[aprssig] Help with DSL Modem

Gregg Wonderly gregg at wonderly.org
Tue Oct 10 20:49:24 CDT 2006

Joel Maslak wrote:
> On Oct 10, 2006, at 4:39 PM, Brady Small wrote:
>> Did you clone the old MAC address out of the old router and use the  
>> MAC clone feature in the new router?
> DSL doesn't use MAC addresses.

The layer above that is the issue.  At the pseudo ethernet layer that is in 
place to allow ARP to be used, the modem does have a MAC address.  Since these 
devices are sold in the store, and people can connect them themselves, the 
telephone companies and the cable companies, and others with infrastructure that 
is commissioned into service enmasse, need something to control who gets 
service.  So, on the service provider's end, many use the "MAC" address of the 
modem to control DHCP activities and thus address assignment.  Now, those who 
are devious, and in the know about address ranges might be able to find a 
working address, but, in general, you have to have a known MAC address to get 

Gregg Wonderly

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