From: John Galt Kupec (jkupec2@xxxxxxxxxx)
Date: Sun Nov 28 1999 - 15:44:33 GMT-3
Brian Van Benschoten wrote:
>
> I'm having trouble figuring out exactly how to map the IP multicast address
> to the multicast MAC address. I know that the lower 23 bits of the IP
> address map to the MAC address. I think I'm doing something wrong.
>
> 224.0.1.35 01 00 5e 00 01 23 ( I think this is correct)
> 224.0.1.22 01 00 5e 00 11 66 ( I don't see how you get this one)
Yeah, seems like the second one should end in 01 16 to me.
>
> anyone have a few tips or shortcuts on how to do the conversion. How about
> a few examples that you know are correct. Then I can try to figure them
> out.
It's pretty straightforward I think. Possibly seeing some wrong
answers have made it seem more difficult than it is?
>
> how would you convert these ?
>
> 224.0.5.5
> 224.1.1.1
> 229.1.1.1
01 00 5e 00 05 05
01 00 5e 01 01 01
01 00 5e 01 01 01
Last two are the same because of the 32:1 address ambiguity when an
Layer 3 IP multicast address is mapped to a Layer 2 IEEE MAC address.
How about this one:
225.65.10.154
John
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