Is my prefix visible on the Internet?
A prefix can be correctly configured on your router and still be missing from the Internet, or visible from only part of it. A BGP map shows which of the networks that report to the RIPE RIS route collectors can see it, which is the quickest honest answer to "is it announced?".
What "visible" means here
BGP has no central list of announced prefixes. Each network hears routes from its neighbours, applies its own filters and passes on what it accepts. A prefix is visible to a collector peer when a chain of networks from the origin to that peer accepted and forwarded it. The RIPE RIS collectors keep sessions with many such peers, so asking how many of them carry a route for your prefix tells you how far the announcement has spread.
Open the map for the prefix. If the page draws paths, somebody announces it and at least one collector peer receives it. The number printed on each link counts the peers whose path goes that way. A prefix that most peers carry has spread widely. One that only a handful carry has been accepted by a few networks and stopped somewhere. A page that finds no routes means no collector peer has a route for exactly that prefix at the moment.
Read the picture before you change anything
Look at the bottom row first. It should be your origin AS, the network that is supposed to announce the prefix. If a different AS is there, or two origins appear side by side, the problem is not visibility but who announces it, which the guide on spotting a hijack covers. If your origin is there, count the boxes directly above it. Those are your upstreams. A prefix seen through only one of two upstreams you pay for usually means the other session is down, or is not sending the route to the places the collectors sit.
The top row is the collector peers. A wide top row with similar counts means broad visibility. A map where one transit network carries nearly everything and the rest barely appear tells you that your route reaches the Internet through that one network and little else.
Common reasons a prefix is not seen
- It is not originated. The router has no network statement or redistribution for the exact prefix, or the route it should match is missing from the routing table. Check the router before anything else.
- It is too specific. Many networks drop IPv4 prefixes longer than a /24 and IPv6 prefixes longer than a /48 on their borders. This is a widely followed convention rather than a rule in an RFC, but a /25 or a /64 will rarely get far. Announce the covering block instead.
- RPKI says it is invalid. If a ROA exists for the prefix and your origin AS or prefix length does not match it, networks that do route origin validation, described in RFC 6811, drop the route. A ROA that is too strict about the maximum length is a frequent cause after splitting a block. The RPKI validator on PikoNetwork shows the status for a prefix and an origin.
- Your upstream filters by IRR or customer prefix lists. Many providers accept only what your route objects or their own lists allow. A new prefix without a route object may be accepted by nobody. Ask the provider what they filter on.
- The announcement is new. Propagation takes seconds to minutes, and the collectors then need time to record it. If you announced a minute ago, wait before concluding anything.
- The block is reserved. Private, documentation and other special-use ranges are not routed on the public Internet at all.
Partial visibility
The map can show a prefix carried by some collector peers and not others. That points at a filter or a failed session in the middle of the graph, not at your router. Compare a peer that has the route with one that does not and look for the network where the paths diverge. A single upstream that never appears for your prefix, while appearing for your neighbours', is a question for that provider.
Remember what the data cannot show. The collectors see only what their own peers send them, so a network that is not one of their peers is invisible, and a prefix that is reachable only inside a customer cone may never reach them. A missing route on the map is a strong hint, not a verdict. For a single network's own answer use a looking glass, and the guide on BGP map, looking glass or traceroute says which tool answers which question. PikoNetwork also has a looking glass that shows the raw RIPE RIS routes for a prefix.
A short checklist
- Open the map for the exact prefix and confirm your origin AS is the bottom row.
- Note how many collector peers carry it and through which upstreams.
- Check the prefix length against the /24 and /48 convention.
- Check the RPKI status for your origin and prefix, and look at the maximum length in the ROA.
- Check that a route object exists and that your upstream's filters allow it.
- On your own router, confirm the route is advertised to each neighbour.
Try it on a prefix that is widely announced, 1.1.1.0/24, then on one of your own. The difference in the top row is usually the answer. How to read a BGP map explains every element if you are new to the picture.
More guides
- How to read a BGP mapWhat the boxes, arrows, numbers and colours on a map mean.
- 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.
- Origin, upstream and peer: who is who on a BGP mapThe roles networks play on a path, and why peers hide.
- BGP map, looking glass or traceroute: which one to useWhich tool answers which routing question.
- How to spot a BGP hijack on a mapThe signs of a hijack in route data, and the harmless look-alikes.
- BGP visualizers and map tools comparedPath maps, replays, AS explorers and looking glasses, and when to use each.