how is video and live video streaming done from Netflix and other video streaming services?

[carl_townshend]

Hi All

I would like to know how all the main video providers such as Netflix, bbc etc stream there videos these days both on demand and live streams.

Would the live streams use multicast or something else ?

cheers

[Joseph W. Doherty]

Generally it's unicast, which might be over a proprietary video protocol. (Such video stream may get some "quality received" feedback, from the client's player, and use that information to adjust their transmission rate.)

[carl_townshend]

Hi Joseph

What about live video streams such as sports channels etc?

[Joseph W. Doherty]

To individual PC type clients, it's generally still multicast. However, that's often from a local "nearby" distribution server. Those servers are, in turn, fed by other upstream servers (which in traffic usage, mimics multicast - used because standard multicast isn't supported across the Internet).

To individual cable provider set top video boxes, "broadcast" (live) video can use multicast on the cable provider's network for distribution. "On-demand", within the cable provider own servers often is like the above Internet video vendor architectures.

[carl_townshend]

Hi

I am still not quite clear on the live stream to pc bit, are you saying that they would use multicast from a nearby server? so would by home broadband router just use a default route, then my ISP uses PIM to reach these servers? or would my broadband router be using PIM?

I am still a little unclear on this

cheers

[Joseph W. Doherty]

On the Internet, traffic to your client is generally never going to be multicast, although, again, upstream of the server sending traffic to you a "multicast like" architecture might be used between levels of servers.

On a proprietary cable network, using their own proprietary receiving/playing client devices, some video might actually be delivered via actual multicast, some video will be delivered via unicast.

[Vishnu Vardhan S]

Let me break down the points.

Multicast  traffic needs a protocol like PIM or IGMP which ISP's cannot use in the public network because PIM cannot scale well. 

The Netflix and other traffic are Unicast because you are only only person who is watching avenger movie example. 

Main point is :: whenever a host needs  multicast traffic it has to inform the router to send any multicast he receive via the host connected interface for this host keeps on sending a hello kind of packet once in a while, now think what if millions of pc started sending these kind of packets to the internet router. 

[Vishnu Vardhan S]

Thats an awesome question and I would be glad to answer. 

Actually the Netflix, youtube, etc comes under unicast traffic not even multicast or broadcast, the reason behind that is these are on-demand services and you can buy the service and watch whatever. For example if you are watching any ABC movie you should receive the movie contents in unicast not broadcast or multicast as only you are watching ABC movie at a given instant of time not everyone and routing multicast traffic over the internet is very tough. 

For multicast or broadcast, you can think of a radio station or a football match live streaming. 

Normally multicast needs a protocol and PIM is the protocol which most of us use. The ISP's normally filters PIM and IGMP also PIM is not designed to work in such a large scale ISP networks too. 

If you found my answers to be useful please do not hesitate to click the star button...

Thanks,

@Vishnu Vardhan S

Vishnu Vardhan CCNA CCNP JNCIA JNCIS JNCIP