Skip to Content
[CAIDA - Center for Applied Internet Data Analysis logo]
Center for Applied Internet Data Analysis > data : active : ipv4_routed_topology_aslinks_dataset.xml
IPv4 Routed /24 AS Links Dataset

|   Data Sources:    Passive    Active    Other    External   |

IPv4 Routed /24 AS Links Dataset

This dataset is useful for studying the topology of the Internet at the level of Autonomous Systems (ASes), which are approximately network(s) under a single administrative control. ASes are an important abstraction because they are the "unit of routing policy" in the routing system of the global Internet. ASes peer with each other to exchange traffic, and these peering relationships define the high-level global Internet topology. For the purposes of analysis, these peering relationships are represented with an AS graph, where nodes represent ASes and links represent peering relationships.

The IPv4 Routed /24 AS Links dataset provides regular snapshots of AS links derived from the ongoing traceroute-like IP-level topology measurements that make up our IPv4 Routed /24 Topology Dataset. We have collected this IP-level topology data since September 2007 using our next generation Archipelago (Ark) measurement infrastructure. For AS links data prior to September 2007, please see the related Skitter AS Links Dataset (skitter AS links are no longer being collected).

Data from the IPv4 Routed /24 Topology Dataset are processed by using RouteViews BGP data to identify the Autonomous System (AS) associated with each responding IP address and collapsing the original probed IP paths into a set of links between ASes. The process of converting IP addresses into Autonomous Systems involves potential distortion due to:

  • No AS mapping for the IP address: some IP addresses appear in topology probes but are not advertised by any AS;
  • AS Sets: an aggregated set of ASes advertises the prefix;
  • Multi-origin ASes (aka MOASes): several separate ASes advertise the same prefix).

Once IP addresses have been mapped to ASes, two types of AS links can be observed: direct links, in which two adjacent IP addresses map to two different ASes, and indirect links, in which two IP addresses in different ASes are separated by one or more hops for which we could not identify an AS (because some hops were non-responding or because we were not able to identify an AS for the IP address at a given hop). Indirect links are annotated with the size of the gap between ASes as measured in IP hops.

The current AS Links dataset fixes a few bugs in the skitter-based AS-links generation software:

  • The previous generation technique reported the first known link between two ASes, so if both an indirect and a direct link between the ASes was observed, and the indirect link was seen first, only an indirect link between the ASes would be reported. The new version correctly reports direct links.
  • The previous software also reported the first gap size it saw for an indirect link between two ASes. Now, if an indirect link with a smaller gap size is observed, the smaller gap size is reported.

Acceptable Use Agreement

Access to these data is subject to the terms of the following CAIDA Acceptable Use Agreement (printable version in PDF format)

When referencing this data (as required by the AUA), please use:

The IPv4 Routed /24 AS Links Dataset - < dates used >,
Also, please, report your publication to CAIDA.

Data Access

Access the current public CAIDA Ark IPv4 Routed /24 AS Links Dataset (September 2007-present)
Access the archived public CAIDA Skitter AS Links Dataset (January 2000 - February 2008)

Topology Datasets


For more information on Autonomous Systems:

For more information on CAIDA topology measurements, see:

For more information on topology measurements in general see:

  Last Modified: Wed Mar-20-2019 10:11:39 PDT
  Page URL: