AS9618 — TCN catv-tokushima

Network type: residential

AS9618 announces 2 IPv4 prefixes covering 16,384 addresses and 1 IPv6 prefixes.

About this network

AS9618 (TCN) is held by Cable Television Tokushima (ケーブルテレビ徳島株式会社), known on air as Television Tokushima. It is the largest cable operator in Tokushima Prefecture on Shikoku, and has been a subsidiary of Shikoku Electric Power since 2006. The registry handle catv-tokushima says exactly what it is.

What it's used for

A small regional cable ISP. The AS announces just two IPv4 prefixes, 203.110.96.0/19 and 211.19.160.0/19, for 16,384 addresses in total, plus one IPv6 /32 (2404:2680::/32). The reverse DNS confirms the role directly: sampled addresses come back as usr203110096005.tcn.ne.jp and usr211019176005.tcn.ne.jp, where the usr prefix and the IP encoded straight into the hostname are the standard way a cable operator names its subscriber pool. One sampled address resolves to login.tcn.ne.jp, an operator-side service host rather than a customer line. The single observed BGP neighbour rules out any transit or peering role: this AS sits behind one upstream and exists to give the operator's own cable subscribers addresses.

Notable

• Two clean /19s and nothing else is unusually tidy for a network of this age. Most regional Japanese cable ISPs of comparable size have accreted a dozen or more scattered blocks.
• IPv6 is deployed as a full /32 despite the tiny IPv4 footprint, so the operator's addressing plan has room far beyond its current subscriber base.
• The operator is not independent: it became a subsidiary of Shikoku Electric Power, the regional electric utility, in 2006. The AS is still registered under the cable brand.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy.

Announced prefixes

• 203.110.96.0/19
• 211.19.160.0/19
• 2404:2680::/32

Upstream networks

• AS7522 STNet, Incorporated

Adjacent networks

• AS7522 STNet, Incorporated