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It seems like they really wanted to push multicast as a "first-class" mode of the protocol, and by weaving it into the core of IPv6 they've forced everyone to

It seems like they really wanted to push multicast as a "first-class" mode of the protocol, and by weaving it into the core of IPv6 they've forced everyone to have a somewhat exercised implementation of it in their stack.

ChuckMcM 12y ago
This was my take on it as well. Multicast was a very under deployed system, one way to fix that is to make it mandatory :-)
MichaelGG 12y ago
So pushing something no one uses, and has significantly narrow uses, and still isn't deployed publicly, into the core... How is that anything but self-serving protocol designers? How do they get away with that?
- teach 12y ago
  Multicast has much more than "significantly narrow uses". When we were studying IPv6 in my network protocols course 20 years ago(!) I remember thinking how useful that would be if widely deployed.
- FeepingCreature 12y ago
  I'm a private customer, and I use IPv4 Multicast. My ISP uses it to distribute IPTV streams. Don't generalize from "I don't know anybody who uses" to "nobody uses".
  - jewel 12y ago
    A good portion of the bandwidth being used on the Internet could be done over multicast if it were widely supported. For example, popular content on Hulu could be multicast. You'd download the beginning of the video over HTTP but simultaneously tune into the multicast that started the most recently. Once the two streams meet you drop the HTTP connection. If widely deployed this would reduce costs for both Hulu and ISPs, and for places where multicast doesn't work it can fall back to HTTP.
- xorcist 12y ago
  It decreases network load (when implemented correctly). Broadcast floods used to be a real problem.
cesarb 12y ago
I believe their thinking process was more like: -> Broadcast is just a special case of multicast, where every host listens to an "all hosts" multicast group; -> Since this is a new protocol, there is no need to keep broadcast; just mandate that every host join the "all hosts" multicast group (notice that the numerically first two IPv6 multicast groups are "all hosts" and "all routers", implying they were the first ones thought of); -> Since we will always have multicast, instead of flooding ARP-like requests to everyone, let's create many "buckets" so each ARP-like request will go only to the hosts to which it's relevant, saving traffic and processing power. IPv6 is old. It's possible that when it was designed, global multicast was just around the corner. Designing the protocol to use multicast would have seemed natural back then.

ChuckMcM 12y ago

This was my take on it as well. Multicast was a very under deployed system, one way to fix that is to make it mandatory :-)

MichaelGG 12y ago

So pushing something no one uses, and has significantly narrow uses, and still isn't deployed publicly, into the core... How is that anything but self-serving protocol designers? How do they get away with that?

teach 12y ago
Multicast has much more than "significantly narrow uses". When we were studying IPv6 in my network protocols course 20 years ago(!) I remember thinking how useful that would be if widely deployed.
FeepingCreature 12y ago
I'm a private customer, and I use IPv4 Multicast. My ISP uses it to distribute IPTV streams. Don't generalize from "I don't know anybody who uses" to "nobody uses".
- jewel 12y ago
  A good portion of the bandwidth being used on the Internet could be done over multicast if it were widely supported. For example, popular content on Hulu could be multicast. You'd download the beginning of the video over HTTP but simultaneously tune into the multicast that started the most recently. Once the two streams meet you drop the HTTP connection. If widely deployed this would reduce costs for both Hulu and ISPs, and for places where multicast doesn't work it can fall back to HTTP.
xorcist 12y ago
It decreases network load (when implemented correctly). Broadcast floods used to be a real problem.

cesarb 12y ago

I believe their thinking process was more like: -> Broadcast is just a special case of multicast, where every host listens to an "all hosts" multicast group; -> Since this is a new protocol, there is no need to keep broadcast; just mandate that every host join the "all hosts" multicast group (notice that the numerically first two IPv6 multicast groups are "all hosts" and "all routers", implying they were the first ones thought of); -> Since we will always have multicast, instead of flooding ARP-like requests to everyone, let's create many "buckets" so each ARP-like request will go only to the hosts to which it's relevant, saving traffic and processing power. IPv6 is old. It's possible that when it was designed, global multicast was just around the corner. Designing the protocol to use multicast would have seemed natural back then.