Okay..... now I see you have the same answer I came up with. So I guess I
can assume the boot IS wrong. Thanks again......Paul
"Ole Drews Jensen" <[EMAIL PROTECTED]> wrote in message
2019FB428FD3D311893700508B71EBFB54AEB7@RWR_MAIL_SVR">news:2019FB428FD3D311893700508B71EBFB54AEB7@RWR_MAIL_SVR...
> You can probably find a lot of good sites about Multicast if you start
> searching for them on the web.
>
> I thought the Multicast IP to MAC address in the BCMSN book by Karen Webb
> was a little confusing, but after I read the LAN switching book by Clark
and
> Hamilton, I understood exactly what to do.
>
> If you picture an IP address as octet1.octet2.octet3.octet4, the way to
> convert it to a MAC address is:
>
> 1) Take (octet2, octet3 and octet4)
> 2) AND octet2 with 127 (or subtract 128 if octet2 >= 128)
> 3) Convert each octet to hexadecimal values
> 4) MAC = 01.00.5E.new-octet2.new-octet3.new-octet4
>
> Let's take your example 224.0.165.45
>
> 1) 0.165.45
> 2) 0.165.45
> 3) 00.A5.2D
> 4) MAC = 01.00.5E.00.A5.2D
>
> As you can see on this method, 224 uses the 3 first bits in octet1 to
> specify it self as a Multicast IP address, which leaves 5 bit left for
> addresses. These 5 bits plus the 1 bit of octet2 that is cleared gives you
6
> bits or 32 different IP addresses that will end up with the same MAC
> address.
>
> Let's take IP address 225.128.165.45 and do the same 4 steps:
>
> 1) 128.165.45
> 2) 0.165.45
> 3) 00.A5.2D
> 4) MAC = 01.00.5E.00.A5.2D
>
> This means that you have to think about this before you assign your
> Multicast IP addresses to networks where you have more than one group,
> because you could end up with two different groups pointing to the same
> physical address.
>
> Hth,
>
> Ole
>
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ole Drews Jensen
> Systems Network Manager
> CCNA, MCSE, MCP+I
> RWR Enterprises, Inc.
> [EMAIL PROTECTED]
> http://www.CiscoKing.com
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NEED A JOB ???
> http://www.oledrews.com/job
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> -----Original Message-----
> From: jim klane [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, February 06, 2001 2:04 PM
> To: [EMAIL PROTECTED]
> Subject: RE: Possible BCMSN Errata??
>
>
>
> do you have a link on thie multicast stuff?
>
>
>
> let me know
>
>
>
> jim
>
>
>
> >From: Ole Drews Jensen
> >Reply-To: Ole Drews Jensen
> >To: "'Paul Mandella'" , [EMAIL PROTECTED]
> >Subject: RE: Possible BCMSN Errata??
> >Date: Tue, 6 Feb 2001 13:20:31 -0600
> >
> >I do not have the book in front of me, but yes, the given binary IP
address
>
> >is 224.0.165.45 and the MultiCast MAC will be 01-00-5E-00-09-2D.
> >
> >Ole
> >
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Ole Drews Jensen
> > Systems Network Manager
> > CCNA, MCSE, MCP+I
> > RWR Enterprises, Inc.
> > [EMAIL PROTECTED]
> > http://www.CiscoKing.com
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > NEED A JOB ???
> > http://www.oledrews.com/job
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >
> >
> >-----Original Message-----
> >From: Paul Mandella [mailto:[EMAIL PROTECTED]]
> >Sent: Tuesday, February 06, 2001 12:48 PM
> >To: [EMAIL PROTECTED]
> >Subject: Possible BCMSN Errata??
> >
> >
> >Hello All. While working on examples of converting Multicast IP addresses
> to
> >Multicast MAC addresses in the Cisco book I came across one that doesn't
> >seem to be correct. I ask for opinions on the following to possibly save
my
>
> >sanity on this one. Thanks
> >
> >The IP address in the book is 224.0.9.45
> >It is shown as 1110 0000 0000 0000 1010 0101 0010 1101
> >
> >Seems to me that this IP should read 224.0.165.45 and this would work out
> to
> >the Multicast MAC being 01-00-5e-00-a5-2d and not the 01-00-5e-00-09-2d
> >given in the book.
> >
> >Did I just lose my mind on this one?? I have not found errata on Cisco
> Press
> >site that corrects this. Thanks for any input
> >
> >Paul
> >
> >
> >_________________________________
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