CESNET2 network topology

The core of the network is formed by a rich DWDM infrastructure with tens of 100, 10, and 1 Gbps transmission channels. We started building the infrastructure in 2005 when we deployed first DWDM circuit connecting Prague and Brno. We have continuously connected further nodes and increased the number of transmission channels and their capacities—the development is based on user demands. We use a combination of commercial devices and optical elements of own design (the CzechLight series). We upgraded the network core to 100 Gbps in 2013.

Other backbone circuits of CESNET2 are based on the 100G, 10G and Gigabit Ethernet and the POS (Packet Over SONET) technology with a rate of 2.5 Gbps. Bandwidth of lines connecting smaller nodes are in the range from 10 Mbps to 1 Gbps. Their capacity has been continuously  increased in accordance with the needs and real traffic through the individual nodes.

The network topology is consists of several rings interconnecting a limited number of cities (optimally less than five cities in a single ring). We aim for a redundant network backbone offering short paths and—in consequence—a low delay introduced by the active network devices.

Network topology

Topologie sítě CESNET

At a network layer the IPv4 and IPv6 protocols are supported. We are able to offer lower-layer and special end-to-end services using dedicated paths (dedicated circuits and networks, lambda services and photonic services).


CESNET2 offers rich international connectivity:

  • Cornerstone is the interconnection with the European GÉANT network with its node located at the CESNET premises. The link capacity is 100 Gbps and it carries mainly the traffic among the academic institutions. Besides the main link, we can use multiple gigabit links to build on-demand international point-to-point paths (end-to-end services).
  • Communication to commodity (commercial) Internet is carried by a line leading directly to the U.S., operated by Telecom Italia. The 10 Gbps bandwidth can be upgraded easily.
  • We have three separated interconnections to national research and education networks in neighboring countries: SANET (Slovakia, 10 Gbps), ACONET (Austria, 10 Gbps) a PIONIER (Poland, 10 Gbps).
  • The 10 Gbps line leading to the NetherLight network (Netherlands) connects us to the GLIF experimental optical network. As our experimental optical network named CzechLight is connected to this link it is not showed on the CESNET2 map.
  • In addition, we possess a separate connenction to the network of Google (10 Gbps).

External interconnections of the CESNET2 network also encompass connections to peering centres:

  • 4×10 Gbps to NIX.CZ, mainly for peering with home Internet providers
  • 10 Gbps to AMS-IX for peering with selected foreign Internet providers

More information

Current traffic volume can be seen on the map of current backbone network load.

Last change: 28.5.2021