[nSLUG] Re: MAC-address/router question

Rich budman85 at eastlink.ca
Fri Dec 9 03:15:57 AST 2005

On Fri, 2005-12-09 at 01:29 -0400, Mike Spencer wrote:
> me> My router's web-based admin interface says its MAC address is
> me> xx:xx:xx:xx:xx:1F.
> rmckay> Does it say which MAC address?
> No.  And it only mentions one.

The cable modem should have its own MAC.
The router should have a WAN and LAN MAC address.
If its wireless add another MAC for WLAN.

I think the cable company watches what MAC the modem binds to and also
assigns that.  I saw this happen while changing nics on my old linux box

I recently updated my firewall to a wireless router. I didnt want to
wait a day or two for them to get around to binding the new address. So
I used the MAC address from my old firewall, this way the MAC was
already bound.  I was up and running in a few minutes.

The only OS I seen MAC addresses hardcoded was in Windows. Not sure if
XP will let you do it, I gave up on Windows after 98se, been using Linux
ever since.

SunOS/Solaris and Linux can assign any MAC to any network device.
Trying to remember what the reason was, I think it was a way to
multi-home nics.  Cisco has trunking, Solaris can also trunk nics, but
its called something else.  Have to think back, its been a bit, haven't
been admining in 5 years.  See was developing does. :)

Was this a new router?  if not , maybe it was an prior config.

> rmckay> The ethernet and radio interfaces certainly will have
> rmckay> different MAC addresses (although they are likely to be close
> rmckay> to each other if they were both allocated by the same
> rmckay> manufacturer).

> So:
>     + The radio interface of the router that my wireless card accesses and
>     + The cable ethernet interface of the same router that my cabled
>       boxes access
> will "certainly have different MAC addresses"?  Do I have that right?


> Huh.  I didn't know that.  Never even thought of it.  I guess it makes
> sense.  I was thinking of the router ethernet interface as a single
> device that could do ethernet over either cable or radio.  From what
> you say, that's the wrong concept.  Guess I need to read some RFCs on
> how wireless works.
> Thanks,
> - Mike
Rich <budman85 at eastlink.ca>


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