
• Charts: WAN throughput, queuing delay and Wi-Fi airtime over time.
• Devices table: every device's figures, sortable and filterable.

Print a report on one page, or save it as a PDF. Compare runs side by side: Cheddar marks each activity better, worse or the same, and lists the settings that changed between them.

Satellite and multi-WAN

• LEO presets for OneWeb-class, Starlink-class and Amazon Leo services, including satellite changes where published.
• GEO presets for Inmarsat GX and MCX, modeled the way the network works: TCP acceleration (which doesn't apply to QUIC), upload slots granted by the hub, committed and maximum rates with beam load, and rain fade.
• Events during a run: rain fades, beam switches, satellite switches and WAN outages.
• Multi-WAN: failover by priority or load balancing by weight, with gateway monitoring.
• Redundant routers: VRRP or CARP pairs with shared virtual gateway addresses. Fail the master during a run and watch the backup take over.

Audio, video and lighting

• Audio over IP: AES67 and Dante, including the Powersoft NOTA 142 amplifier, Neutrik DLINE adapters, Dante sources and the Dolby CP950 cinema processor. Cheddar checks AES67 and Dante interoperability, PTP domains, QoS markings, IGMP snooping and Energy Efficient Ethernet, and rates dropouts against each receiver's latency.
• Streaming players: Apple TV 4K and Roku 4K, with video quality from 720p to high-bitrate 4K HDR.
• WLED lighting: controllers with audio-reactive sync, checked so the sync traffic doesn't flood the Wi-Fi.
• Device control: MQTT brokers with topic lists, and HTTP and MQTT commands from local servers, rated on the time from command to action.

Real measurements

• Capture import: load a Wireshark, tcpdump or MikroTik capture. Cheddar measures round trips, loss, speeds, Wi-Fi signal and retries, device delays, video bitrates and audio streams on your computer, and offers to set them on the matching items.
• Measured settings: each device and WAN terminal shows the value the simulation uses, the last measured value and where it came from. You can lock values by hand.
• Device library: save measured devices and reuse them in any project.
• Packet capture out: save a Wireshark file of the WAN port or any device from a simulation run.

Aircraft cabin hardware

• Miltope nMAP2 access points, with the radios set as the hardware has them.
• Innovative Advantage AVDS Node switches, with their card slots, fiber backbone ring and power draw.
• Cabin materials: obstruction losses from measured cabin panels, finishes and passengers, so Wi-Fi coverage reflects what's actually between the access point and the seat.

Routers

• Generic: set up by hand or imported from OPNsense or OpenWrt.
• MikroTik RouterBOARD: hEX (RB750Gr3), hEX S (RB760iGS), L009UiGS-RM, RB5009UG+S+IN and CCR2004-1G-12S+2XS. Choosing a model sets its ports with RouterOS names, and Validate notes RouterOS specifics such as FastTrack bypassing queues.
• SQM: FQ-CoDel, Piece of CAKE, CAKE (layer cake) or FIFO, shaped to a percentage of the WAN rate, with per-device speed tiers and weights.

Save, revise and share

• Every change is saved automatically.
• Save numbered revisions with a note, compare any two, and restore an earlier one.
• Export the network diagram as a PDF (11×17, Letter, A3 or A4), an SVG or a PNG, with an optional load overlay after a simulation.
• Export and import project files to share designs with colleagues.
• Reports and diagrams carry your licensed name.

License tiers

Each license runs for one year. Validate, Trace path and SQM are included in every tier.

System requirements

• Windows 10 or 11 (64-bit), or Linux on x86-64 or ARM64 (for example, a Raspberry Pi 5)
• A current browser: Edge, Chrome or Firefox
• About 10 MB of disk space, plus room for projects
• No installer and no administrator rights

Cheddar runs entirely on your own computer and shows its screens in your browser. Your designs are never sent over the internet.

A note on accuracy

Cheddar is a simulation tool. Its models have been checked against real measurements in certain cases, and WAN presets use published figures or clearly marked estimates. Results give a general picture of where issues may exist, not exact figures. Confirm important decisions on real equipment.