Summary

After completing this chapter, you should have a basic understanding of the cable modem technology. Basic Cisco CMTS and cable access router configurations were demonstrated in this chapter so that you could learn the minimum configuration requirements for both. Some of the useful IOS commands described here can help you troubleshoot and diagnose cable modem network problems.

Table 4-7 summarizes the CMTS and cable access router commands used in this chapter.

Table 4-7. Summary of Cisco IOS Software Commands Used in This Chapter
Command
Description
interface cable slot/port
Specifies the cable interface and downstream port.
cable upstream port frequency return frequency
Configures the upstream frequency.
show controller cable slot/port upstream port
Displays the upstream characteristics.
[no] cable upstream port shutdown
Activates the upstream port.
cable helper-address IP address
Specifies the IP address of a DHCP server to which UDP broadcast packets will be sent.
cable upstream port power-level dBmV
Sets the upstream input power level.
show interface cable slot/port upstream port
Displays upstream information on a cable interface.
cable upstream port channel-width [200000 | 400000 | 800000 | 1600000 | 3200000]
Specifies the upstream channel width for an upstream port.
cable spectrum-group group-number [time day hh:mm:ss] frequency upstream-frequency [dBmV]
Creates and configures a spectrum group.
cable upstream port spectrum-group group-number
Assigns a spectrum group to a single upstream.
show cable spectrum-group [group-number] [detail]
Displays information about spectrum groups on a Cisco CMTS.
cable downstream frequency 54000000-1000000000 broadcast frequency Hz
Specifies the downstream center frequency for the cable interface line card. This command is information only for uBR7246.
cable downstream annex [A | B]
Sets the MPEG framing format for a downstream port.
cable downstream interleave-depth [ 8 | 16 | 32 | 64 | 128]
Sets the downstream interleave depth.
cable downstream modulation [64qam | 256qam]
Sets the downstream format for a downstream port.
[no] cable-modem compliant bridge
Enables or disables DOCSIS-compliant bridging.
show cable flap-list
Displays the cable flap list on a Cisco CMTS.
show cable modem
Displays information for the registered and unregistered CMs.
ping docsis {IP address | MAC address}
Determines whether a specific CM can be reached from the CMTS at the DOCSIS MAC layer.
show interface cable-modem 0 counters
Displays MIB counters on the cable interface.
show controllers cable-modem 0
Displays high-level controller information for the cable access router's cable interface.
show controllers cable-modem 0 mac state
Displays detailed MAC layer information for the cable access router's cable interface.
debug cable-modem mac log
Displays detailed debugging messages for the cable interface MAC layer.

Table 4-7. Summary of Cisco IOS Software Commands Used in This Chapter
Command	Description
interface cable slot/port	Specifies the cable interface and downstream port.
cable upstream port frequency return frequency	Configures the upstream frequency.
show controller cable slot/port upstream port	Displays the upstream characteristics.
[no] cable upstream port shutdown	Activates the upstream port.
cable helper-address IP address	Specifies the IP address of a DHCP server to which UDP broadcast packets will be sent.
cable upstream port power-level dBmV	Sets the upstream input power level.
show interface cable slot/port upstream port	Displays upstream information on a cable interface.
cable upstream port channel-width [200000 \| 400000 \| 800000 \| 1600000 \| 3200000]	Specifies the upstream channel width for an upstream port.
cable spectrum-group group-number [time day hh:mm:ss] frequency upstream-frequency [dBmV]	Creates and configures a spectrum group.
cable upstream port spectrum-group group-number	Assigns a spectrum group to a single upstream.
show cable spectrum-group [group-number] [detail]	Displays information about spectrum groups on a Cisco CMTS.
cable downstream frequency 54000000-1000000000 broadcast frequency Hz	Specifies the downstream center frequency for the cable interface line card. This command is information only for uBR7246.
cable downstream annex [A \| B]	Sets the MPEG framing format for a downstream port.
cable downstream interleave-depth [ 8 \| 16 \| 32 \| 64 \| 128]	Sets the downstream interleave depth.
cable downstream modulation [64qam \| 256qam]	Sets the downstream format for a downstream port.
[no] cable-modem compliant bridge	Enables or disables DOCSIS-compliant bridging.
show cable flap-list	Displays the cable flap list on a Cisco CMTS.
show cable modem	Displays information for the registered and unregistered CMs.
ping docsis {IP address \| MAC address}	Determines whether a specific CM can be reached from the CMTS at the DOCSIS MAC layer.
show interface cable-modem 0 counters	Displays MIB counters on the cable interface.
show controllers cable-modem 0	Displays high-level controller information for the cable access router's cable interface.
show controllers cable-modem 0 mac state	Displays detailed MAC layer information for the cable access router's cable interface.
debug cable-modem mac log	Displays detailed debugging messages for the cable interface MAC layer.

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