Dear routing-wg, I re-implemented the venerable 'aggregate' tool (by Joe Abley & co) in python under the name of 'aggregate6'. The 'aggregate6' tool is faster and also has IPv6 support. https://github.com/job/aggregate6 Installation is can be done through 'pip', or your operating system's package manager (if they carry the 'aggregate6' tool). $ pip install aggregate6 Example use: $ echo 10.0.0.0/16 10.0.0.0/24 2000::/4 3000::/4 | aggregate6 10.0.0.0/16 2000::/3 Note that 'aggregate6' can also be imported as module in your own python project: >>> import from aggregate6 import aggregate >>> aggregate(["10.0.0.0/8", "10.0.0.0/24"]) ['10.0.0.0/8'] >>> Related to the above example, NTT uses 'aggregate6' as library in their network automation toolchain to help compress firewall rules. When using a dump from the IPv4 Default-Free Zone, it appears that 'aggregate6' can deaggregate that list ~ 50 times faster than 'aggregate'. However the tradeoff is that 'aggregate6' uses a bit more memory. Aggregate6 has been tested with pypy, python2 and python3; and can be used both from the command line and as python module. Aggregate6 is published under the 2-Clause BSD license. Kind regards, Job