Chapter 17: IP Packet Filters, Subscriber Management
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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If there is a match, the C4/c CMTS increments the count for this filter and (depending on how the filter is configured):
Accepts the packet
Accepts and logs the accepted packet
Drops the packet
Drops and logs the dropped packet
Note: The logging of all allowed packets and dropped packets will cause a considerable load on the C4/c CMTS. The CMTS
automatically disables logging after reaching a limit of 1,000 packets.
Cable Modem Registration
When a cable modem registers, filter groups for upstream and downstream packets are assigned to it. Also, each modem is
assigned additional filter groups that will be used for CPEs behind that cable modem. These filter groups are based on the
device classes of the CPEs. See
Filter Groups Based on Device Class
Additionally, three sets of data are used to determine if IP packet filtering is to be applied to the modem:
First, the modem configuration file can include TLVs that instruct the C4/c CMTS to set up IP packet filtering for that
modem and the CPEs behind it.
Then, if these TLVs are not present, the C4/c CMTS checks if defaults are provisioned for the subinterface the CM or
CPE is on.
Finally, if neither of these are present, then the system-wide parameters specifying default filter groups are applied.
For the filter parameters to take effect:
The Subscriber Management feature must be enabled (default = active)
The desired filters must be configured
Cable modems must register or re-register in order to use their filters
Individual filters can be modified with new rules applied dynamically.
If a filter group has been applied to a registered modem and a new filter index is added to that group, the modem does not
have to re-register for that filter index to be enabled.
