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ARP: resolve IP multicast #18

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sergachev
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According to RFC1112, addresses 224.0.0.0 – 239.255.255.255 (starting 0b1110) should be resolved by placing the low-order 23-bits of the IP address into the low-23 bits of the Ethernet multicast address 01-00-5E-00-00-00. Another explanation here.
This allows, for instance, sending multicast PTP packets to 224.0.1.129, which maps to 01:00:5e:00:01:81.

@gncemre23
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According to RFC1112, addresses 224.0.0.0 – 239.255.255.255 (starting 0b1110) should be resolved by placing the low-order 23-bits of the IP address into the low-23 bits of the Ethernet multicast address 01-00-5E-00-00-00. Another explanation here. This allows, for instance, sending multicast PTP packets to 224.0.1.129, which maps to 01:00:5e:00:01:81.

Do we need to implement IGMP protocol to receive the multicast IP packets?

@sergachev
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Do we need to implement IGMP protocol to receive the multicast IP packets?

If your switch / router does IGMP snooping - yes, your device needs to send an IGMP join message to start receiving multicast.

@gncemre23
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Do we need to implement IGMP protocol to receive the multicast IP packets?

If your switch / router does IGMP snooping - yes, your device needs to send an IGMP join message to start receiving multicast.

Thank you, that saves my life :)

@alexforencich alexforencich force-pushed the master branch 2 times, most recently from 3155340 to 80a2573 Compare May 16, 2022 00:59
@alexforencich alexforencich force-pushed the master branch 2 times, most recently from ae942ad to 870cebb Compare February 11, 2024 21:00
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@sergachev @gncemre23 @alexforencich