 |
|
Services | Backbone operation | Technologies | R&D | Networks | Qualification | Events |
 | RNP2 breaks interstate speed recordInternational traffic capacity doubled In March, RNP updated six of the links of RNP2, its national academic network. The connection between Rio de Janeiro and São Paulo increased from 45 Mbps to 622 Mbps. This is the greatest known capacity of an interstate link in Brazil. The other states to directly benefit from this upgrading were the Federal District, Rio Grande do Sul, Santa Catarina, Paraná and Minas Gerais, each of them receiving a 155 Mbps connection. The auction made to lease lines, the public bid on the telecommunications market and the change to a new technology represented an economy of 80% in relation to the costs of the previous connections. The same model will be used to update the other links of the network all over the country. Meanwhile, the new technology adopted, the SDH (synchronous digital hierarchy), will co-exist with the ATM (asynchronous transfer mode) and the Frame Relay, used in the 20 network connections that still have not been updated. The greatest advantage of the SDH is in the overhead reduction. All data package transmitted has a heading that serves to identify it and order it correctly at the end of the receiver. The overhead is the ratio between the size of the heading and the size of the data field. "In ATM, the IP packages are embedded in cells that have a 5-byte long heading. Thus, if totally full, a 155 Mbps channel takes around 131.75 Mb of information (IP packages) and ‘wastes’ about 23.25 Mb, only to transmit the heading of the ATM cells," explains Ari Frazão, manager of RNP’s Engineering and Operation Center. However, ATM does not work alone. The cells need a transport protocol to take the data along the optical fiber. What was done in RNP’s new lines was to eliminate this ATM layer; consequently, the data are now directly packed in the protocol – in this case, the SDH. This way, the overhead diminished. While the ATM cells produce an estimated 15% overhead, the SDH protocol brings in its heading a 4.4% overhead. It means that the same 155 Mbps channel that carried only 131.75 Mb of information now carries 148.2 Mb of information with the SDH – a gain of more than 10%. All of RNP2’s new connections will use either SDH or PDH (plesiochronous digital hierarchy) and will have from 4 to 155 Mbps. Peering doubles the international traffic capacity The international traffic capacity has also been increased. On January 29th, a 155 Mbps link was activated for traffic exchange (peering) between RNP2 network and the network of the telecommunications company Global Crossing. Through this channel, RNP can make part of its traffic with foreign countries flow since Global Crossing has an idle capacity in its connection with the United States. In practice, it is as if the international traffic capacity had doubled, benefiting the institutions using the Brazilian academic network, which already counted on an international link of 155 Mbps on RNP2 – not to mention the 45 Mbps connection with the network of the North American Internet2 project. Soon, RNP will increase its international traffic capacity even more, through the Clara network, which will interconnect Latin American and European academic networks. Updated connections
See the map of RNP2 network at http://www.rnp.br/en/backbone/ [RNP, 03.19.2004] |