How the simulation decides

• Capacity: a healthy 5G link gives 3 units, 4G and satellite 2, a rural DSL phone line 1.5, a leased line 6. Congestion halves a link (Incumbit keeps 60%, Best Effort Mobile drops to 25%).
• Carriers and plans: the carriers are parodies, not real companies. Incumbit (the old giant: best coverage, highest prices), Asterisk* Mobile (every offer has small print), Best Effort Mobile (cheapest, slowed first when masts are busy), Overhead Space Co. (satellite), Copperfield Telecom (DSL), Trenchcoat Fibre (leased lines) and Avian Carrier Co. (the drone, see RFC 1149). Plans are composites of real German tariff structures: speed caps, data caps that throttle to 0.032 Mbit/s, daily data rations, automatic paid top-ups, introductory prices, setup fees, EU-only roaming and paid priority.
• Money: the budget counts headline prices, as a buyer sees them: €260 a month for a vehicle, €500 a month for the office, €200 for the festival weekend. The score card and calculator show the true cost, including setup fees, price rises, delivery charges and the top-ups your traffic triggered. All prices are illustrative, ex VAT.
• Small print that bites: in the data-hungry missions (broadcast van, office), plans use data as your traffic flows (the van streams 8 Mbit/s for every minute of every match; the office averages about 1.5 Mbit/s through the working day), so capped plans run out on the day the data does, top-ups are counted (up to 40 a month, then the plan is throttled), and daily rations slow to 0.4 Mbit/s until you tap the link to rebook. The ambulance route cuts through Switzerland, where EU-only plans stop working. Priority Boarding plans ignore crowd congestion. Leased lines need a survey, which can add digging costs or delay the line.
• Time-lapse: each mission runs over a real period: a month of match days for the van (8 matches of 2.5 hours), a month on call around the clock for the ambulance, a month of working days (08:00 to 18:00) for the office, and Friday to Sunday (11:00 to midnight) for the festival. Only those hours count. The clock races between problems and slows to real time for each one, so you can watch the switchover. A whole run takes about half a minute; the broadcast van in this prototype takes about a minute.
• Missions: the broadcast van needs 2 units, the ambulance 1.5, the remote office 1.5 and the festival card machines 1, so any single healthy link can do the job. The remote office has weak mobile signal (mobile links carry a quarter less) but can use a phone line or a leased line; the festival crowd leaves every mobile link half full.
• Single line uses your strongest connection only. If it fails, it is offline until that link returns.
• Moving a stream to another link takes 2 seconds off air to re-establish the session. Automatic tactics first wait to be sure the link is really dead, so a short blip never triggers a switch.
• Basic failover uses one connection. When it fails, it waits 1.5 seconds to be sure, then moves the stream to the healthiest remaining link: 3.5 seconds off air in all. A session already running on the backup stays there; once the main link is healthy again, new sessions (the next match, working day, patient journey or card payment) start on it, with no interruption.
• SD-WAN (load balancing) is modelled as typical SD-WAN, as described in the bonding explainer: it measures every link and steers each session to the best one, and it keeps your own background traffic (uploads, updates, syncing) off the link your session uses. A session stays on its link. When that link fails, SD-WAN notices in 0.5 seconds and restarts the session on the healthiest remaining link: 2.5 seconds off air. New sessions always start on whichever link is best at that moment, so SD-WAN moves away from a congested link at the next session; basic failover goes back to its main link even when that link is congested. Some SD-WAN products add packet duplication or their own bonding; those are not modelled here.
• Connection bonding sends every session over every working link at once, through the bonding hub, with 20% overhead. Hub failures are not simulated here (hub redundancy would add a second hub). There is no switchover. When a link drops out, packets in flight are resent over the others: a 0.4-second blip, not a dropped session. Your own background traffic shares the bond, so it still takes some capacity. Quality drops if combined capacity falls below what the mission needs, and the session drops only if every link is down.
• Switching by hand: with any tactic except bonding, tap a connection to move the stream onto it. No waiting to be sure, but still 2 seconds off air while it moves.
• Events: random everyday problems, each hitting one of the networks you picked, chosen at random. The first always hits your strongest link. Outages hit a whole carrier, so two SIMs from one carrier fail together. Some masts are shared, so one problem can take out two carriers. A leased line is far more reliable: most problems aimed at it never happen.
• Catastrophes: one per run, alongside three everyday problems in the hours that count (plus a couple while closed, which nobody notices). Everyday outages last 40 to 55 minutes, crowds about an hour. Each knocks out two of the networks you picked (or your only one) for three hours (the first catastrophe always includes your strongest) and sometimes swamps a third. Problems never overlap, so with three or more networks at least one always survives. With only two, a catastrophe can take out both. Every catastrophe and everyday problem plays once before any repeats.
• Drone delivery: in about 6 runs out of 10, a drone drops off a spare Avian Carrier Co. 4G SIM at a random moment. It is never strong enough to carry the mission alone. Connection bonding adds it to the bond at once. The other tactics only use it if you tap it, because their automatic rules only cover the links they were set up with. It is luck, so it earns no points.
• Score: 800 to start, minus 3 points per minute off air and 0.5 per minute degraded (only in the hours that count), minus 60 per interruption. Up to 100 for network diversity and 100 for a run with no interruptions, so a perfect run scores 1,000.

What it cost you: van €500 a minute off air, at least a minute per drop (sponsor make-goods, illustrative); office 6 people × €45 an hour (Destatis, Germany 2025) for time dropped or breaking up, plus 2 minutes to rejoin per drop; festival €8 per customer who walks off (illustrative); ambulance: no euro figure, readings missed are counted. The comparison replays the same script with the other tactic.

All values are placeholders for sign-off, not measured performance. "Try bonding" replays the same events.