Re: [Linux-decnet-user] MAC Address Calculations

[Patrick C. <pa...@ty...>]

On Thu, Jul 25, 2002 at 11:26:12AM +0100, Nick Holder wrote:
> Hi all,
> 
> *Newbie Alert*
> 
> I am having trouble working out the MACADDR for a given Node
> 
> >From http://linux-decnet.sourceforge.net/faq-single.html I got that
> MACADDR=AA:00:04:00:0A:04 = 1.10
> 
> And from http://linux-decnet.sourceforge.net/kernel.html I got The form of a
> DECnet physical address is AA:00:04:00:XX:XX The last two hex digits codify
> the DECnet node address. 
> 
> So MACADDR=AA:00:04:00:0A:04 
> 
> 0A = 10 - That I can get simple Hex-Dec convert
> 
> However
> 
> 04 = 1 - That I can't work out

It's because the last two hex digits are actually a 16bit number with the
address taking up 10 bits and the area the remaining six. so 1.10 is actually:

000000 00 00000000
000001 00 00001010
        4        A

> Can anyone help me get my brain arround it (and if someone wants to work out
> 5.400 I'd be most greatful *Grin*)

so. 5.400 would be

000101 01 10010000 
       15       90
       
thence:

AA:00:04:00:90:15 (cos it's in little-endian format)

There's a script in app/setether.sh that will do this for you (it's what I used
for the Debian startups).
 

patrick