Autonomous system detail

AS91

Announced

Operated by RPI-AS - Rensselaer Polytechnic Institute.

Summary

// analyst note
A stable R&E network; clean. Actively announcing 12 IPv4 prefixes (~330k IPs) and 2 IPv6 prefixes, including its historic /16s. Original ARIN ASNumber-record RegDate is 1986-11-18 (the IPinfo 0000-00-00 was a placeholder, not a real date).
// security note
NEUTRAL/DATED: no notable public abuse signal found as of 2026-06-08; clean R&E network.
IPv4 prefixes
12
~330.5K addresses
IPv6 prefixes
2
announced
Peer networks
5
5 up · 0 down
IANA block
1-1876
Assigned by ARIN
[ 01 ] — Context

About this ASN.

Updated  ·  Confidence: High

AS91 is a legacy allocation registered under ARIN to Rensselaer Polytechnic Institute (Troy, NY), carrying the handle "RPI-AS" — the same label RFC 1020 (1987) recorded, held since the 1980s. It is RPI's campus AS, and it announces considerably more than its two best-known Class B blocks: RIPEstat routing-status reports 12 IPv4 prefixes (roughly 330,000 addresses) and 2 IPv6 prefixes, fully visible (327 of 327 IPv4 and 322 of 323 IPv6 RIS peers) with 5 observed neighbours. The IPv4 set includes the historic /16s 128.113.0.0/16 and 129.161.0.0/16 plus additional /16s (128.213.0.0/16, 129.5.0.0/16, 146.8.0.0/16) and several smaller 192.12.91–92.0/24 and 204.76/204.145 ranges; the two IPv6 prefixes are 2620:0:bf0::/48 and 2620:0:2820::/48. The abuse contact is security@rpi.edu. The ARIN ASNumber-record RegDate is 1986-11-18, confirming an original mid-1980s allocation. For triage this is a stable research-and-education network, clean and actively announcing. No notable public abuse signal was found as of June 2026.

Operator
Rensselaer Polytechnic Institute (Troy, NY) [Confirmed] — ARIN RDAP / IPinfo
Country / RIR
US, ARIN [Confirmed]
Allocated
1986-11-18 (ARIN ASNumber-record RegDate) [Confirmed] — RIPEstat whois / ARIN RDAP
Org status
active

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-08; clean R&E network — ipinfo.io

Network & routing

Network type
research / education [Confirmed]
Size
12 IPv4 prefixes (~330,496 IPs) + 2 IPv6 prefixes; fully visible (327/327 v4, 322/323 v6 RIS peers) [Confirmed] — RIPEstat routing-status (2026-06-19)
Routing/peering
actively announcing; 5 observed neighbours; abuse contact security@rpi.edu; RPKI unknown — RIPEstat
Notable usage
[historical/current, RFC 1020] AS91 "RPI-AS" — RPI's campus AS, held since the 1980s; announces 128.113.0.0/16, 129.161.0.0/16, 128.213.0.0/16, 129.5.0.0/16, 146.8.0.0/16 and smaller blocks, plus IPv6 2620:0:bf0::/48 and 2620:0:2820::/48 — rpi.edu
Related ASNs
none specifically confirmed for this profile
Analyst note
A stable R&E network; clean. Actively announcing 12 IPv4 prefixes (~330k IPs) and 2 IPv6 prefixes, including its historic /16s 128.113.0.0/16 and 129.161.0.0/16. Original ARIN RegDate 1986-11-18.
[ 02 ] — Announced prefixes

What this network routes.

14 prefixes total · RIPEstat data · cached, not real-time
// IPv4 prefixes12
  1. 128.113.0.0/16/16
  2. 146.8.0.0/16/16
  3. 129.161.0.0/16/16
  4. 128.213.0.0/16/16
  5. 129.5.0.0/16/16
  6. 204.76.224.0/22/22
  7. 204.76.228.0/23/23
  8. 192.12.91.0/24/24
  9. 204.76.223.0/24/24
  10. 204.145.205.0/24/24
  11. 192.12.92.0/24/24
  12. 204.76.222.0/24/24
// IPv6 prefixes2
  1. 2620:0:2820::/48/48
  2. 2620:0:bf0::/48/48
[ 03 ] — Notable peers & upstreams

Who it talks to.

5 observed neighbours
// Notable connectionsTop 5 of 5
ASNOperatorRole
AS174 — upstream
AS13536 — upstream
AS3356 — upstream
AS3754 — upstream
AS3630 — upstream
Neighbours observed via public BGP collectors; not a complete peering list.