The Future of Multicast – Lenny Giuliano, Distinguished Engineer @ Juniper Networks

Lenny Giuliano claims multicast is so easy and ubiquitous that even your Grandma uses it. Is that true? In this episode we talk about live streaming 4K video, AMT, multicast vs CDN and we even touch on LISP and IPv4/IPv6 transition. Multicast Menu website:

5 Replies to “The Future of Multicast – Lenny Giuliano, Distinguished Engineer @ Juniper Networks”

  1. Matthew Walster

    I’m afraid I have to vehemently disagree with the examples given. These are the three biggest issues I see:

    1. A “million simultaneous viewers” does not take down a CDN, and a 4K stream is nowhere near 40Mb/s even if that number of viewers was a huge issue. Many video CDNs approach that figure, and the biggest ones peak at several times that figure.

    2. Companies pay huge sums of money for the rights to stream sports. Most of that is recouped from advertising and subscription fees. Adverts are localised (so multiple streams are needed) and viewing the stream is not free because of those subscription fees so you need to add a DRM layer on top of the data feed, which has to be extremely tolerant of things like packet loss (especially in a wireless environment) because multicast is UDP and typically not able to retransmit like you get with a TCP stream. You can build “catch-up” services that provide missing packets on a separate stream but that is generally not realistic with live video at this scale.

    3. As well as having potentially hundreds or thousands of streams so you can have your regional advertising, you will also need alternative bitrates so that 4K can degrade to lower and lower bitrates until a reliable figure is obtained. You’re now talking about potentially tens of thousands of streams for a single program. Even with SSM you’re going to end up very limited as to the number of programs if you’re still using IPv4.

    With a deeply embedded CDN node, you get the benefits of multicast (one stream in, many streams out) with the added benefit of TCP, keeping the load off the backbone (close to the head end), and you don’t have to spend lots of time and effort ensuring that your downstream clients aren’t subscribed to feeds from the “wrong” region.

    Multicast has its uses, sure. Inter-domain multicast is used a lot in finance, yes. It is not suitable for the open internet with closed content.

    • Lenny Giuliano

      Matthew- thanks for the comments.
      1) The bitrates I mentioned are based on what I’ve found posted on the Internet. For 4k it came from Youtube ( If these numbers are not accurate, please let me know a better source for this info.
      2) Indeed, unicast streams can be used to insert ads, exchange decryption keys for access control, report user experience/audience size, etc, in conjunction with multicast delivering the actual video stream of interest.
      3) Likewise, different multicast groups can be used for different bitrates, so a receiver join different groups to switch to higher/low bitrates as needed based on the receiver’s throughput capabilities at any point in time.

  2. Koen Fredricks

    Dear. Mr. Lenny,

    Thank You for doing this podcast.
    I may want to be an engineer when I am older and what you have taught me in this podcast helped me learn about multicast and what it can do.

    Koen Fredricks

  3. Khang Le

    Hey Mr. Lenny,

    After listening to your amazing podcast, I now know that not only are you a great basketball coach, but you are a great engineer. I have learned so much from your podcast on multicasting. I may want to become an engineer one day and be just like you, so this podcast may help me one day. Although Matthew Walster disagrees with you, I on the other hand totally agree with you on all your points stated. You are clearly the alpha in the engineering world, and I want to become like you.

    Love you,
    Khang Le

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