AS173

AS173 is a low-numbered Autonomous System Number registered through APNIC to Nippon Telegraph and Telephone Corporation and operated by NTT's Network Innovation Laboratories in Musashino-shi, Tokyo. The AS-name NTTECL-AS and the WHOIS network description "NTT ECL MAPOSnet" preserve the lab's earlier identity as NTT's Electrical Communications Laboratories and its historical association with MAPOS (Multiple Access Protocol over SDH/SONET) research. The key triage point is that this is a research and corporate AS, not one of NTT's commercial transit backbones — PeeringDB classifies it as Educational/Research, and it is operationally distinct from AS2914 (NTT's global IP backbone) and AS2511. Today AS173 originates only two IPv4 prefixes — 163.138.160.0/19 and 192.47.168.0/23, about 8,704 addresses in total — and announces no IPv6. Both originated prefixes are RPKI-valid. It takes transit from two domestic Japanese providers, BIGLOBE (AS2518) and Internet Multifeed (AS7521), and its sole observed downstream is the NTT parent AS2511, so it behaves as an internal/subsidiary AS within the NTT group. Sources differ on the announced-prefix count (RIPEstat reports 2 originated; bgp.he.net shows 7 including cone/transit paths) and on peer counts (8–24 depending on the tracker). No notable public abuse signal was found as of 2026-06-18; the only technical flag is a bgp.he.net bogon-announcement notation worth monitoring.

Operator

Nippon Telegraph and Telephone Corporation, operated by NTT Network Innovation Laboratories (formerly NTT Electrical Communications Laboratories / NTT ECL); APNIC OrgId ORG-NTAT1-AP [Confirmed] — APNIC RDAP (https://rdap.apnic.net/autnum/173)

Country / RIR

Japan (JP), APNIC [Confirmed] — https://rdap.apnic.net/autnum/173

AS name / description

NTTECL-AS; WHOIS description "NTT ECL MAPOSnet" reflecting MAPOS research heritage [Confirmed] — https://bgp.he.net/AS173 , https://bgp.tools/as/173

Org status

active (APNIC status "active"; abuse contact validated 2026-02-26) [Confirmed] — https://rdap.apnic.net/autnum/173

Abuse / contacts

abuse contact rd-it-helpdesk@ml.ntt.com (validated 2026-02-26 per APNIC IRT-NTTECL-JP); physical address 3-9-11 Midori-cho, Musashino-shi, Tokyo

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal as of 2026-06-18 — no Spamhaus ASN-DROP, Emerging Threats, FireHOL, or AbuseIPDB hits, no NANOG escalation found. Sole flag: bgp.he.net notes AS173 announces bogons (routing-hygiene concern, not evidence of malice)

Network & routing

Network type

Educational/Research — internal research network of NTT's Network Innovation Laboratories, not a commercial ISP; distinct from NTT backbone ASes (AS2914, AS2511) [Confirmed] — https://www.peeringdb.com/net/7022

Size / address space

2 originated IPv4 prefixes (163.138.160.0/19 ≈ 8,192 addrs; 192.47.168.0/23 ≈ 512 addrs) totalling 8,704 IPv4 addresses; 0 IPv6. bgp.he.net shows 7 announced (incl. cone/transit) vs RIPEstat 2 originated — reported as a range

[Confirmed for 2 originated] — https://stat.ripe.net/data/routing-status/data.json?resource=AS173 , https://bgp.tools/as/173

Routing / peering

takes transit from BIGLOBE (AS2518) and Internet Multifeed (AS7521); sole downstream AS2511 (NTT parent). Observed peers vary by source (CAIDA 8 / bgp.tools ~24 / A4 15), incl. AS6939, AS9370, AS2518, AS7521. RADB import AS-ANY excluding default; no IPv6 policy [Confirmed for upstreams/downstream; Likely for IRR policy] — https://bgp.tools/as/173 , https://bgp.he.net/AS173 , https://api.asrank.caida.org/v2/graphql

RPKI

both originated prefixes RPKI-valid (ROA-signed), 0 invalid; RIPEstat prefix-level validation was skipped (no prefix supplied) but corroborated by bgp.he.net and bgp.tools [Confirmed] — https://bgp.he.net/AS173 , https://bgp.tools/as/173

IX presence

JPNAP Tokyo (IPv4 210.173.176.33, 100 Mbps port). PeeringDB lists open peering policy, no ratio/contract, regional scope, 20–100 Mbps mostly inbound [Confirmed] — https://www.peeringdb.com/net/7022 , https://bgp.he.net/AS173

CAIDA

AS rank 8,098; clique-member flag set (reflects NTT-group DFZ-clique membership, not AS173 individually being tier-1); customer cone 2 ASNs / 7 prefixes / 50,432 addrs; geo 35.7°N, 139.58°E (Tokyo metro) [Confirmed] — https://api.asrank.caida.org/v2/graphql

Related ASNs

AS2511 (NTT parent, downstream), AS2914 (NTT global IP backbone, separate), AS2518 (BIGLOBE upstream), AS7521 (Internet Multifeed upstream) [Confirmed] — https://bgp.tools/as/173

Registry events

APNIC registration 2008-09-04, last changed 2023-01-11 (RDAP autnum events). Third-party aggregators report an allocation date of 2002-08-01 — a RIR-database artifact, NOT an IEEE-attributed date [Confirmed for RDAP events] — https://rdap.apnic.net/autnum/173 , https://ipinfo.io/AS173

RIS visibility

IPv4 327/327 RIS peers (100%); IPv6 0/323 (no v6). First seen routing 2000-08-18, last seen 2026-06-18 [Confirmed] — https://stat.ripe.net/data/routing-status/data.json?resource=AS173

Analyst note

AS173 is NTT's research/innovation AS (NTTECL / MAPOSnet heritage), NOT Cogent (Cogent is AS174). It is a small, RPKI-clean, internal NTT-group AS. The NTT Communications 2025 breach (~17,891 records) is a separate subsidiary and is not attributed to this network.