asn.dev

Observed topology

AS25512 CDT-AS The Czech Republic

Unclassified RIPE NSP

Upstreams 7 carry this network
Downstreams 24 this network carries
Adjacent (IPv4) 30
Adjacent (IPv6) 17
Upstream graph Who carries AS25512, and who carries them, drawn as a map up to the transit-free core. 1 exchange Where AS25512 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

inferred

Networks observed carrying traffic for AS25512: 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
AS174Cogent Communications, LLCTransitIPv4 IPv6420
AS6939Hurricane Electric LLCTransitIPv4 IPv6123
AS1299Arelion Sweden ABTransitIPv4 IPv681
AS6461Zayo BandwidthTransitIPv4 IPv628
AS1764Next Layer Telekommunikationsdienstleistungs- und Beratungs GmbHUnclassifiedIPv4 IPv612
AS24482SG.GSHostingIPv4 IPv612
AS29504Freenet Liberec, z.s.UnclassifiedIPv4 IPv612

Transit

Downstream networks

All 24

Networks for which AS25512 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS51331SychrovNET s.r.oHostingIPv4 IPv6164
AS43614Economia a.s.HostingIPv4 IPv6149
AS56450Alberon Letohrad s.r.oUnclassifiedIPv4 IPv6134
AS206159Fresh Data s.r.o.UnclassifiedIPv4 IPv691
AS43507RETE internet, s.r.o.ResidentialIPv485
AS200828TERMS a.s.UnclassifiedIPv4 IPv685
AS20609KAZA.cz s.r.o.UnclassifiedIPv478
AS47868AVONET, s.r.o.UnclassifiedIPv4 IPv678
AS51524Ales TesacekUnclassifiedIPv459
AS197550Internet4you.cz, spol. s r.o.UnclassifiedIPv459

All 24 downstreams →

Adjacency

Adjacent networks

All 31

Every AS seen directly next to AS25512 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS1299Arelion Sweden ABTransitIPv4 IPv6957
AS174Cogent Communications, LLCTransitIPv4 IPv6769
AS6939Hurricane Electric LLCTransitIPv4 IPv6311
AS51331SychrovNET s.r.oHostingIPv4 IPv6164
AS43614Economia a.s.HostingIPv4 IPv6149
AS20609KAZA.cz s.r.o.UnclassifiedIPv4135
AS56450Alberon Letohrad s.r.oUnclassifiedIPv4 IPv6134
AS206159Fresh Data s.r.o.UnclassifiedIPv4 IPv691
AS43507RETE internet, s.r.o.ResidentialIPv485
AS200828TERMS a.s.UnclassifiedIPv4 IPv685

All 31 adjacent →

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.