The main connectivity problem is effective bridging between the Internet and X.25 communities. This presents a particular difficulty as Administrations in different countries make use of different protocols, e.g. the Spanish and German validation sites mainly have X.25 connectivity whilst those in Britain are connected solely via the Internet.
In general national and international connectivity will be provided by using the Internet as the core network. Relay DSAs will be used to link national and X.25 networks and private networks to the core infrastructure.
| DSA DN | Site | Connectivity |
| c=DE, cn=EuroView-DE | Dr. Materna, Dortmund | Internet, X.25 |
| c=ES, cn=EuroView-ES | SEMA Group, Madrid | Internet, X.25 |
| c=GB, cn=EuroView-GB | Brunel University, London | Internet |
Table 5-1. EuroView Backbone DSAs
Each of these DSAs will be second level DSAs, subordinate to first level national DSAs. The relationship between DSAs can be looked at in two ways: protocol map and knowledge model. The protocol map depicts the connectivity of all supra-organizational DSAs that are expected to be accessed by the EuroView service (this does not include slave or backup DSAs).
The EuroView service has been designed to allow for links with DANTE NameFLOW in each country. This requires consideration of national DSAs as well as network infrastructure. Table 5-2 and Figure 5-1 summarize the links involved.
| DSA DN | Masters | Connectivity |
| cn=Puma | c=DE | Internet, X.25 |
| cn=Iguana | c=ES | Internet |
| cn=Inca Dove | c=GB | Internet |
| cn=Rockhopper Penguin | c=AT | Internet |
| cn=Giant Tortoise | ROOT | Internet |
Table 5-2. Higher Level DSAs
Figure 5-1. Protocol Map
All of the EuroView service DSAs have direct Internet connectivity, and indirect International X.25 via the first level national servers of Germany or the Spanish EuroView server. In the case of peer activity, i.e. communication between EuroView, servers the Internet is always used for direct connection.
Cross references will be established between EuroView DSAs to reduce the dependence on the national NameFLOW DSAs.
| Validation Site | Country | Connectivity |
| MAP | Spain | X.25 |
| MAS | Spain | X.25 (via MAP) |
| AA | Germany | X.25 |
| Magistrat Wien | Austria | Internet, X.25 |
| DTI | United Kingdom | Internet |
| CCTA | United Kingdom | Internet |
Table 5-3. Validation Site Connectivity
There is no problem with connectivity in the UK as all validation sites have Internet connectivity. Whilst this is not the case in Germany the situation is alleviated greatly by the fact that the German national DSA has both Internet and X.25 capability. This DSA will relay requests from the Internet to German X.25 sites. Similarly external requests (e.g. from EuroView Internet users in other countries) will be relayed via the national server.
The Spanish sites represent a problem in that user access must be via X.25, whilst the national server does not have the relevant capability. The Spanish EuroView server, situated at SEMA, has both Internet and X.25 and will act as a relay. User DSAs in Spain will use the central DSA as a superior reference (thereby using the EuroView server as a means of accessing the global X.500 service). Conversely the Spanish central DSA will act as a relay and advertise itself as the access point for data held in the user DSAs.
The bi-protocol Sema DSA can equally act as a relay DSA for all EuroView servers, thereby ensuring that data within the EuroView service, be it on a public X.25 or Internet DSA, will be accessible to all EuroView users.