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Cisco SB101 & Cablemodem DHCP Problem

davegaff asked
Last Modified: 2013-12-14
I recently obtained a Cisco SB101 router and have attempted to connect to my cablemodem service.  For some reason, the router will not obtain an IP address via DHCP.  If I connect my cablemodem directly to my laptop I am able to obtain an IP address successfully.  I've confirmed that my ISP does not do any MAC filtering.  Further, if I then write down the IP address obtained on the laptop and then set my router to the same static IP address my internet works just fine.  Can anyone help?
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How are you configuring the router's WAN interface?

Should just be 'ip address DHCP'


'ip address dhcp' is what I've done (I've also tried this through Cisco SDM)

Sure sounds like your ISP has locked in on the one MAC.  You could test this theory by getting the mac address of the computer that worked, then issuing the command 'mac-address xxxx.yyyy.zzzz'

You could also try the Cable modem reset trick.  Unplug the cable modem from power(don't just turn it off) for 15 minutes, then hook it back up with the router connected.
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