Last October GridNetworks announced that it had raised $9.5M in Series A funding for its GridCasting content delivery network (CDN). For whatever reason, though, Cisco decided to wait until today to reveal that it was a strategic investor in that round.

GridNetworks wants to provide the underlying technology that streams high quality television content over the internet and into homes. Its architecture is part traditional CDN, part peer-to-peer network. In simple terms, the content delivered by GridCasting is initially buffered by a handful of data centers. Then after about 10-30 seconds of video playback, the data centers hand over delivery responsibilities to about 16 peers (other consumers of online video content who have cached it already and can serve as mini data centers themselves).

This method isn’t entirely unique - Vuze uses the Azureus BitTorrent protocol to do something very similar. And it’s not entirely clear whether the P2P method of distributing high definition content really provides much of an advantage over centralized streaming methods. Other non-P2P streaming companies like BitGravity would certainly argue that the cost savings and performance increases from P2P are not substantial (and the legal situation vis-a-vis net neutrality is still up in the air anyhow).

However, it’s notable that Cisco has taken an interest in this hybrid CDN technology. Their investment and ongoing relationship should give GridNetworks the opportunity to integrate its so-called “connector” software into non-computer devices like Linksys entertainment centers. The connector software is necessary for the streaming and P2P to work, whether with a computer or other device (currently only Windows is supported, with Mac support coming soon).