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Cisco Broadband Cable Command Reference Guide
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Chapter 2 Cisco CMTS Configuration Commands
cable source-verify
The following example shows how to configure the cable interface so that the CMTS can verify IP
addresses that are on a different subnet than the one that the cable interface is using:
Router#
configure terminal
Router(config)#
ip cef
Router#(config)
interface c7/0/0
Router(config-if)#
ip verify unicast source reachable-via rx
Router(config-if)#
cable source-verify dhcp
Router(config-if)#
The following example shows the error message that is displayed if you try to configure the
leasetimer
option on a subinterface, instead of an interface:
Router#
configure terminal
Router#(config)
interface c1/0.1
Router(config-subif)#
cable source-verify dhcp
Router(config-subif)#
cable source-verify leasetimer 120
% Invalid input detected at '^' marker.
Router(config-subif)#
Related Commands
Command
Description
cable arp
Enables or disables the use of the ARP protocol for CMs and their
CPE devices.
cable helper-address
Specifies a destination IP address for User Datagram Protocol (UDP)
broadcast (DHCP) packets.
cable dhcp-giaddr
Modifies the GIADDR field of DHCPDISCOVER and
DHCPREQUEST packets with a Relay IP address before they are
forwarded to the DHCP server.
cable logging badipsource
Logs error messages about bad IP source addresses on the cable
interfaces.
cable relay-agent-option
Enables the system to insert the CM MAC address into a DHCP
packet received from a CM or host and forward the packet to a DHCP
server.
cable source-verify
leasequery-filter
downstream
Controls the number of DHCP LEASEQUERY request messages that
are sent for unknown IP addresses on all cable downstream interfaces
on the Cisco CMTS router.
cable source-verify
leasequery-filter upstream
Controls the number of DHCP LEASEQUERY request messages that
are sent for unknown IP addresses per each service ID (SID) on an
upstream.
clear cable logging
Removes all error messages about bad IP source addresses on the
cable interfaces from the error log buffer.
ip dhcp relay information
option
Enables the system to insert the CM MAC address into a DHCP
packet received from a CM or host and forward the packet to a DHCP
server.
ip dhcp smart-relay
Monitors client retransmissions when address pool depletion occurs.
ip verify unicast reverse-
path
Enables Unicast Reverse Path Forwarding (Unicast RPF), which
checks each packet received on an interface to verify that the packet’s
source IP address appears in the routing tables as belonging to that
interface, so as to prevent spoofed IP source addresses.