AS9505 TWGATE-AP Taiwan Internet Gateway

AS9505 (TWGATE-AP, "Taiwan Internet Gateway") is held by Chunghwa Telecom Co., Ltd., registered to its International Business Group in Taipei. TWGate is Chunghwa's international gateway brand: the AS that carries Taiwan's largest telco's traffic out to the rest of the world, distinct from the domestic HiNet consumer network.

What it's used for

The routing evidence is unambiguous about the role. AS9505 announces only 34 IPv4 prefixes covering roughly 24,576 addresses, plus 10 IPv6 prefixes out of 2001:b200::/32 — a small footprint by carrier standards. But it is observed with around 161 BGP neighbours. That ratio is the classic signature of a wholesale and transit network rather than an access network: an eyeball ISP holding tens of thousands of addresses would peer with a handful of upstreams, not with well over a hundred peers. The addresses here are largely infrastructure and customer-facing gateway space, not a subscriber pool.

Sampled reverse DNS backs this up. Most addresses resolve under twgate-ip.twgate.net in a generated A-B-C-D form, the naming a carrier uses for its own gateway and transit ranges. Notably, the announced space is not purely APNIC: 208.70.200.0/21 and 66.171.112.0/21 are North American blocks, consistent with Chunghwa's overseas points of presence serving trans-Pacific customers from the same AS.

Notable

• Chunghwa Telecom runs several distinct ASes; TWGate is the international/transit face, not the domestic broadband one.
• A few sampled PTRs fall outside the twgate.net pattern (for example a hostname under chtivm.com.tw), consistent with customer and hosted services riding the gateway's address space.