HOW IT WORKS
Summarize IP ranges without adding addresses
Networks are sorted, then overlapping, contained and adjacent ranges are combined. Each merged range is decomposed into aligned CIDR blocks to produce an exact minimal list.
The four /24s from 192.168.0.0 to 192.168.3.0 combine into 192.168.0.0/22. If there is a gap, the output does not include that gap merely to make a broader summary.
Before summarizing actual routes, verify next hops, routing policies and possible black holes during failures. Address arithmetic alone does not establish whether a summary is safe to deploy.