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I have AT&T U-Verse, and they use IP multicast (and IGMPv3) for IPTV. Receivers wired into my network work just fine but receivers connected over powerline Ethernet don't. Computers connected over the same powerline link work just fine.

These powerline Ethernet adapters are sold as "bridges", but they don't actually appear to be bridging. A bridge should forward all broadcast/multicast traffic unless it can determine that such forwarding is not necessary, shouldn't it?

David Schwartz
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  • Which powerline devices are you trying to use? – K7AAY Jan 20 '15 at 05:55
  • I've tried several different ones. – David Schwartz Jan 20 '15 at 07:22
  • See [this article](http://www.tp-link.com/en/article/?faqid=484) regarding a similar problem. – harrymc Jan 20 '15 at 07:50
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    If the above didn't work, just to remark that most powerline adapters are pretty lousy with multicast. Even adapters that specify such support may not do so in a fully correct manner. – harrymc Jan 21 '15 at 10:51
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    Does multicast work on those computers mentioned? Any response from multicast nodes such as a printer or cups when you ping 224.0.0.1 from one of the powerline connected PCs? – rjt Jan 21 '15 at 23:01
  • Do you have a smart switch? Dumb switches are better when troubleshooting multicast IGMP. i have troubles equating Multicast with broadcast. A multicast client subscribes to a multicast IP address ... not exactly broadcast. 192.168.1.255 is broadcast. 224.0.0.1 is multicast. – rjt Jan 21 '15 at 23:04
  • @rjt I upgraded my switches to switches that support IGMPv3 hoping it would help. It helped with other multicast flooding issues, but not with the powerline adapters. – David Schwartz Jan 21 '15 at 23:42

1 Answers1

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Yes, they work like a bridge, but this doesn't mean they will work with IP multicast.

There are different types of network bridges. Only the simplest bridges forward all traffic to every port other than the source. Most network bridges are "learning" bridges and operate on the data link layer. They inspect packets and maintain a filtering table with addresses and ports.

Keep in mind, powerline adapters aren't just used in pairs--you can have multiple adapters networked together. Most consumer powerline adapters use the HomePlug AV or AV2 specification. These specifications include features such as QoS for video streaming and AES for security. These aren't simple devices.

Jason
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