AS14363 MTCCOMM

This network announces single addresses to the global routing table, at the bottom of a halving cascade that runs from /25 all the way to /32.

What it's used for

• A regional provider's network. 15,616 addresses across 25 IPv4 prefixes plus 19 IPv6 prefixes, with 25 observed BGP neighbours.

Notable

• Inside 173.233.161.0, the announcements run /25, /26, /27, /28, /29, /30, /31 and then two separate /32s, each starting where the previous one ended.
• The IPv6 side does the same thing in the other direction: 2605:cd40::/47, 2605:cd40:2::/47, then /46, /45, /44, /43, /42, /41, /40 and /39, each twice the size of the last.
• Netnames vary by era: MTCCOMM-NET, MTCCOMM-NET-64-6-0-0-20, NET-74-206-40-0-21, NET-69-161-42-0-23 and MC-3241, all registered to MTC Communications, Inc.
• All eighteen sampled addresses returned a name, every one the address itself with the domain appended: 64.6.2.0.mtccomm.net.

Interesting

• A /32 in the global table is a single host route. Most networks filter prefixes longer than /24, so those announcements are visible to almost nobody, and whatever they were meant to accomplish mostly is not happening.
• Both cascades are the same arithmetic. Splitting a range into every power of two below it is what a tool produces when told to cover an arbitrary start and end with prefixes, so both were almost certainly generated rather than typed.
• Reverse names that are the address plus the domain leave every host sitting four levels deep. It resolves; it just carries no information.
• Twenty-five neighbours for 15,616 addresses is a well-peered small network, which makes the unfilterable announcements more puzzling rather than less.