Supernet / Route Aggregator
Paste any number of IPv4 CIDR prefixes and find the minimal set of covering supernets. Uses the standard binary-trie folding algorithm — the same logic as Cisco IOS aggregate-address and the UNIX aggregate tool.
Input Prefixes
One prefix per line. Comments after # are ignored. Host bits are auto-masked.
Aggregated Prefixes
| # | Supernet | Network Address | Broadcast | Total Addresses | Covered by input? | Coverage % |
|---|
Input Analysis
| Input Prefix | Status | Aggregated Into |
|---|
Single Covering Supernet
The smallest single CIDR block that covers every input prefix. Useful when a single summarised advertisement is required regardless of waste.
What Is Route Aggregation?
Route aggregation (also called route summarisation or supernetting) reduces the number of prefixes advertised in a routing protocol by replacing a group of more-specific routes with a single less-specific covering route. This shrinks routing tables, reduces BGP update churn, and speeds up convergence.
The Binary-Trie Folding Algorithm
Two prefixes of length /n can be merged into a single /(n−1) supernet if and only if they share the same parent: their network addresses are identical in the first n−1 bits, and they differ only in bit n. The algorithm repeatedly scans for such pairs until no more merges are possible.
Common Use Cases
- BGP route summarisation: Replace dozens of more-specific prefixes with one or a few aggregate advertisements using
aggregate-addresson Cisco IOS ornetwork aggregateon Junos. - Firewall ACL reduction: Compress a long list of allowed/blocked CIDRs before deploying to OPNsense, Palo Alto, or Forcepoint address groups.
- OSPF area summarisation: Use
area rangeorsummary-addressto prevent intra-area LSAs from flooding into other areas.