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The Return of Multicast: Why it Succeeds in a Live Linear World

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New dynamic network infrastructures built on IP multicast will allow network “service velocity” to dramatically increase. Service velocity is the time between when the need for a service is recognized and when it’s actually delivered. Historically, service velocity was measured in years. Today we talk about it in terms of weeks.

Tomorrow we will talk about microseconds.

Before we dive into some specific indicators of this renewed multicast focus, let’s have a quick look at some key network activities across the market that exemplify this renewed focus on multicast.

In the telco ISP world, U.K. firm BT has been a pioneer in creating a proposition that combines the ISP value, the network operator value, the content service provider positioning, and, most importantly, the customer value.

BT fused these four key elements with four products:

  • BT Infinity, BT’s FTTC ISP and home gateway
  • BT Vision and YouView set-top boxes; Vision is BT’s in-house product. YouView is an interoperable architecture from a consortium BT is party to with other U.K. broadcast stakeholders.
  • BT’s own multicast enabled on-net operator CDN
  • BT Sport, the central consumer proposition on the BT Vision platform, with Premier League soccer rights as the key selling point.

With this combination, BT is now able to multicast content right through to the YouView and BT Vision devices, ensuring that BT can deliver on-net to the millions of subscribers it already reaches. You couldn’t ask for a better model. Adding a customer to the live stream has barely any infrastructure cost, and yet adds revenue. The customer pays for the CPE (the gateway and Vision/YouView box) and the cost of installation (all are amortized into the subscriber fees). And then the customer pays more for the content through upgrades to basic subscriptions. And all that revenue goes to BT. This is a perfect model for an operator, and it truly places BT in the same market as a premium cable TV operator.

In the mobile world, LTE has extensions that are enabling organizations such as U.K. 4G mobile operator EE to trail blaze with eMBMS. While it’s too involved to explore in detail here, eMBMS enables mobile operators to multicast from the mast to many devices at the same time. Early trials have been highly successful, and more operators are undertaking trials now.

Cable ISPs are not standing still either: Comcast in the U.S. and Virgin in the U.K. are also upgrading to the data over cable interface specification (DOCSIS), which will enable cable operators to IP multicast to their cable-internet subscriber basis.

What is even more interesting about the cable operators is that they are working toward defining models to allow scaled-up IP multicast within their networks, but as a transparent CDN, using a model called multicast-adaptive bitrate (M-ABR). They have a central consortium called CableLabs, which helps to define interoperability standards such as DOCSIS to help the cable industry move forward. CableLabs is central to the cable industry’s M-ABR standardization.

I caught up with Matt White, principal architect for IP video technologies at CableLabs and is leading the M-ABR. White recently moderated a session at Streaming Media West in the topic.

CableLabs has considered these scenarios in depth, and published its conclusions in the publication “Video IP Multicast: IP Multicast Adaptive Bit Rate Architecture Technical Report,” available at go2sm.com/cablelabs. Figure 2 shows how CableLabs defines the M-ABR workflow. Additional detail is available.

Multicast ABR

Multicast ABR reference interfaces, as defined by CableLabs

Critical here is the ability to drive gateway innovation so that the structure of the multicasting model across the companies that engage with it resembles the ecosystem shown. It creates alignment between the production and ingestion content service providers (CSP) and ensures a standard delivery (ABR) to the transmission network. At the same time, it allows for transparent multicast forwarding of popular content inside the operator’s last mile network, even if that content is being published and acquired in an ABR format to ensure pretty much limitless scale to the max of all nodes.

As this capability arrives, and as CSPs onboard particular services to ISP networks, premium subscriber-led service options could be offered as extra levels of service to more widely available free, ad-sponsored services. For example, we may see an HD stream free-to-air with advertising, with an ad-free 4K option at a premium to that specific ISP’s customers, as a shared income for both the ISP and the CSP.

BT has managed to vertically integrate the value chain across many levels of its business and finally drives on-net audience volumes that merit showing off the scale they can achieve. Delivery of Premier League football in the U.K. is BT’s big bragging point, with audiences in the millions. Those are big numbers for a traditional CDN to stream live. BT views these numbers as just a start. The IP nature also now scales nicely in other ways beyond concurrency; for example, it is allowing them to experiment with 4K, and they are pioneering many techniques in sports production in the 4K space as a direct result of having access to this scalable delivery model.

With the telcos, cable companies, and mobile networks all clearly exploring these models seriously now, multicast was a hot topic at the 2015 IBC event in Amsterdam, where I met with Ian Munford, director of product enablement and marketing, EMEA, media solutions, for Akamai. Akamai acquired multicast innovator Octoshape in early 2015, and Munford brought me up-to-speed on the capabilities Octoshape has brought to Akamai. Multicast is key to Akamai’s future of delivering broadcast-quality video online at scale.

Octoshape provides Akamai with the key building blocks to underpin the use of multicast in an inter-site or even inter-domain model by tunneling where required. This gives Akamai options for Tier 2 ISP delivery where multicast would traditionally have to be tunneled anyway using generic route encapsuling, automatic multicast tunneling, or other approaches. Additional emerging techniques promise to address this issue, so I hasten to add that Akamai cannot rest on its laurels despite having the Octoshape resource now in its arsenal.

Both on-net multicast and inter-net multicast are both valid and important strategies, and they will certainly widen the schism between the pureplay CDNs and the operator CDNs.

Last-mile operators who can enable native multicast at the deepest point in the network stand to benefit most from delivering content to massive live audiences. Once they have native multicast scale at the edge, they can compete on scale with cable TV service providers. They have a billing relationship with the subscriber too, which may open monetization opportunities.

That line between ISP and cable company is now blurring completely. With streaming on-net, and OTT moving to center stage in many major broadcasters’ eyes—look at Sky Go, BBC iPlayer, HBO Now, and countless others—and with online ad revenue forecast to increase by double figures in the next decade, it’s no surprise that cable operators, mobile operators, telcos, ISPs, CSPs, and consumers are all embracing IP multicast’s ability to enable audiences on the scale of broadcast TV, possibly with better-than-broadcast-TV resolution, frame rates, and other quality metrics.

Multicast has finally come of age.

This article appears in the January/February 2016 issue of Streaming Media magazine as “The Return of Multicast.”

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