OpenFlow: protocolli software defined per IP broadcast?

Ho ricevuto da NEC questo interessante comunicato stampa su un esperimento di tramissione di video IP ad alta qualità su dorsali di rete a copertura nazionale, un test effettuato utilizzando una piattaforma di controllo dei flussi delle informazioni chiamata OpenFlow. Non avevo ancora sentito parlare di questa piattaforma, proposta dalla Stanford University per la sperimentazione di nuovi protocolli di commutazione (switching) e instradamento (routine) su reti standard. Ma sto trovando il discorso estremamente affascinante nel quadro di una discussione che Radiopassioni porta avanti da tempo: quella della contrapposizione tra modelli broadcast tradizionali e la natura intrinsecamente punto-punto di Internet.

L'argomento è quello della concorrenza che i modelli "broadcast" radiotelevisivi classici, anche nella loro versione più moderna, basata su sistemi di modulazione numerica, stanno subendo dalle applicazioni di trasporto multimediale delle reti unicast IP. E l'argomento dice che quando si tratta di assicurare la delivery, la trasmissione di singoli contenuti verso una audience formata da milioni di persone, il modello borascast è ancora vincente in termini di efficienza. Per quanto capiente, una infrastruttura IP, a meno che non riesca a implementare schemi di routine "multicasting", non può assicurare - a differenza del modello multicastr - un numero di utenti potenzialmente infinito.

Ed è qui che si inseriscono le sperimentazioni basate su OpenFlow, definito da Wikipedia una istanza di Software Defined Networking. OpenFlow prende i normali dispositivi di rete IP oggi utilizzati, i router e gli switch, e li scardina come scatole di sardine, separando del tutto l'aspetto dell'informazione, del dato, da quello del controllo dei flussi delle informazioni. Questo controllo, che oggi convive con i dati dentro agli switch, viene stralciato e affidato a server pc-based. In questo modo una infrastruttura di rete esistente diventa un laboratorio per la sperimentazione di protocolli di instradamento diversi, dove sono possibili secondo la documentazione OpenFlow, anche "comportamenti" broadcast. NEC ha utilizzato tutto questo per organizzare la trasmissione video, ma si può naturalmente pensare di trasmettere qualsiasi tipo di informazione, anche audio. Quello che conta è che i confini tra modelli, con iniziative come OpenFlow, diventano sempre più labili, così come gli eventuali primati di questo o quell'altro approccio. E' un discorso difficile, ma ci mostra che non dobbiamo mai dare le cose per scontate. Gli attuali limiti di Internet sono riferiti a una Internet che tra 10 anni potrebbe essere radicalmente diversa e forse consentire un funzionamento "alla pari" con i livelli di efficienza e costo di una rete a modello broadcast convenzionale.

23 Mar 2010 11:50

NEC Uses OpenFlow Technologies to Provide Nationwide Video Transmission

Video transmission between the Sapporo Snow Festival and Pro Baseball in Okinawa

NEC Corporation (NEC), a leader in networking, communications and information technology, and the National Institute of Information and Communications Technology (NICT) (*1), announced today the successful trial of nationwide video transmission using virtualized networks and OpenFlow (*2) next generation network technologies that enable centralized control through servers. This trial marks the world’s first video transmission to multiple base locations using an OpenFlow network that spans all of Japan from Sapporo City to the islands of Okinawa (2,251 km; 1,399 miles).

The trial successfully transmitted high quality IP video through NICT’s JGN2plus research and development network, which is equipped with NEC’s OpenFlow programmable flow switch (*3) prototype. Video images were transmitted live between the Sapporo Snow Festival and the Nippon Professional Baseball camp in Okinawa over a transmission network constructed for trial purposes between five base locations (Sapporo, Tokyo, Osaka, Fukuoka, Okinawa) using programmable switches at 17 points in cooperation with a range of broadcasting offices. Moreover, the system’s reliability was further demonstrated through one-to-one transmission between single base locations, as well as simultaneous transmission between multiple base locations and multiple paths.

OpenFlow technologies enable network control by freely implementing a range of network control functions for control server middleware and centralizing network switch settings. This trial’s video transmission network was accomplished through video transmission control middleware using OpenFlow and the implementation of control servers. The successful research, development and trial of these technologies verified that high quality, highly reliable video transmission can be delivered more flexibly and at a lower cost than IP multicast technologies, which require additional functions for all routers along the path.

OpenFlow technologies for video transmission include the following features:

1) Simultaneous transmission to multiple locations (point-to-point transmission)

The control server centrally manages all transmission paths and the OpenFlow network creates optimal paths from a transmission’s origin to multiple destinations. Operational management costs for creating paths are less than conventional decentralized models because the control server enables centralized path visibility and identification. Furthermore, the control server is able to establish paths and transmit the same content to multiple recipients without allocating the group addresses that are required for transmission by conventional servers.

2) Highly reliable transmission using multiple paths (bi-casting/tri-casting transmission)

Highly reliable video transmission is realized through the development of technologies that create multiple paths from a transmission’s origin to its destination, which enables paths to be switched when an obstruction appears. Even if a path fails, uninterrupted high quality video transmission continues when services are provided with NEC’s high quality multicast technologies.

3) Virtual networks are created for each user and multiple experiments may be implemented simultaneously

One switch can be divided into several virtual switches and multiple independent virtual networks may be built. Multiple experiments and new services can be independently and simultaneously implemented by building flexible networks with the most desirable applications that are accessed through the variety of networks managed by control servers.

These trials took place in cooperation with broadcasting networks. See below for a summary.

1) Video transmission of the Sapporo Snow Festival

Successful live video transmission from Sapporo’s Hokkaido Broadcasting Co., Ltd. (HBC) to Osaka’s Mainichi Broadcasting System, Inc. (MBS) on February 4, 2010. Live video was also successfully transmitted on February 6 from Sapporo’s Odori Park to the Hokkaido Television Broadcasting Co., Ltd. (HTB) headquarters and Osaka’s Asahi Broadcasting Corporation. Implementation of OpenFlow network links between Japan and South Korea were also carried out through video transmitted from Odori Park to South Korea’s TJB (Daejeon Broadcasting) on a JGN2plus OpenFlow network and an OpenFlow network on KOREN (*5) that was independently built by Seoul's Kyungnam University.

2) Video transmission of Okinawa’s Nippon Professional Baseball camp

Successful transmission of Nippon Professional Baseball camp video from Okinawa’s Nago Multimedia Center (*6) to Osaka’s MBS from February 13 – 14, 2010.

Previously, NEC developed a programmable flow switch prototype and completed a trial between Japan and the United States (*7), in addition to jointly establishing the Clean Slate Laboratory with Stanford University (*8) and promoting a global structure of advanced research and development for realizing next generation networks. Looking forward, NEC will continue to drive technological development of next generation networks through the support of OpenFlow on network devices and contributions to innovative university and institutional research and development. These results were achieved in association with “Research and Development for Secured Cloud Networking,” contracted by the Ministry of Internal Affairs and Communications in the 2009 fiscal year.

Notes:

*1) National Institute of Information and Communications Technology (NICT). Website: http://www.nict.go.jp/index.html

*2) OpenFlow:

Programmable flow switch and control interface specifications between control servers defined by the OpenFlow consortium (http://www.openflowswitch.org/)

*3) Programmable Flow Switch:

Programmable flow switches are a new style of network equipment where, unlike conventional routers, simple packet switching mechanisms and control functions are separated. Users can freely develop and operate control middleware independently of the switching mechanism. This equipment enables the realization of advanced new technologies that link networks and cloud computing.