subnet.im

AS21928T-Mobile USA, Inc.

United StatesRegistryARINTypeEyeball

As of 11th November 2026, AS21928 (T-Mobile USA, Inc.), an access network registered in the United States with ARIN, originates 287 IPv4 prefixes covering 14M addresses and 260 IPv6 prefixes. By IPv4 address space that makes it the 52nd-largest of the 80,743 networks we see originating IPv4, and the 17th-largest of 18,754 in the United States. It is seen behind 26 upstream networks, most often AS174 (Cogent Communications, LLC) and AS6461 (Zayo Bandwidth), and in front of 3 downstream networks. Every one of its announcements has a valid RPKI ROA, and none are RPKI-invalid. 38% of its routes reach at least 90% of full-feed peers, and 1 prefix is also originated by another network.

At a glance

IPv4 prefixes

287

IPv6 prefixes

260

IPv4 addresses

14M

IPv6 /64s

77.4B

Upstream graph

The networks AS21928 is seen behind, one and two hops out, drawn from real AS paths.

AS21928Toward the internet core
Upstream graph for AS21928: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS21928T-Mobile USA, Inc.This networkAS174Cogent Communicat…AS3356Lumen (Level 3)AS4637Telstra Internati…AS6461Zayo BandwidthAS6939Hurricane Electri…AS1299Arelion (fka. Tel…AS151326DCConnect Communi…AS3549Lumen (fka. Globa…AS2914NTT America, Inc.AS32590Valve CorporationAS20130Depaul UniversityAS132337Axclusive

Networks observed one and two hops upstream of AS21928 in real AS paths. A thicker line means more vantage points saw that adjacency, so weight tracks how well attested it is — not how much traffic it carries. Adjacency is an observation; whether it is a transit purchase or a settlement-free peering is an inference, and is labelled as one wherever we show it.

Neighbouring networks

122

adjacent networks

Upstreams
2621%
Peers
9376%
Downstreams
32%

Networks carrying this one's traffic toward the rest of the internet.

Upstreams of AS21928
NetworkCountryRelationshipPathsVantage pts
AS174Cogent Communications, LLCUSPeer7,098114
AS6461Zayo BandwidthUSPeer4,586133
AS6939Hurricane Electric LLCUSPeer3,82030
AS3356Lumen (Level 3)USPeer1,841138
AS4637Telstra International LimitedHKPeer1,77712
AS49544i3D.net B.VNLPeer5082
AS14537Continent 8 LLCUSPeer5074
AS7195EdgeUnoCOPeer4844
AS24482SG.GSSGPeer4754
AS58511Swoop (Anycast Global Backbone)AUPeer2732

Prefixes

All 547

The largest blocks AS21928 originates, widest first.

Largest prefixes originated by AS21928
PrefixAddressesVisibility
100.128.0.0/98.4M75/76
162.160.0.0/112.1M75/76
172.32.0.0/112.1M75/76
162.184.0.0/15131k76/76
172.58.0.0/15131k75/76
65.76.0.0/1665.5k76/76
74.60.0.0/1665.5k76/76
162.190.0.0/1665.5k76/76
162.191.0.0/1665.5k76/76
167.20.0.0/1665.5k76/76

Routing health

How AS21928's own announcements validate against RPKI and how far they propagate. The same measures for the whole routing table are on the routing table in numbers.

RPKI origin validation

  • Valid100.0%547
  • Invalid0.0%0
  • No ROA0.0%0

Propagation

  • Globally propagated90% of full-feed peers or more37.8%207
  • Partially propagated40% to 90%36.4%199
  • Seen by few peersUnder 40%25.8%141

Prefix sizes

IPv4 — 287 prefixes

IPv6 — 260 prefixes

  • /2868.7B × /640.4%1
  • /324.3B × /640.4%1
  • /3867.1M × /640.8%2
  • /4016.8M × /6496.5%251
  • /441M × /641.2%3
  • /4865.5k × /640.8%2

Recent changes

Announcements that started or stopped since 12th Oct 2026.

Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.