Re: Mapping IP multicast address to MAC address

From: Brian Van Benschoten (vader@xxxxxxxxxxxx)
Date: Sun Nov 28 1999 - 17:50:28 GMT-3


   
>
> > 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

would this be???

01 00 5e 41 0a 9a

let me see if I have this correct. you take the 3rd and 4th "octet" of the
ip address and just do a hex conversion using the windows calculator. You
take the 2nd octet and convert it to binary and see if it takes more than 7
bits, if it does you need to make sure it starts with a 0 and then convert
it back to HEX.

Am I on the right track here?

lets change the above to:

225.200.10.154, this would be ?
01 00 5e 48 0a 9a

since 200 is 11001000 you need to change it to 0100100 and convert that to
HEX.



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