Route Summarisation
Paste prefixes one per line (10.1.0.0/24, 10.1.1.0/24 …). The tool merges adjacent, equal-sized networks into aggregates that cover exactly the input (no extra space), then also shows the single supernet that covers everything, with how much extra address space that would advertise.
Exact aggregates
Addresses in input
Single covering supernet
Extra space if you advertise the supernet
Exact summarySmallest set of prefixes covering exactly the input. Overlapping and duplicate inputs are merged first.
| # | Aggregate | Mask | Addresses | Covers |
|---|
Copy as
How it works
- Each line is normalised to its network address; duplicates and prefixes already inside a larger one are dropped.
- Two networks of the same size whose network addresses differ only in the last network bit are siblings; they’re replaced by their parent (one bit shorter). This repeats until no siblings remain.
- The result is the unique minimal set of prefixes that covers exactly the input. The single covering supernet is the longest prefix shared by all inputs, which is what you’d advertise if you accept some extra space.
Tip
Before advertising an aggregate upstream, make sure every address inside it is really yours. The “Extra space” figure is the amount you’d be claiming without owning.
Last updated on