DHCP servers so that they control how many IP addresses are assigned to the CPE devices behind each cable
modem.
MAX CPE IP
The MAX CPE IP parameter is applicable only in DOCSIS 1.1 cable networks and is an optional parameter.
This parameter specifies whether the cable modem should perform IP address filtering on the CPE devices.
If so, this attribute also specifies the maximum number of simultaneous IP addresses that are permitted behind
the modem at any one time.
The MAX CPE IP parameter is configured in the DOCSIS configuration file (TLV 35), or by using SNMP
commands to set the docsDevCpeIpMax attribute (in DOCS-CABLE-DEVICE-MIB) for the cable modem.
By default, this parameter is not enabled and the Cisco CMTS does not actively manage CPE devices, unless
you enable the use of the MAX CPE IP parameter by using the
cable submgmt default active
command.
The
cable submgmt default max-cpe
command can be used to limit the number of IP addresses behind the
cable modem.
If this feature is enabled, the cable modem learns the allowable IP addresses the first time that the CPE device
sends an IP packet out into the network. The IP addresses are added to the docsDevFilterCpeTable table. This
address table is cleared automatically when the cable modem is reset or powered off, or you can manually
clear the IP address table by setting the docsSubMgtCpeControlReset attribute in the appropriate table entry
for this cable modem.
The CMTS uses the MAX CPE IP value as part of its own filtering process, but the two filters operate
independently on the cable modem and CMTS.
Tip
MAX CPE IPv6
The MAX CPE IPv6 parameter is an optional parameter and specifies the maximum number of simultaneous
IPv6 addresses that are permitted for a cable modem at any time.
The MAX CPE IPv6 parameter is configured in the DOCSIS 3.0 configuration file (TLV 63), or by using the
SNMP commands to set the docsSubmgt3BaseCpeMaxIpv6PrefixDef attribute (in DOCS-SUBMGT3-MIB)
for the cable modem. By default, this parameter is not enabled and the Cisco CMTS does not actively manage
CPE devices, unless the use of the MAX CPE IPv6 parameter is enabled by using the
cable submgmt default
active
command. The
cable submgmt default max-ipv6-cpe
command can be used to limit the number of
IPv6 addresses allowed behind a cable modem.
When the MAX CPE IPv6 feature is enabled, the cable modem learns the allowable IPv6 addresses the first
time that the CPE device sends an IPv6 packet out into the network. The IPv6 addresses are added to the IPv6
address table. The address table is cleared automatically when the cable modem is reset or powered off.
Interoperation of the Maximum CPE Parameters
The different methods of CPE control can all be active simultaneously. They can interact with one another
but do not conflict with one another. The table lists each method and compares their characteristics.
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Maximum CPE and Host Parameters
MAX CPE IP