AS9604 FSI-AS FUJI SOFT INCORPORATED

AS9604 (FSI-AS) is held by Fuji Soft Incorporated (富士ソフト株式会社), a large Yokohama-headquartered Japanese IT services group. Fuji Soft does systems development, integration, cloud and IT-security work for corporate clients, and operates through a set of subsidiaries covering engineering software, data-centre services and software development.

What it's used for

The routing shape says corporate network, not service provider. AS9604 announces just 3 IPv4 prefixes: a /19 (157.120.128.0/19), a /20 and a /21 out of 202.149.0.0, totalling 14,336 addresses, and no IPv6 at all. Crucially it has only one observed BGP neighbour. A network with a single upstream cannot be selling transit and is not peering at exchanges. Combined with a small, static address count that has clearly not grown, this is an enterprise announcing its own space for its own use: internal systems, the company's public-facing services, and the customer-facing infrastructure it runs as part of its integration and managed-service work.

Notable

• Single-homed with three prefixes is about as far from an ISP as a routed AS gets. Whatever Fuji Soft's data-centre subsidiaries sell, this particular AS is not carrying a broad multi-tenant hosting estate at scale.
• The address space is old: 202.149.0.0/20 and 202.149.16.0/21 are early APNIC-era blocks, and the group announces them alongside the 157.120.128.0/19, a legacy class-B-derived range.
• Fuji Soft's own AS should not be confused with those of its subsidiaries or its clients. Card the network in front of you, which is the parent company's.