asn.dev

Observed topology

AS16399 FIRSTCOMM-AS2

Unclassified ARIN

Upstreams 5 carry this network
Downstreams 2 this network carries
Adjacent (IPv4) 8
Adjacent (IPv6) 3
Upstream graph Who carries AS16399, and who carries them, drawn as a map up to the transit-free core. 0 exchanges Where AS16399 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

inferred

Networks observed carrying traffic for AS16399: the AS immediately before it in a routing path. Ranked by how many paths showed the relationship, which reflects how widely it is used, not how much traffic crosses it.

ASNetworkTypeFamiliesPaths seen
AS6461Zayo BandwidthTransitIPv4 IPv6562
AS40264Charter Communications LLCUnclassifiedIPv4386
AS174Cogent Communications, LLCTransitIPv4 IPv6280
AS3356Level 3 Parent, LLCTransitIPv4 IPv6243
AS20473The Constant Company, LLCHostingIPv460

Transit

Downstream networks

inferred

Networks for which AS16399 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS55089THE SEGERDAHL CORP.UnclassifiedIPv460
AS22214Medela IncUnclassifiedIPv446

Adjacency

Adjacent networks

observed

Every AS seen directly next to AS16399 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS6461Zayo BandwidthTransitIPv4 IPv6576
AS40264Charter Communications LLCUnclassifiedIPv4386
AS174Cogent Communications, LLCTransitIPv4 IPv6357
AS3356Level 3 Parent, LLCTransitIPv4 IPv6283
AS20473The Constant Company, LLCHostingIPv460
AS55089THE SEGERDAHL CORP.UnclassifiedIPv460
AS22214Medela IncUnclassifiedIPv446
AS10796Charter Communications IncResidentialIPv425

Provenance

Where this comes from

Derived from routing tables collected at 2026-10-29 10:00 UTC by route-views2,rrc00, as seen from 76 BGP vantage points across 74.36M route entries. These are observations from those vantage points, not a complete or authoritative view of the internet.

Inferred from path position, not from any declaration by either party. A network appearing here is carrying these routes; whether that is a paid transit arrangement, a backup, or something else is not something routing data can tell you. Adjacency is not the same as peering. Being next to each other in a path covers paid transit, settlement-free peering and customer connections alike, and routing data cannot distinguish them. Treat this as "these networks exchange routes", nothing more specific.

Cross-check against RIPEstat or BGP.tools, which observe from a different and larger set of vantage points.