This is the most external zone of the CDCs (Central of Data and Contents). Its function is to provide connectivity to/from the outside.

From this zone, all lines of communications start their rout (to clients and to other InterHost central nodes) as well as diverse accesses to IP traffic suppliers (ISP - Internet Service Provider).

All different service networks begin at this zone.

These routers' function consists in providing Internet entrance and exit connections, exchanging traffic with the IP traffic suppliers and with the different InterHost centers and nodes.

In order to provide redundancy, each CDC is equipped with more than one provider of transit to the Internet, and the politics of InterHost are based on the access' suppliers diversification. This enables us to offer the advantages of a host independent of carrier, us being able to select the road by which we will direct a determined "dispatch". We negotiate our own routing politics.

InterHost is autonomous system; our backbone routers contain the boards of all Internet routes.

The employed technology is: two JUNIPER M10 routers that communicate among them with the VRRP protocol implemented in high availability. These routers communicate with the IP transit suppliers' routers by routing protocol BGP4

IP transit suppliers (Internet Service Provider)

For the IP traffic suppliers' selection we have required a series of characteristics with the goal of providing our clients with the maximum service guarantees
In Spain, the two suppliers (Retevisión and BT Ignite) are present in the neutral point (ESPANIX) to facilitate the exchange with other carriers. In Portugal, the two suppliers are Eastécnica (Cable & Wireless) and ONI.
We also had into consideration that the physical link originated in different types of backup (fiber optic and radio link).

Each one of these two links is of 34 Mbit/s of bandwidth, finishing both in each JUNIPER (M-10) routers. Therefore, the access to InterHost center is carried out through two routers, connected between them by protocol BGP4. Thus, if an access or a router falls, the other assumes the entire load in a transparent way for the users.

Retevision possesses an agreement with Akamai, to duplicate contents in servers tolerant to failures that Akamai installs at Retevisión POPs.

Bandwidth

The bandwidth available at this time is of two accesses of 34 Mb/s each. Retevisión, regarding routers, has a bandwidth for international exits of 1 Gbit/sec. The international exits are two, Madrid and Barcelona, both to Milan by different roads. With Espanix, it connects by 2 lines SMT1 (155 Mb/s) and with Catnix through a 34 Mb/s line.

For bandwidth management (QoS) and consumption reports, software technology is utilized from CISCO Systems, packages of public domain and own developments. The SMNP management is performed with HP OpenView NNM. The remaining monitoring tools are own developments.

The IP VPN service offers our clients the benefit of having a Virtual Private Network, based on technology IP, called IP VPN (Internet Protocol Virtual Private Network), permitting to establish a "closed users group", voice communications, data, video, multimedia, etc, with security and trust. The employed technology is the tunnels' server CISCO 3005.

This service allows the clients to a direct connection with the contents office centers, so that their servers' updatings and the connections to internal services, can be done at a constant and adequate speed, regardless of the connection quality between the client and the CPDs through Internet.

This router enables connections dedicated to our clients for the kind of lines RTB RDSI (with variable or flat rate, as Novacom).

These circuits are also used as backup or security lines to other access ways.

Connections of speeds can be established between 64 Kb and 512 Kb.

The connection can be carried out to any node of InterHost's network (Madrid, Barcelona and Lisbon) regardless if in it those machines reside or not, what adds an additional security (geographical redundancy).

Currently we have a primary contracted with Retevisión.

The employed technology is CISCO 3640.

This service allows the clients with a direct connection with the contents dispatch centers, so that the updatings of their servers and of the connections to internal services can be done in a constant and adequate speed, regardless of the connection quality between the user and the CDCs through Internet. We can establish dedicated connections (point to point and Frame Relay) of speeds between 64kb and 2 Mb.

The employed technology is the tunnels server CISCO 3640.