What will limit service at the event?
Check the radio and backhaul limits against the demand forecast.
The question
You plan downlink capacity for a US venue. The same traffic group uses the radio and the backhaul link that carries traffic back to the network. The capacity owner approves changes to the plan.
| Mb/s | |
|---|---|
| Usable radio limit | 1400 |
| Usable backhaul limit | 1200 |
| Forecast demand | 960 |
Use the smaller link limit. Keep 15% of usable path capacity free. All figures cover the same hour and direction.
“Does the forecast fit, and which link limits the plan?”
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A strong answer, step by step
Open each step in turn. This is one strong answer, not the only one.
Step 1: Find the binding limit
What would you do here? Open the move you’d make.
Use the 1,200 Mb/s backhaul limit and keep 15% free.
The strong move. The same traffic crosses both links. The smaller usable limit sets the path capacity.
Add the two link limits to get 2,600 Mb/s.
Tempting, but it misses something. Every bit uses both links. Their capacity cannot be added for this traffic group.
See how a strong candidate says it
“Backhaul limits the path to 1,200 Mb/s. With 15% held free, the planning ceiling for demand is 1,020 Mb/s.”
Why it works: The same traffic crosses both links. The smaller usable limit sets the path capacity.
Step 2: Check the first forecast
What would you do here? Open the move you’d make.
Report 80% utilization and 60 Mb/s below the ceiling.
The strong move. The 15% rule is already accounted for in the 1,020 Mb/s planning ceiling.
Report 240 Mb/s available for new demand within the plan.
Tempting, but it misses something. 240 Mb/s is the physical spare. The plan needs 180 Mb/s of it to stay free.
See how a strong candidate says it
“960 Mb/s uses 80% of the path and leaves 60 Mb/s below the planning ceiling. I’d record the time and keep the forecast with the link record.”
Why it works: The 15% rule is already accounted for in the 1,020 Mb/s planning ceiling.
Step 3: Recalculate peak demand
The revised event forecast is 1,120 Mb/s for the same busy hour. One option adds 300 Mb/s of radio. The other raises backhaul to 1,400 Mb/s before the event if the capacity owner accepts the contracted link.
What would you do here? Open the move you’d make.
Use the temporary backhaul option, subject to acceptance.
The strong move. The temporary backhaul raises the lower limit to match the existing radio limit.
Add radio capacity and keep the current backhaul.
Tempting, but it misses something. The current backhaul still limits the path to 1,200 Mb/s, with a 1,020 Mb/s planning ceiling.
See how a strong candidate says it
“1,120 Mb/s is 100 Mb/s over the current ceiling. Extra radio leaves the backhaul limit unchanged. With the temporary backhaul, the path would have a 1,190 Mb/s planning ceiling and 70 Mb/s below it.”
Why it works: The temporary backhaul raises the lower limit to match the existing radio limit.
Step 4: Give a conditional plan
What would you do here? Open the move you’d make.
Give the team the revised forecast and the owner’s acceptance check.
The strong move. The plan keeps the capacity condition and the next decision with the owner.
Give service staff an unconditional capacity promise now.
Tempting, but it misses something. The contracted link still needs acceptance. The current path misses the planning floor for spare capacity.
See how a strong candidate says it
“I’d recommend the backhaul option and ask the owner to confirm acceptance before the event. Then the forecast uses 80% of the path, with 280 Mb/s of physical spare. I’d reopen the plan if demand or acceptance changes.”
Why it works: The plan keeps the capacity condition and the next decision with the owner.
The answer, in short
- Decision
- Recommend the temporary backhaul option, subject to the owner’s acceptance.
- Because
- The revised path has a 1,190 Mb/s planning ceiling against 1,120 Mb/s of demand.
- What would change it
- A different forecast or a delayed acceptance changes the capacity plan.
Common traps
- Adding links that carry the same traffic.
- Counting reserved capacity as available for new demand.
Check your answer
- I found the binding limit.
- I kept the spare-capacity rule.
- I checked both options.
- I gave the owner an acceptance condition.
Last reviewed Nov 11, 2026