Chapter 30: Unified Electronic Surveillance
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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to the subscriber. In this model, the subscriber’s CM may be offline when the tap session is configured or it may reboot
and move to a different downstream channel during the lifetime of the tap session. In either case, the C4/c CMTS will
identify the target CM when it registers regardless of where it appears in the C4/c CMTS, and will reestablish the tap
session automatically without external intervention.
Figure 103:
RFC 3924 Framework
For a modem that is being tapped, the C4/c CMTS will encapsulate both IPv4 and IPv6 traffic. The encapsulation header
will be an IPv4 header, but the data encapsulated can be either an IPv4 or IPv6 packet. This means the C4/c CMTS will
replicate and encapsulate all traffic with an ethertype of either 0x0800 or 0x86dd. ARP traffic (ethertype 0x0806) is not
tapped. The C4/c CMTS supplies the captured packets to an MD that handles the collection of this information for delivery
to the Law Enforcement Agency (LEA).
Tap sessions are managed using SNMPv3 control. This feature includes an implementation of the
cable intercept
CLI
command set that permits local configuration of tap sessions as well.