| Passive Data Collections | Data Sources |
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Many types of network measurements involve collecting data
at strategic locations by replicating real traffic en route
to its destination. No additional traffic is introduced
into the network for these measurements; rather, a copy of
all network information passing through a given location is
recorded for future study. Since this type of data
collection does not modify the links it measures, it is
called passive data collection.
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| Active Data Collections | Data Sources |
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Many Internet research projects, including methods of
inferring the available bandwidth of an Internet link or
determining the path connecting two computers, require
introducing specially crafted traffic into the network.
Since these measurements change the overall traffic mix,
they are called active measurements.
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| Realtime Monitors | Data Sources |
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CAIDA operates realtime monitors of network traffic at several
locations. Displays are generally updated within 15 minutes of
collection.
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| Other Data Collections | Data Sources |
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Some data available at CAIDA is neither active nor
passive; these include information facilitating the
mapping of Internet hosts to geographic locations and
a historic cache of Domain Name Service (DNS) hostname
mappings for IP addresses. Also, data derived from
external sources, including the RouteViews data
falls into this category.
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- IPv4 Topology
- IP Address to Hostname Mapping
- Geographic Data
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| External Data Sources | Data Sources |
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Many other organizations house valuable data collections.
CAIDA's Internet Measurement
Data Catalog project will provide a searchable index of
measurements and measurement annotations that can be used to
support research projects. The prototype catalog is expected
to be online in 2005. In addition to the IMDC, we provide links
to several widely-used sources of network data here.
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Cooperative Association for Internet Data Analysis (CAIDA)