LACP Distribution Calculator
Check how evenly a LAG hash spreads flows across members and how much skew a non-power-of-two bundle causes.
About LACP Distribution Calculator
Hashing maps each flow to one of a fixed number of buckets and buckets to members. When the member count divides the bucket table exactly the split is perfect; otherwise the members holding the leftover buckets run hot, which is the real reason bundles are built in powers of two. Bucket skew is small, but hash-entropy skew is not — a few elephant flows or a MAC-only hash behind a router can put most of the traffic on one member while the bundle reports plenty of spare capacity.
Formulas
LACP Distribution
Buckets per member = floor(buckets ÷ members); the members that absorb the remainder carry one extra bucket, so skew = (busiest buckets ÷ buckets) − (1 ÷ members).
- buckets
- Size of the hardware hash table, typically 256 entries
- remainder
- Buckets left over when members do not divide the table evenly
- skew
- Extra share of traffic the busiest member receives
Flow distribution
flows per member = flows ÷ members, assuming uniform hash input.
Worked example
With the default values below, LACP Distribution Calculator returns Skew on the Busiest Member of 0.130%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Active member linksaccepts 1–32 links
- 6 links
- Concurrent flowsminimum 1 flows
- 5,000 flows
- Hash buckets in hardwareaccepts 8–4,096 buckets
- 256 buckets
- Hash policyone of Source + destination MAC, Source + destination IP, Source + destination IP and port
- Source + destination IP
Results
- Skew on the Busiest Member
- 0.130%
- Hash Buckets per Member
- 42
- Buckets on the Busiest Member
- 43
- Ideal Share per Member
- 16.667%
- Flows per Member
- 833
- Distribution Verdict
- Uneven — 0.13% extra load on 4 member(s); a power-of-two bundle divides cleanly
Step by step
- 1Values used
- 2LACP Distribution
- 3Flow distribution
- 4Skew on the Busiest Member= 0.130
- 5Hash Buckets per Member= 42
- 6Buckets on the Busiest Member= 43
- 7Ideal Share per Member= 16.667
- 8Flows per Member= 833
- 9Distribution Verdict= Uneven — 0.13% extra load on 4 member(s); a power-of-two bundle divides cleanly
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is LACP Distribution calculated?
Buckets per member = floor(buckets ÷ members); the members that absorb the remainder carry one extra bucket, so skew = (busiest buckets ÷ buckets) − (1 ÷ members). Hashing maps each flow to one of a fixed number of buckets and buckets to members. When the member count divides the bucket table exactly the split is perfect; otherwise the members holding the leftover buckets run hot, which is the real reason bundles are built in powers of two.
Why does LACP Distribution matter?
Bucket skew is small, but hash-entropy skew is not — a few elephant flows or a MAC-only hash behind a router can put most of the traffic on one member while the bundle reports plenty of spare capacity.
What values do I need to enter?
This calculator takes 4 inputs: Active member links, Concurrent flows, Hash buckets in hardware, Hash policy. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.