GRNET Backbone network (IP & Carrier)

The interconnection needs of GRNET organizations refer to the:

  • Connectivity with the GRNET IP network, wherefrom they can exchange traffic with each other and with the rest of the (Greek and international) internet and have access to the computing / storage services of GRNET.
  • Private Networks (VPN) setup:
  • between the points of presence of an organization, for the exchange of internal traffic,
  • between two or more GRNET organizations, in the context of a collaboration, research project or experiment,
  • between GRNET organizations and organizations of other European academic networks, in the context of a collaboration, research project or experiment,
  • between an organization and GRNET datacenters, in the context of GRNET service (e.g. for the integration of some virtual machines in the organizations’ s internal network).

The ideal networks can be created through various methods, such as L2 / L3 VPNs, dedicated optical « λ» wavelengths (lambdas) in the optical network, dedicated circuits, etc.

The interface that is used for the organization’s interconnection to the GRNET network is always of an Ethernet type. The connection speed for organizations that are “on” the GRNET private owned network is typically 1Gbps, while a number of advanced organizations are connected at 10Gbps. Organizations outside the GRNET optical network, typically use lower speed metro ethernet circuits. Finally, there is a limited number of organizations accesses that are implemented through self-owned fibers, wireless networks, or other technologies.

General Architecture

The GRNET network architecture defines three distinct layers of service:

  • the optical service layer, provided by the GRNET optical network (optical equipment and fiber optic network) for physical interconnection services.
  • the carrier service layer, provided by the Carrier network and the GRNET access network for Ethernet interconnection services.
  • the IP service layer, provided by the GRNET IP network for IP interconnection between GRNET organizations, its data nodes, the Greek and International Internet.

Carrier and Access Networks

Visual Services Layer

The optical service layer provides physical interface services. Services are provided either directly over optical fibers or multiplexed via GRNET DWDM/CWDM equipment.

Carrier Service Layer

The carrier service layer provides Ethernet framing services, mainly between the GRNET IP network, its data centers and its organizations. Services are provided jointly by the Carrier Network (CN) and the Access Network (AN). Both the Carrier network and the access network rely on the physical interconnection services of the optical network, which provides circuits either directly over “dark” optical fibers, or multiplexed via GRNET DWDM / CWDM equipment.

Types of interconnection services provided at the carrier service layer

    • E-Line: providing two-way Ethernet connection between two end points.
    • E-LAN: providing two-way Ethernet connection among more (> 2) end points.
    • E-Tree: provides a two-way Ethernet connection between a single root- point and multiple end points – leafs without direct communication between the leaves.

    Each of the above services may be terminated, at any end point, at a physical port level (“private Ethernet connections”) or at the VLAN level (“virtual private Ethernet connections”).

Typical usage scenarios

    • Connections of organizations to the GRNET IP network: these include E-LINE services between the organizations points of presence (PoP) and the GRNET IP network. Through these connections the organizations IP equipment is connected to the GRNET IP equipment in order to exchange the IP traffic. Multiple connections between different GRNET routers and the organization (at the same or different point of presence) can be used to protect the routing (e.g setting up different BGP – BGP sessions).
    • VPNs of organizations with the GRNET data centers: these include E-LINE or E-LAN ​​services, which aim to connect at level 2 (Ethernet) the organization’s infrastructure to GRNET services that are provided inside the data centers. A typical example of such services are the virtual machines that GRNET provides in its central infrastructure to the organizations, where they implement their internal or public services.
    • VPNs between organizations: these include E-LINE or E-LAN ​​services, which are used to interconnect at level 2 (Ethernet) the points of presence of an organization or multiple organizations with each other. Of particular interest is the case of 802.1ad VPNs, where all Ethernet frames are transferred between two or more physical ports ending there, regardless of their 802.1q tags and without requiring any special handling per tag by GRNET.


    • Connection of data and services centers to GRNET IP network: these include E-LINE services setting up IP connections between the data center equipment and the GRNET IP equipment.