AS1

AS1 is the first Autonomous System Number ever issued, and it is currently registered under ARIN to Level 3 Parent, LLC, a Lumen Technologies company. The number was originally assigned to Bolt, Beranek and Newman (BBN), the firm that built and operated the ARPANET's Interface Message Processors and is widely credited as the first Internet backbone, so AS1 carries unusual historical weight. The lineage from BBN to today's holder runs through several acquisitions: BBN's ISP assets went to GTE in 1997, were spun off as Genuity around 2000, and Level 3 Communications acquired Genuity's network assets in February 2003; Level 3 was itself acquired by CenturyLink in 2017 and rebranded Lumen. The key triage point is that the current WHOIS holder is Lumen (Level 3), not BBN, and the BBN/Genuity story is historical heritage rather than a current-operator fact. Today AS1 originates only a small and source-variable amount of address space and is not a primary transit ASN — Lumen's flagship backbone is AS3356. Origination figures differ by source (one tracker shows a very small ~6,144-address footprint with a handful of peers; another shows ~190 prefixes / ~108,000 addresses), so it is best described as small and lightly used. No notable public abuse signal was found as of June 2026; it is effectively a clean, corporate-held legacy/infrastructure ASN.

Operator

Level 3 Parent, LLC (a Lumen Technologies company; ARIN OrgId LPL-141, Monroe, LA) [Confirmed] — ARIN RDAP

Country / RIR

US, ARIN [Confirmed]

Allocated

ARIN ASN RegDate 2001-09-20 (a later registry refresh, NOT the original 1970s–80s BBN assignment, which is unknown at registry level); ASN last updated 2024-06-18 [Confirmed for the shown date; original allocation Unknown]

Org status

active holder (Lumen). Lineage: BBN → GTE (1997) → Genuity (~2000) → Level 3 acquired Genuity network assets (completed 2003-02-04, ~$60M cash + $77M vendor prepayments, per Genuity Form 8-K/SEC) → CenturyLink (2017) → rebranded Lumen [Confirmed]

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-07; largely dormant/infrastructure ASN under a major carrier — bgp.tools

Network & routing

Network type

transit/infrastructure, legacy (lightly used vs Lumen's main backbone AS3356) [Confirmed]

Size

small and source-variable — HE ~6,144 IPv4 addrs (~5 peers) vs another aggregator ~190 IPv4 prefixes / ~108,656 addrs + 3 IPv6; reported as a range — bgp.he.net / bgp.tools (2026-06)

Routing/peering

receives from Lumen AS3356 and others (e.g., Cogent AS174) [Likely]; Lumen operates ROAs (rpki-roa@lumen.com); AS1's own originations minimal (partial/Unknown RPKI)

Notable usage

the first ASN ever issued, originally assigned to BBN (ARPANET IMP operator / first Internet backbone); today a minor Lumen-held legacy ASN — lumen.com

Related ASNs

AS3356 (LEVEL3, Lumen flagship transit), AS3549 (former Global Crossing), plus many other Lumen/Level 3 ASNs [Confirmed for AS3356/AS3549]

Analyst note

Encountered as a historic curiosity and as Lumen-managed infrastructure; WHOIS resolves to Lumen (Level 3), not BBN. Clean legacy ASN.