Calculate supernets by aggregating multiple contiguous subnets into a single larger network (route summarization).
Paste a list of subnet prefixes and the tool tests whether they collapse into one larger block. Each prefix becomes an address range; the tool joins them and checks that the union is one continuous interval whose size is a power of two, starting on an address aligned to that size. If so, it returns the summarizing prefix with mask, address range, usable host count, and a routing-table line. Otherwise it reports the set as not aggregable. The usual surprise: contiguity alone is not enough, so adjacent /24s such as 192.168.1.0 and 192.168.2.0 cannot be merged at all.
A concrete input and expected output from the current implementation.
Input
192.168.8.0/24 192.168.9.0/24 192.168.10.0/24 192.168.11.0/24
Expected output
192.168.8.0/22 Netmask: 255.255.252.0 Range: 192.168.8.0 - 192.168.11.255 Addresses: 1024 (1022 usable)
Four /24 blocks hold 4 x 256 = 1024 addresses, exactly the size of a /22 (2^10). The starting address 192.168.8.0 sits on a 1024-address boundary because the third octet 8 is a multiple of 4, so the merged block is exact: it covers all four inputs and spills into neither 192.168.7.255 nor 192.168.12.0.
Each prefix is expanded to a numeric start and end address by applying its mask. The tool sorts the ranges, looks for gaps and overlaps, and if the union is one continuous interval, verifies that its size is a power of two and that the first address is divisible by that size. A prefix that breaks the run means the set is not aggregable as typed.
For N equal-length prefixes of length P, the summary length is P minus log2(N): two /24s become a /23, eight become a /21. The output gives the network address, mask in dotted decimal and CIDR form, the address range, usable host count, and a routing-table line. Inputs of mixed lengths are summarized as the smallest set of covering blocks that exactly matches them.
Not exactly. CIDR is the addressing scheme that lets a prefix have any length; supernetting is the aggregation practice that motivated it, replacing several longer prefixes with one shorter one. The same notation serves both: subnetting cuts a block into smaller pieces, supernetting joins adjacent pieces back into a bigger block. The result of a successful merge here is a CIDR block, just one with a shorter prefix.
No. A single prefix describes one continuous interval, and 10.1.0.0 and 192.168.1.0 differ in the very first bit, so the smallest block covering both is 0.0.0.0/0, the entire IPv4 space. The tool reports them as not aggregable; summarization only works within a continuous range you control.
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