How to read a BGP map

Updated 15 September 2026

A BGP map is a picture of how the rest of the Internet reaches one IP prefix. This guide goes through a live one, the map of 1.1.1.0/24, one part at a time.

Where the routes come from

The routes are collected by RIPE RIS. Its collectors keep BGP sessions with a few hundred networks, called collector peers, and store every route those peers send. Each peer that has a route to the prefix adds one AS path to the map: the list of networks the route went through, ending with the network that announced it. A map seen by 360 peers is built from 360 such paths, and many of them are identical.

Each box is a network

A box stands for one autonomous system (AS), a network with its own routing policy and its own AS number. The first line is the number and the smaller text under it is the name registered for that number. Click a box to open the network's own page, which lists the prefixes it announces.

The arrows point toward the prefix

The collector peers sit in the top row. Arrows run from each of them toward the origin, the green box, and from the origin to the prefix in orange at the bottom. That is the way traffic travels. The routing announcement went the other way round: the origin told its neighbours about the prefix, they passed it on, and eventually it reached the collector.

A box's row is its distance from the origin in AS hops. When paths of different lengths meet, some boxes are moved down a row so that every arrow still points down the page.

The numbers on the lines

The small badge on a line counts the collector peers whose path uses that link. Busy links are drawn thicker and darker, quiet ones thin and pale. The counts grow toward the bottom of the map, because paths that start in different parts of the world join up as they get closer to the prefix.

The red path

The red line is the AS path used by the largest number of collector peers, drawn from its top box down to the prefix, with a red outline on every box along the way. On the map above, 11 of the 366 collector peers use it. It is the most common path among the collectors, and your own traffic may well take another one. Your provider picks from the routes it has according to its own policy, and it often has routes that no collector ever sees.

The colours

• Violet, marked T1 boxes are Tier 1 networks, which reach the whole Internet without buying transit.
• Blue, marked T2 boxes are large national and international transit networks.
• Cyan boxes carry routes for someone else in the paths on this particular map.
• White boxes are edge networks, which only pass on their own routes.

What a map leaves out

To stay readable, a map draws the 12 most used paths and at most five networks per row besides the red path. The legend says how many paths were drawn and how many quieter networks were left out, and the table under the map on the prefix page lists every distinct path. When a network repeats its own number to make a path look longer, a trick called prepending, the number is drawn once.

Some links cannot show up at all. A collector only learns the routes its peers decide to share, and networks usually share their own routes and their customers' routes. A peering link between two networks stays invisible unless one of them passes routes learned over it on to a collector peer.

Reading a map in a minute

1. Find the green box. If there are two, two networks announce the prefix. That happens during a move between providers and in some anycast setups, and it is also what a hijack looks like, so it is worth a second look.
2. Look at the boxes right above the origin. They are its upstreams, and the counts show how the peers split between them. When every path goes through one box, the prefix has a single upstream.
3. Follow the red path up to see how most of the collectors reach the prefix.
4. Check the time in the legend. Routes are from the last 24 hours, and the legend says when RIS last saw them.

Try it on your own network

More guides

• How to find the upstream providers of a networkReading transit providers from AS paths, and what the shares 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.