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.
Data Use Terms and Conditions
Acceptable Use Policy for the files of the IPv4 Routed /24 AS Links Dataset
- At the end of the research, or semi-annually (which ever
is more frequent), a summary of the research and any
findings/conclusions will be reported to CAIDA. If any
research is described on the WWW, a URL will be provided.
This information is primarily used in reports to our funding
agencies.
- In so far as possible, research findings and conclusions
using the topology data will be published and/or made publicly
available
- All users who publish a document (including web pages
and papers) using data from the topology data must provide
CAIDA with a copy of the publication.
-
All users who publish a document (including web pages, and papers) using data
from this dataset must cite:
The IPv4 Routed /24 AS Links Dataset - < dates
used >, Young Hyun, Bradley Huffaker, Dan Andersen, Emile Aben,
Matthew Luckie, k claffy, and Colleen Shannon,
http://www.caida.org/data/active/ipv4_routed_topology_aslinks_dataset.xml.
-
Users are encouraged, but not required, to include the following
attribution in the acknowledgments section of their document:
Support for the IPv4 Routed /24 AS Links Dataset is provided
by the National Science Foundation, the US Department of
Homeland Security, the WIDE Project, Cisco Systems, and
CAIDA Members.
-
All users who create a publicly available presentation using
data from this dataset must provide CAIDA with a copy of the
presentation and must use the full name of the dataset ("The
IPv4 Routed /24 AS Links Dataset") in the presentation.
Users are further encouraged, but not required, to include
the URL for the dataset
(http://www.caida.org/data/active/ipv4_routed_topology_aslinks_dataset.xml)
in their presentation.
AS Links Dataset Access
Access the current IPv4 Routed /24 AS Links Dataset (September 2007 - present)
Access the archived Skitter AS Links Dataset (January 2000 - February 2008)
Other Topology Datasets:
- Freely Available Datasets
- Restricted Access Datasets
References
For more information on topology measurements see:
For more information on the Archipelago (Ark) Measurement Infrastructure, see:
Acknowledgments
Special thanks to Matthew Luckie for development of and assistance with scamper.
The AS Links Dataset was sponsored by:
Cooperative Association for Internet Data Analysis (CAIDA)