Usage Guidelines
This command
enables field technicians to add a temporary CPE device behind the subscriber’s
cable modem. The temporary CPE device shares the same SID settings as the
original CPE device, even though the temporary CPE device has a different MAC
address. The original CPE device automatically changes from
dhcp
cpe to
static
cpe in the CMTS host routing tables, and the CPE
device continues to receive service with the same SID.
To disable
Cisco CMTS Static CPE Override on the Cisco CMTS, use the
no form of
this command. This automatically updates the routing tables and enables the MAC
address from the technician’s laptop for a future field service connection at a
different location.Prior to using this command, the first (existing) DHCP CPE
device maintains its DHCP dynamic MAC address behind the cable modem. The SID
is assigned to this IP address.
However, by
enabling Static CPE override, you gain the following states and options on two
CPE devices behind the cable modem.
- The SID definition on
the first CPE device is assigned a different static IP address. This enables
you to change the existing (dynamic) DHCP IP address to a static IP address
without first clearing the DHCP CPE host entries from the Cisco CMTS. The CPE
IP state changes from
dhcp to
static
cpe.
- This static override
allows a second CPE device with a second MAC address behind the same cable
modem with SID1 to be assigned same IP address as the first CPE device.
Note |
The second
CPE device changes from
dhcp
cpe to
static
cpe in the CMTS host tables.
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The DOCSIS 1.1
Subscriber Management MIB (DOCS-SUBMGT-MIB) creates and maintains a number of
tables that describe the state of subscriber management for the CMs and CPE
devices being serviced by the Cisco CMTS. The CMTS creates rows in these tables
for each CM and CPE device when the CM registers with the CMTS, and if the CM
does not specify a value for an attribute in this table, the CMTS uses the
defaults specified by the
cable
submgmt
default command.
Timesaver |
The
DOCS-SUBMGT-MIB MIB contains its own default values for these attributes, and
those defaults can be overridden by giving the appropriate SNMP SET commands.
The
cable
submgmt
default command, however, allows the new defaults
to be included in the Cisco IOS configuration file so that the defaults are
automatically reconfigured whenever the CMTS reboots or reloads.
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Note |
The
cable
submgmt
default command sets only the default value for
these attributes. These default values are used only if the CM does not specify
other values when it registers with the CMTS. If the CM does specify different
values at registration time, those values are used instead of these default
values.
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The attributes
in DOCS-SUBMGT-MIB control how the CMTS manages the CPE devices behind a CM and
the filters that are applied to the traffic to and from a particular CM and its
CPE devices. The following sections describe the relationship between the
different forms of the
cable
submgmt
default commands and the attributes in
DOCS-SUBMGT-MIB.
CPE Management
The first form
of the
cable
submgmt
default command controls the default values for
the entries in the docsSubMgtCpeControlTable, which controls how the CMTS
manages the CPE devices for each CM:
cable
submgmt
default
active
Sets the
docsSubMgtCpeActiveDefault attribute, which is the default value for the
docsSubMgtCpeControlActive attribute in docsSubMgtCpeControlTable. This
attribute controls whether the CMTS performs CPE management for a particular
CM.
- The
cable
submgmt
default
active
command sets the default to TRUE, which specifies that the
CMTS is to manage CPE devices by enforcing the MAX-CPE number and the
implemented filters.
- The
no
cable
submgmt
default
active
command sets the default to FALSE (the default value), which
specifies that the CMTS is not to perform CPE management for the particular CM.
cable
submgmt
default
learnable
Sets the
docsSubMgtCpeLearnableDefault attribute, which is the default value for the
docsSubMgtCpeControlLearnable attribute in docsSubMgtCpeControlTable. This
attribute controls whether the CMTS learns the IP addresses for CPE devices
behind a particular CM.
- The
cable
submgmt
default
learnable
command sets the default to TRUE (the default value), which
specifies that the CMTS is to learn the IP addresses for the CPE devices behind
the CM, up to the value specified by the MAX-CPE parameter. The CMTS learns the
IP addresses by monitoring the traffic sent by the CPE devices, and the first
CPE devices to transmit traffic are the first CPE devices to be learned.
- The
no
cable
submgmt
default
learnable
command sets the default to FALSE, which specifies that the
CMTS does not learn the IP addresses for the CPE devices behind a particular
CM. Instead, the IP addresses for each CM that is to be allowed access must be
specified in the DOCSIS configuration file.
cable
submgmt
default
max-cpe
cpe-num
Sets the
docsSubMgtCpeMaxIpDefault attribute, which specifies the default value for the
docsSubMgtCpeControlMaxCpeIp attribute in docsSubMgtCpeControlTable. This
attribute specifies the maximum number of IP addresses that can transmit
traffic through a particular CM. The possible range is 0 to 1024, and the
original default is 16.
Note |
The MAX-CPE
attribute is used only when the CMTS is actively managing CPE devices for the
CM.
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Filter Group
Management
The second form
of the
cable
submgmt
default command controls the default values for
the entries in the docsSubMgtCmFilterTable, which assigns the CM to one or more
filter groups. A filter group specifies what filters are applied to the traffic
going to or coming from each particular CM or CPE device. Filter groups can be
numbered 0 to 1024, where 0 specifies that no filtering is done for that
particular traffic type.
Note |
The actual
filters specified in these commands must be created by setting the appropriate
attributes in the DOCS-SUBMGT-MIB MIB using SNMP SET commands.
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cable
submgmt
default
filter-group
cpe
downstream
group-id
Sets the
ocsSubMgtSubFilterDownDefault attribute, which is the default value for the
docsSubMgtSubFilterDownstream attribute in the docsSubMgtCmFilterTable. This
attribute applies to downstream traffic that is sent to the CPE devices behind
a particular CM.
cable
submgmt
default
filter-group
cpe
upstream
group-id
Sets the
docsSubMgtSubFilterUpDefault attribute, which is the default value for the
docsSubMgtSubFilterUpstream attribute in the docsSubMgtCmFilterTable. This
attribute applies to upstream traffic that is sent by the CPE devices behind a
particular CM.
cable
submgmt
default
filter-group
cm
downstream
group-id
Sets the
docsSubMgtCmFilterDownDefault attribute, which is the default value for the
docsSubMgtCmFilterDownstream attribute in the docsSubMgtCmFilterTable. This
attribute applies to downstream traffic that is addressed to a particular CM.
cable
submgmt
default
filter-group
cm
upstream
group-id
Sets the
docsSubMgtCmFilterUpDefault attribute, which is the default value for the
docsSubMgtCmFilterUpstream attribute in the docsSubMgtCmFilterTable. This
attribute applies to upstream traffic that is sent by a particular CM.
Note |
For more
information about using static CPE override, see the Cisco CMTS Static CPE
Override feature on Cisco.com.
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Examples
The following
commands specify that the CMTS defaults to actively managing the CPE devices
for each CM that registers, allowing and learning up to four IP addresses for
the CPE devices behind that CM. The
cable
submgmt
default
max-cpe
command specifies the number of IPv6 addresses
permitted behind a CM which includes all IPv6 addresses of all the CPE's.
Router# configure terminal
Router(config)# cable submgmt default active
Router(config)# cable submgmt default learnable
Router(config)# cable submgmt default max-cpe 4
The following
commands specify that the CMTS defaults to actively managing the CPE devices
for each CM that registers. Each CM, however, must specify its own MAX-CPE
value; otherwise, that value defaults to 0 and all traffic to and from the CPE
devices for that CM is blocked.
Router# configure terminal
Router(config)# cable submgmt default active
Router(config)# cable submgmt default max-cpe 0
The following
commands specify that the CMTS defaults to not actively managing the CPE
devices for each CM that registers. However, if the CM at registration time
indicates that the CMTS is to actively manage the CPE devices, the CMTS
defaults to allowing only one CPE device. Learning also is disabled, so that
one CPE device, therefore, must be specified in the DOCSIS configuration file
that the CM uses to register.
Router# configure terminal
Router(config)# no cable submgmt default active
Router(config)# no cable submgmt default learnable
Router(config)# cable submgmt default max-cpe 1
The following
commands specify that the CMTS defaults to assigning three filter groups to
each CM that registers. Unless the CM indicates otherwise at registration time,
downstream and upstream traffic for the CPE devices behind the CM is filtered
according to the rules for filter groups 20 and 21, respectively. Filter group
1 is applied to the downstream traffic addressed to the CM. Upstream traffic
sent by the CM, however, is not filtered.
Router# configure terminal
Router(config)# cable submgmt default filter-group cpe downstream 20
Router(config)# cable submgmt default filter-group cpe upstream 21
Router(config)# cable submgmt default filter-group cm downstream 1
Router(config)# cable submgmt default filter-group cm upstream 0
Note |
The above
example assumes that filter groups 1, 20, and 21 have already been created on
the CMTS using the appropriate SNMP commands.
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