Cisco bids to control IPTV
Grabs for underlying architecture
This Cisco product might just as well have been invented directly for AT&T, and its well publicized issues with error correction as the way to go in IPTV, as prescribed by Microsoft’s IPTV system. Microsoft itself has gone on record pointing out that using advanced error correction does not exclude the use of packet re-transmission, in parallel and so may welcome this move.
But the genius in this announcement is that after all the fuss that Microsoft went to, to alter the format of IPTV, by introducing fast channel change from network servers, achieved by blending unicast data gradually with the multicast, has been copied by Cisco, but in the router.
So once a channel change is issued by a set top the system must calculate what I-frames it needs to render the next frame, and get them to the set top at breakneck speed, and instead of going back to the head end, they are supplied by the nearest Cisco 7600 router. This happens in parallel with subscribing to a new multicast channel. The two streams of data must be “blended” at the set top, so that it doesn’t attempt to render a frame before it is ready, but once again by putting this job into the fastest elements of the network, Cisco can ensure that this happens before the buffer from the last program has departed the set top, and before it fills the buffer for the channel change.
We think the channel change will come down to around 350 to 500 milliseconds before it is totally complete, which is roughly in line with the Microsoft IPTV system.
Cisco also announced other features relating to troubleshooting and proactive operator alerts to go with this VQE system.
The other half of the Cisco announcements relate to what sounds like a simple server architecture which allows modular upgrades to VoD servers and adds the load balancing and resilience that Cisco is used to adding for internet web servers.
Cisco calls the new VoD device its Content Delivery System (CDS) which it says will support VoD, network PVR, time-shift TV, but will also support multiple device types, so that VoD can be served just as well to PCs and handsets, as much as to set tops, managing the screen resizing and protocol differences. The system can also splice each video stream with its own advertising and Cisco says that it will be ready for a future when operators choose to offer targeted advertising or personalized content.
The Cisco CDS consists of networked Cisco Content Delivery Engines (CDEs) which can ingest, store, distribute, personalize, and stream content. These are grouped into arrays for storage and/or streaming, working together as a single logical system. Capacity can be expanded by simply attaching additional CDEs to the array.
In August Cisco bought privately held Arroyo Video Solutions, an on-demand TV server business, for about $92m in cash and it is likely that the Arroyo product line forms the basis of this announcement, but even if it is, there is a heavy hand of Cisco know-how in this announcement.
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