Cisco Broadband Cable Command Reference Guide

Cisco CMTS Feature Summary
Table 2-2 Principle Software Features (continued)
2-4
Cisco Broadband Cable Command Reference Guide
Chapter 2 Cisco Cable Modem Termination System Commands
Feature Category Item
Packet Filtering Options Ability to filter packets based on the combination of IP address, upper-layer protocol
(for example, UDP, TCP, ICMP) and upper-layer protocol’s port number or Internet
Control Message Protocol (ICMP) type in the IP packet.
Ability to configure source IP address filtering on RF subnets to prevent subscribers
from using source IP addresses that are not valid for the IP subnet that is physically
connected to their CM and CPE device.
Per modem filters (per CM or host access lists)—Ability to filter incoming packets from
individual hosts or CMs based on the source MAC or IP address; allows lists to be
specified on a per-interface and per-direction basis.
Cable monitor—Ability to filter a selection of MAC messages, map messages, and data
packets to access lists, MAC address and upstream port numbers; enables time-stamping
of each packet and permits the option of stripping away the DOCSIS header for data
packets; this increases the CMTS administrator’s ability to manage network variables,
understand network issues that can affect application performance and functionality, and
helps to resolve interoperability problems.
Provisioning and Maintenance
Options
DHCP client ID or remote ID options to limit the number of customer premises
equipment (CPE) devices per CM.
“Command max-CPE configuration file entry override”—Allows the CMTS
administrator to override a CM’s DOCSIS configuration file setting that specifies the
maximum number of CPE devices the CM supports.
DHCP CM host ID (CM and host subnet addressing) to modify the giaddr field of
DHCPDISCOVER packets based on whether the source is a CM or a host to help verify
addresses.
Upstream address verification—Verifies CM and PC addresses to ensure that Service
Identifier (SID) and MAC addresses are consistent; this helps ensure that addresses are
not spoofed; CMTS administrator can determine the IP and MAC address of a given CM
and the SID number that shows the IP and MAC addresses of all devices learned in the
CM’s MAC table. Using customer databases, the administrator can cross-reference the
spoofing CM and PC and prevent use.
Enhanced source address verification—Verifies that each upstream data packet from a
CM comes from the source IP address in the packet known to be associated with the CM.
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