Supernet Route Aggregation

📖 Tool Introduction

Route aggregation, also known as supernetting or route summarization, is a core technique in network architecture: when a single router sits behind a dozen /24 networks, announcing them to the upstream as one shorter-prefix route dramatically shrinks the global routing table and speeds up forwarding. This tool makes the whole calculation visual and interactive: you simply paste the CIDR networks you want to summarize, one per line, and the tool automatically finds the smallest and largest network addresses, runs a bitwise XOR to measure their longest common prefix, then aligns the result to the correct network boundary and outputs the final aggregate CIDR. It also shows the netmask, the total number of covered addresses and the original input list for verification. Every computation is pure bit arithmetic, so the result is exact; and because everything runs locally in your browser, no network request is ever made. This matters in real network design: ISPs aggregate customer routes, internal teams summarize pod networks before announcing them to the core, and anyone working with BGP or static routing tables needs to know exactly what single prefix covers a set of subnets without leaving gaps. Doing the bit math by hand, shifting through 32 bits one by one, is slow and error prone, especially when the networks are not neatly aligned to byte boundaries. By feeding all your candidate CIDRs into this tool at once, you get the answer in seconds and can immediately see how much extra address space the aggregate swallows, which helps you decide whether summarizing is worth it or whether you should announce the routes individually. The input order does not matter, so you can paste lists copied straight from a router configuration or an IPAM spreadsheet and the result will be the same every time.

✨ Key Features

• Multi-network input: one CIDR per line with no upper limit; order does not matter
• Longest common prefix: bitwise XOR between min and max networks gives the exact aggregate prefix
• Network-boundary alignment: the result is automatically aligned to the correct network address
• Full statistics: input count, smallest/largest network, netmask and total covered addresses
• Input retained: the result area lists every original CIDR for verification and records
• One-click copy and export: the aggregate route can be copied or saved as a text file

📝 How to Use

1. Type one CIDR per line in the box, for example 192.168.0.0/24
2. Click Aggregate and the tool runs the bitwise calculation automatically
3. Read the aggregate CIDR shown in large type at the top
4. Check the stats grid for smallest network, largest network, mask and address count
5. Click Copy result or Download to reuse the aggregate in your router config

⚠️ Notes

• Format: every entry must be IP/prefix such as 10.0.0.0/16; a bare IP is rejected
• Included space: an aggregate route may cover unused addresses, so watch utilization when planning
• Scattered networks: if the inputs are spread out, the aggregate may be much larger than actual use; filter first manually
• Prefix boundary: the tool aligns the result to the network boundary automatically; no manual alignment needed
• Fully offline: all arithmetic runs locally in the browser with no network request at all