Autonomous system
AS9378 CABLENET JCOM Co., Ltd.
Residential RIPE
Summary
JCOM Co., Ltd. (CABLENET)
isp residential legacy
AS9378 (CABLENET) is registered to JCOM Co., Ltd. — J:COM, Japan's largest cable operator. The CABLENET handle and the cablenet.ne.jp domain come from a regional Saitama cable company that was folded into the J:COM group through the long consolidation of Japan's CATV industry, and the ASN continues to carry that operation's subscribers.
What it's used for
Pure cable-modem eyeball access. RIS sees 36 IPv4 prefixes but only 45,056 addresses, no IPv6, and exactly one observed BGP neighbour — a stub hanging off a single upstream, almost certainly another J:COM ASN acting as the group backbone. Reverse DNS is uniform and unambiguous: every sampled address resolves to cNNNNNN.netAABBB.cablenet.ne.jp, a mechanical per-customer naming scheme keyed off the address itself. That pattern, spread across many small /20 and /21 blocks from unrelated parent ranges (61.215, 219.124, 180.131, 124.195, 218.45, 202.179, 110.93, 27.113, 103.3), is the fingerprint of a cable operator that grew by acquiring franchises and inherited their address scraps.
Notable
- The high prefix-to-address ratio (36 prefixes for ~45k addresses) is deaggregation, not scale. Many announcements are a /20 alongside the /21s inside it.
- Do not confuse this ASN with J:COM's main network AS9824. Both belong to the same company, but this one is the regional cable-access remnant; the group's larger footprint and peering live elsewhere.
- A single BGP neighbour means there is no redundancy visible at the AS level. This network's reachability depends entirely on its parent.
This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.
Interconnection
Peering at a glance
Internet exchanges
No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.
Transit providers
1 upstream, 0 downstream and 1 adjacent networks observed; most-used upstreams first.
| AS | Network | Paths seen |
|---|---|---|
| AS9824 | JCOM Co., Ltd. | 2,116 |
Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-26, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.
Address space
Summary
IPv4 12 prefixes · 45.06K addresses IPv6 0 prefixes
| Country | Name | Prefixes |
|---|---|---|
| JP | Japan | 12 |
Registry
Allocation record
- Registry
- RIPE
- Handle
AS9378- Registry name
- CABLENET
- Registered
- 1998-08-17
- Last changed
- 2022-02-18
- Allocation
- allocated
Routing security
RPKI and IRR
- RPKI
- 100% valid · 36 valid, 0 with no ROA
- ROAs
- 12 authorising AS9378
- ASPA
- no ASPA record
- IRR
- 100% registered · 36 of 36 announcements
- Route objects
- 36 naming AS9378
Reputation
Classification and threat
Residential Fixed-line consumer ISP. Addresses here are homes.
Spamhaus DROP
Not on ASN-DROP The network as a whole is not listed.
No DROP prefixes None of its announced space is on the DROP prefix list.
Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 446 networks and 1,852 prefixes, as published 2026-10-27. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.
FBI IC3
No IC3 indicators Nothing from the FBI IC3 feed.
IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.
Elsewhere