nanog mailing list archives

Re: aggregate6 - a fast versatile prefix list compressor


From: "Elmar K. Bins" <elmi () 4ever de>
Date: Fri, 1 Dec 2017 11:16:37 +0100

nanog () studio442 com au (Julien Goodwin) wrote:

The first optimisation is to remove any supplied prefixes which are
superfluous because they are already included in another supplied
prefix. For example, 2001:67c:208c:10::/64 would be removed if
2001:67c:208c::/48 was also supplied.

The second optimisation identifies adjacent prefixes that can be
combined under a single, shorter-length prefix. For example,
2001:67c:208c::/48 and 2001:67c:208d::/48 can be combined into the
single prefix 2001:67c:208c::/47. As an IPv4 exampl: 10.0.0.0/24 and
10.0.1.0/24 can be joined into 10.0.0.0/23.

Will it catch cases like:
10.0.0.0/24 10.0.1.0/24 10.0.2.0/23 -> 10.0.0.0/22

I guess the developers will have implemented a loop that runs until no
more optimizations have been found. Which would of course catch it as

Iteration 1
10.0.0.0/24 + 10.0.1.0/24
-> 10.0.0.0/23

Iteration 2
10.0.0.0/23 + 10.0.2.0/23
-> 10.0.0.0/22


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