Network and IT Profile

The GSN provides connectivity to the vast majority of schools and administrative units throughout Greece. The services provided by GSN are as follows:

• Basic services: Dial-up access, proxy/cache, web filtering, web page generator, web hosting, portal, e-mail (POP3, IMAP, web mail), forums, news, and instant messenger.

• Advanced services: E-learning tools, video on demand, secure content delivery, real-time services, teleconferencing, and VoIP.

• Infrastructure services: Domain Name System (DNS), directory services (Lightweight Directory Access Protocol [LDAP]), user registration services, statistics, help desk, Geographical Information System (GIS), and remote control (http://www.sch.gr/en/index.php).

The GSN has a traditional, hierarchical design. It does not operate its own backbone but rather leverages the backbone network of the Greek NREN

22. Athanasios Liakopoulos, Kostas Kalevras, and Dimitrios Kalogeras, "Deploying IPv6 Services over Broadband Connections: The Greek School Network Case," http://www.terena.nl/events/ tnc2006/core/getfile.php?file_id=862.

(GRNET; http://www.grnet.gr/en). GSN connects to GRNET via eight POPs over Fast or Gigabit Ethernet links. The distribution layer has 8 primary and 43 secondary nodes, with the equipment being hosted by the national telecommunications operator. The links in the distribution layer have speed ranging from 256 kbps to 5 Mbps and are implemented over ATM, E1, and fractional E1. The distribution layer also hosts nine data centers spread around the country.

Figure 5-7 shows a simplified topology of the GSN, which highlights the backbone and the distribution links. Even if the network continually evolves, as more interconnection links are established or upgraded, the hierarchical topology of the GSN will remain the same.

GSN manages over 13,000 access routers and provides network access over the following media types: dial-up (PSTN or ISDN), ADSL, leased line (SDSL or VDSL), and wireless.

The overall GSN asset distribution is summarized in Table 5-21.

Table 5-21 Greek School Network IT Profile—Assets

Device Type

Number of Devices

Managed workstations and PCs

~80,000

Servers

88

GRNET core routers and switches

90 routers and 32 switches

Access routers

Over 13,000

Unmanaged devices

One per school

The OSs currently deployed in GSN's infrastructure and those it plans to use going forward are listed in Table 5-22.

Table 5-22 Greek School Network IT Profile—Operating Systems

Device Type

Today

Future

PC and workstations

Windows 2003, Windows XP

Windows Vista (from 2007)

Linux

Linux

Solaris

Servers

Windows Server 2003

Windows Server 2008

Routers and switches

Cisco IOS

Cisco IOS

The GSN is actively upgrading its infrastructure to provide higher access bandwidth for schools that can support advanced, media-rich communication. It is also adding or expanding the coverage of new services such as VoIP and content distribution.

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