# germany50-readme.txt
#
# Project: SndLib
#
# Demand matrices from measurements in the German Research Network DFN

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Content:
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1. Origin
2. Creation
3. Format
4. Remarks


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1. Origin
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The dynamic demand matrices contained in the archives
  - directed-germany50-DFN-aggregated-5min-over-1day.tgz            (xml files)
  - directed-germany50-DFN-aggregated-5min-over-1day-native.tgz     (native format files)
  - directed-germany50-DFN-aggregated-1day-over-1month.tgz          (xml files)
  - directed-germany50-DFN-aggregated-1day-over-1month-native.tgz   (native format files)
  - directed-germany50-DFN-aggregated-1month-over-1year.tgz         (xml files)
  - directed-germany50-DFN-aggregated-1month-over-1year-native.tgz  (native format files)
are calculated from real-life accounting data
in the German research network operated by the DFN-Verein
http://www.dfn.de/.

The data is taken and averaged in
   - 5min steps over a day,
   - daily steps over a month, and
   - monthly steps over a year
from measurements in the DFN network in the years 2004 and 2005.

The original data consists of counted Bytes in the considered period
(5min, day, month)

**** NOTICE: THERE MIGHT BE BUGS IN THE DATA, see Remarks ****

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2. Creation
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The original DFN network consists of several hundred locations.
These locations together with the accounting data are confidential.

For this reason and also to provide data for the smaller sndlib networks,
the traffic is aggregated from the DFN locations to the locations
of the germany50 network with 50 nodes
using shortest distances between the original locations and the nodes in the
mentioned sndlib networks.

- The measurement (Byte) values are converted to MBit/s demand values
  and rounded up the 6th decimal place.
- Zero demands are removed, that is, traffic
  with value smaller than 0.0000005 MBit/s is considered to be 0.
- The matrices are meant to be directed (just like the original data),
  that is, there might be traffic between s -> t and also t -> s.
- Loop traffic is already removed, that is, there is no demand between s <-> s

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3. Format
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For the new multiple demand matrix archives we decided NOT to introduce a new XML scheme
nor data format but to use the existing SNDlib formats.
This means that also all the available code (parsing/writing) can be used
for the multiple matrices.

A single demand matrix in the multiple matrices archive is just a Network object without a link section,
that is, it consists of nodes and demands between the nodes. It follows that the Network
parser/writer available in the SNDlib API can be used to parse/write a single demand matrix.
The node sections for all single matrices in the germany50 archives are of course identical and
correspond to the germany50 sndlib network.

In addition to a node and a demand section a single demand matrix also has a Meta-Section
giving additional information about the matrix such as the time stamp, the time horizon,
the origin, and the data unit. The new SNDlib API 1.3 is able to handle this (optional)
Meta-Section.

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4. Remarks
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We do not give any warranty for the correctness of the data.
There might be mistakes already in the original accounting data.
We might also have made mistakes in the creation of the data.