How to find the upstream providers of a network

Updated 15 September 2026

An upstream provider is a network that carries another network's routes to the rest of the Internet, usually for a fee. Public BGP data shows who does that for almost any AS, provided you keep in mind what the data can see and what it cannot.

Providers, peers and customers

Two networks that exchange routes have one of a few kinds of relationship. A customer pays its provider, and the provider announces the customer's routes to everyone it talks to. Two peers exchange their own routes and their customers' routes, usually without money changing hands, and do not pass what they learn from each other on to their other peers or providers.

None of this is written in the route itself. It has to be worked out from the paths, and for upstreams that works well. In an AS path the network just before the origin is the one that handed the route on. When collector peers all over the world see the route through that network, it is almost certainly selling transit to the origin.

Finding them on BGP Map

1. Open the AS page, for example AS59441. It lists the prefixes the network announced in the last two weeks and draws the map of its largest visible prefix.
2. Read the upstreams table under the map. For each network directly in front of the origin it counts the collector peers that reach the prefix through it.
3. Open two or three more of the network's prefixes from the lists on the same page. Providers are often chosen per prefix, so a network with a backup provider may send one block through each of them.

A prefix page such as 62.60.213.0/24 has the same table next to a second one, transit networks, which counts every network between the collector peer and the origin. That shows the providers of the providers as well.

What the shares tell you

When one network has a share close to 100%, every collector peer reaches the prefix through it, so the prefix has a single upstream. Two networks with large shares usually mean the origin is multihomed and both providers carry the route all the time.

A network with a share of one or two percent is harder to read. It can be a backup provider that most of the Internet ignores while the main link is up, often because the origin prepends its routes toward it. It can also be a network that peers with the origin and happens to share routes with one of the collectors.

Keep in mind that shares count collector peers, not traffic. RIS peers are more common in Europe and among networks that like to share data, so a provider that is strong in another region can look smaller than it is.

From your own router

If your network runs BGP, your routers show the path your own traffic takes: show ip bgp 1.1.1.0/24 on Cisco IOS, show route 1.1.1.0/24 detail on Junos or show route for 1.1.1.0/24 all in BIRD. That is one view from one place. A map puts a few hundred of those views side by side.

Other places to check

• RIPEstat has the same RIS data as tables, with the routing history of a prefix.
• bgp.tools works out upstreams and downstreams from its own route collectors.
• PeeringDB shows where a network peers and its stated peering policy, which helps to tell a peer from a provider.
• The routing registry often has the answer written down. whois -h whois.ripe.net AS59441 returns the network's aut-num object, and many list their providers in import and export lines. Those lines are easy to forget to update, so compare them with the paths.

More guides

• How to read a BGP mapWhat the boxes, arrows, numbers and colours on a map mean.
• Which network announces an IP address?From an address to its prefix and origin AS, and when whois disagrees.
• What is an AS path?How the AS path is written and used, and what prepending does.
• Tier 1 networksThe transit-free networks, with a link to each one's map.