Visibility of IPv4 and IPv6 Prefix Lengths in 2019 vs. 2011

In August 2011, we wrote about IPv4 and IPv6 prefix lengths visible in BGP. That’s just the shape of the distribution though; forgetting about the absolute values and instead viewing the visibility of the prefixes in each prefix length, the v6 space looks like this:

Figure 2: Visibility of IPv6 prefixes in each prefix length

There’s a clear cliff after /48, confirming the commonly accepted maximum length. The IPv4 space looks like this in January 2019:

Figure 4: Visibility of IPv4 prefixes in each prefix length

Of course, in the IPv4 world, unicast prefixes shorter than a /8 don’t really make sense and should not show up in the global routing table (except for 0.0.0.0/0, which some peers share with us).

Source: labs.ripe.net