AG DSN

Arbeitsgemeinschaft Dresdner Studentennetz

Traffic Limit


A traffic limit for connections beyond the Student Network has been agreed upon by us and the TU Dresden IT department (ZIH), to make a connection to the German Research Network (DFN) possible.

Every member with access to the network is provided with 3 GiB of traffic credit each day. This covers incoming as well as outgoing data. However, it is possible to save credit up to 63 GiB. This value results from three weeks of saving (21 days times 3 GiB). Every member starts with a credit of 21 GiB.

You can view your current credit on your traffic page. Additionally, there are plugins available in the Software section, showing the credit directly in the browser.

If you caused more traffic than your credit allowed, your access is blocked until your credit is greater than zero again. This is checked once a day.

Unaccounted networks

All connections within the Student Network and to the networks of the TU Dresden and HTW are not accounted towards your credit. This affects connections to IPv4 adresses of the form 141.30.X.X, 141.56.X.X and 141.76.X.X.

The following addresses are excluded from this exception, to prevent a circumvention of the limit by VPN and tunnels:

  • 141.30.3.50 (vpn.zih.tu-dresden.de)
  • 141.30.3.108 (vpn2.zih.tu-dresden.de)
  • 141.30.4.122 (vpn3.zih.tu-dresden.de)
  • 141.30.61.141 (login2.zih.tu-dresden.de)
  • 141.30.117.36 (obelix.et.tu-dresden.de)
  • 141.76.2.12 (serv12.inf.tu-dresden.de)
  • 141.76.16.140 (login1.zih.tu-dresden.de)
  • 141.76.17.131 (ldap-serv.inf.tu-dresden.de)
  • 141.76.17.143 (ganymed.inf.tu-dresden.de)
  • 141.76.29.146 (vpn1.inf.tu-dresden.de)
  • 141.76.29.147 (vpn2.inf.tu-dresden.de)
  • 141.76.29.148 (vpn.inf.tu-dresden.de)
  • 141.56.15.15 (rob.rz.htw-dresden.de)
  • 141.56.100.248 (rou6.rz.htw-dresden.de)
  • 141.56.100.251 (rou4-outside.rz.htw-dresden.de)

Exceptions for academic work

We can excempt you from the traffic limit if you need larger amounts of data for your academic work, e.g. a thesis in cooperation with a remote research facility.

Please bring a written and signed confirmation from your university supervisor that this is the case, preferably with an end date, such as the deadline for your thesis.

Once the excemption is entered into our system your traffic will still get accounted, but you won't get blocked for negative credit.

Further hints

The time is set up in universal time coordinated (UTC). Therefore, a “new day” begins at 1am in the winter and 2am in the summer. This does not apply at Hochschulstraße. At Hochschulstraße, a "new day" begins at midnigt german local time.

The data is collected every 3 minutes at Hochschulstraße and every 10 minutes at all other buildings. After that period, the traffic page is updated. You should mind this delay if your credit is near zero.

Note that every packet trying to reach or leave your device is counted – even if the packet does not reach its destination, for instance because it is shut down! Usually, this causes an additional accounting of 100KB a day, which should be low enough to be ignored.

A different phenomenon is the usage of Peer-to-Peer applications like EDonkey, Kazaa, BitTorrent etc. These applications flood the network on every single request transmitted, which causes them to be transported to users who:

  • Respond the request partly,
  • Save the IP of the requesting device, to compose requests themselves and
  • to redirect the IP, so other devices can compose requests as well.

Therefore, by using such a program, even after hours of the actual usage, a massive amount of requests is sent to your device, independent of whether it is turned on or off. This can cause many dozens of accounted Megabytes in just a few hours.