Hello.

When you use:

clear cable modem {mac/ip} reset = CMTS send instruction to CM that restart ()

clear cable modem {mac/ip} delete = delete cablemodem data (TXpwr, RXpwr, PHY, Counters, etc) then to no exist in the database of CMTS this mac, doesn´t send DOCSIS headers (similar to hello message) to Cable Modem and not receiving them the modem will restart.

http://www.cisco.com/c/en/us/td/docs/cable/cmts/cmd_ref/b_cmts_cable_cmd_ref/b_cmts_cable_cmd_ref_chapter_01010.html

Regards.