asn.dev

Observed topology

AS8251 NFX_ZSPO

Upstreams 8 carry this network
Downstreams 16 this network carries
Adjacent (IPv4) 24
Adjacent (IPv6) 18

Transit

Upstream networks

inferred

Networks observed carrying traffic for AS8251: 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
AS1299Arelion Sweden ABTransitIPv4 IPv6244
AS6939Hurricane Electric LLCTransitIPv4 IPv675
AS29208Quantcom, a.s.UnclassifiedIPv4 IPv649
AS16019Vodafone Czech Republic a.s.UnclassifiedIPv412
AS24482SG.GSHostingIPv4 IPv67
AS29504Freenet Liberec, z.s.UnclassifiedIPv4 IPv67
AS57463NetIX Communications JSCUnclassifiedIPv46
AS202297Skylon Solutions LimitedUnclassifiedIPv46

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.

Transit

Downstream networks

inferred

Networks for which AS8251 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS57707Greendata s.r.o.HostingIPv4 IPv6424
AS34596HVfree.net servis. s.r.o.UnclassifiedIPv4 IPv6217
AS201608HovNet-SERVIS s.r.o.UnclassifiedIPv4 IPv6217
AS198813SychrovNET s.r.oUnclassifiedIPv4 IPv6199
AS49095PRAHA12.com s.r.o.UnclassifiedIPv4 IPv6158
AS41670hkfree.org z.s.UnclassifiedIPv4 IPv6158
AS198977UnArtel s.r.o.UnclassifiedIPv4 IPv6157
AS59984KLFREE NETWORKS, s.r.o.UnclassifiedIPv4 IPv6108
AS12984PilsFree, z. s.UnclassifiedIPv4 IPv695
AS214224CeskaSit.net Networks s.r.o.UnclassifiedIPv461
AS51400SPOJE.NET s.r.o.UnclassifiedIPv4 IPv660
AS51331SychrovNET s.r.oHostingIPv447
AS196843KHnet.info, z.s.UnclassifiedIPv432
AS62099JM-Networks, s.r.o.UnclassifiedIPv432
AS31349a-net Liberec s.r.o.ResidentialIPv611
AS59747NIX.CZ z.s.p.o.UnclassifiedIPv64

Adjacency

Adjacent networks

42 shown

Every AS seen directly next to AS8251 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS1299Arelion Sweden ABTransitIPv4 IPv61,816
AS49095PRAHA12.com s.r.o.UnclassifiedIPv4 IPv6661
AS6939Hurricane Electric LLCTransitIPv4 IPv6636
AS57707Greendata s.r.o.HostingIPv4 IPv6564
AS29208Quantcom, a.s.UnclassifiedIPv4 IPv6467
AS198813SychrovNET s.r.oUnclassifiedIPv4 IPv6314
AS34596HVfree.net servis. s.r.o.UnclassifiedIPv4 IPv6217
AS201608HovNet-SERVIS s.r.o.UnclassifiedIPv4 IPv6217
AS12984PilsFree, z. s.UnclassifiedIPv4 IPv6190
AS41670hkfree.org z.s.UnclassifiedIPv4 IPv6158
AS198977UnArtel s.r.o.UnclassifiedIPv4 IPv6157
AS16019Vodafone Czech Republic a.s.UnclassifiedIPv4112
AS59984KLFREE NETWORKS, s.r.o.UnclassifiedIPv4 IPv6108
AS214224CeskaSit.net Networks s.r.o.UnclassifiedIPv461
AS51400SPOJE.NET s.r.o.UnclassifiedIPv4 IPv660
AS29504Freenet Liberec, z.s.UnclassifiedIPv4 IPv660
AS24482SG.GSHostingIPv4 IPv660
AS51331SychrovNET s.r.oHostingIPv447
AS202297Skylon Solutions LimitedUnclassifiedIPv447
AS57463NetIX Communications JSCUnclassifiedIPv443
AS62099JM-Networks, s.r.o.UnclassifiedIPv432
AS196843KHnet.info, z.s.UnclassifiedIPv432
AS59747NIX.CZ z.s.p.o.UnclassifiedIPv4 IPv619
AS8218Zayo Infrastructure France SAUnclassifiedIPv4 IPv613
AS31349a-net Liberec s.r.o.ResidentialIPv611

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.

Interconnection

Exchange presence

recorded

Internet exchanges where Packet Clearing House has a port recorded for AS8251, largest fabric first. An exchange is shared switching where networks interconnect directly rather than paying a transit provider to carry traffic between them, so turning up at one is a deliberate choice about how this network wants to be reached. Each name opens that exchange's own page, with its peering LANs and every other network recorded on it.

No exchange membership on file. That is not the same as peering nowhere: the dataset records what PCH has collected, and many exchanges publish no participant list at all.

Unlike the tables above, this is recorded rather than inferred. An address on a peering LAN is at that exchange by definition. Two carve-outs all the same. Member ports counts every participant at the exchange, not this network's ports, so read it as a size proxy. And an absent exchange means PCH has no record of it, not that the network is not there.

Provenance

Where this comes from

Derived from routing tables collected at 2026-08-08 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 74.02M route entries. These are observations from those vantage points, not a complete or authoritative view of the internet.

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

Exchange presence comes from a separate dataset: the directory collected 2026-08-08 by Packet Clearing House (https://www.pch.net/ixp/data), covering 1,327 exchanges and 93,137 recorded member ports, licensed CC BY-NC-SA 3.0.

PeeringDB is the better-known directory and is deliberately not the source here: its acceptable-use policy forbids the bulk storage this needs. The two answer different questions anyway. PeeringDB reports what an operator declares about itself; this reports what PCH has recorded.