Cisco Systems UBR900 Using Multiple PCs with the Cable Access Router, Step Command Purpose

		Using Multiple PCs with the Cable Access Router
Step	Command	Purpose
3	uBR924(config-if)#cable-modem downstream saved channel	Modify the saved downstream channel setting and
	ds-frequency us-power	upstream power value. If you do this, you must specify an
		exact downstream frequency and a power value.1
4	uBR924(config-if)#cable-modem fast-search	Enable a faster downstream search algorithm.

1Use the no cable-modem downstream saved channel ds-frequencyus-powercommand to remove a saved frequency and power setting from NVRAM.

Using Multiple PCs with the Cable Access Router

The MAX CPE parameter in the DOCSIS configuration file determines how many PCs or other CPE devices are supported by a particular cable access router. The default value for the MAX CPE parameter is 1, which means only one PC can be connected to the cable access router unless this value is changed.

The DOCSIS 1.0 specification states that a CMTS cannot age-out MAC addresses for CPE devices. Thus, if MAX CPE = 1, the first PC that is connected to a cable access router is normally the only one that the CMTS recognizes as valid. If you wish to replace an existing PC or change its network interface card (NIC) to one that has a different MAC address, the CMTS will refuse to let the PC come online because this would exceed the maximum number of CPE devices specified by the MAX CPE parameter.

If you wish to replace an existing PC or NIC, use one of the following workarounds:

•Use the clear cable host mac address reset command on the Cisco uBR7200 series router to remove the PC’s MAC address from the router’s internal address tables. The PC’s MAC address will be rediscovered and associated with the correct cable access router during the next DHCP lease cycle.

•Power off the cable access router for approximately one minute and then power it back on so that the PC’s MAC address will be rediscovered and associated with the cable access router during the normal provisioning process. The PC might also have to be rebooted.

•Increase the value of the MAX CPE parameter in the cable access router’s DOCSIS configuration file so that it can accommodate the desired number of PCs. Reset the cable access router to force it to load the updated configuration file.

Configuring the Cisco uBR900 Series Cable Access Routers 45