Troubleshooting Tips for the
Cisco uBR924 Cable Access Router
Feature Summary
This document describes the Cisco IOS troubleshooting commands that may be used by cable
service providers to verify communication between a Cisco uBR924 cable access router and other
peripheral devices installed in the HFC headend such as a Cisco uBR7200 series universal
broadband router, a DHCP server, and a TFTP server.
Benefits
The Cisco uBR924 cable access router troubleshooting system provides the following benef its:
• A MAC-layer system log file that provides a snapshot of detailed reasons why an interface might
reset, along with all the negotiations that occurred between the Cisco uBR924 cable access router
and the CMTS. Over 220 possible description fields exist in this log, which is displayed using the
show controllers cable-modem 0 mac log command from privileged EXEC mode.
• Debug does not need to be turned on in order to troubleshoot a Cisco uBR924 cable access router.
• The progression of normal data-over-cable communication events is clearly explained,
simplifying the resolution of faulty system connections.
Restrictions
• Troubleshooting and diagnostic tasks can be performed on the Cisco uBR924 from a remote
location using TELNET.
When using the Cisco uBR924 cable access router, k eep the following restrictions and limitations in
mind:
• The Cisco uBR924 is able to implement multiple classes of service (CoS) on the cable interface;
howeve r , separate CoS streams are only a v ailable when the cable access router is connected to a
headend that supports multiple CoS per cable access router. In addition, the configuration file
downloaded to the cable access router must specify the use of multiple classes of service.
• If the Cisco uBR924 cable access router is connected to a DOCSIS 1.0 headend that does not
support multiple CoS per cable access router, v oice and data will be mixed, and v oice traf f ic will
be transmitted on a best effort basis. This may cause poorer voice quality and lower data
throughput when calls are being made from the cable access router’s telephone ports. Voice
quality may also be affected when transmitting or downlo ading large f iles, or at other times when
network traffic is heavy.
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 1
Related Features and Technologies
Note The Cisco uBR924 cable access router is typically configured at the headend. Most cable
service operators do not permit local configuration at subscriber sites.
Caution Before attempting to reconfigure a Cisco uBR924 cable access router at a subscriber site, contact
your network management, provisioning manager, or billing system administrator to ensure remote
configuration is allowed. If remote configuration is disabled, settings you make and save at the local site will
not remain in effect after the cable access router is re set or powered off and back on. Instead, settings will
return to the previous configuration.
Related Features and Technologies
The Cisco uBR924 cable access router is intended to be used in conjunction with a Cisco uBR7200
series universal broadband router or other DOCSIS-based CMTS located at the cable operator’s
headend facility.
Related Documents
For related information on the Cisco uBR924 cable access router , refer to the following documents:
Platforms
• Cisco uBR924 Cable Access Router Quick Start Guide
• Cisco uBR924 Cable Access Router Installation and Configuration Guide
• Regulatory Compliance and Safety Info. for the Cisco uBR924 Cable Access Router
• Cisco uBR7246 Installation and Configuration Guide
• Cisco uBR7223 Installation and Configuration Guide
• Cisco uBR7200 Series Configuration Notes
• Cisco Network Registrar for the uBR7200 Series
• Regulatory and Safety Compliance for the Cisco uBR7246
• Regulatory and Safety Compliance for the Cisco uBR7223
• Cisco uBR7200 Series Features
• Cisco uBR7200 Series Feature Enhancements
• Cisco uBR7200 Series Feature Enhancements in Release 12.0
• Cisco uBR7200 Series Installation and Configuration Guide
The Cisco uBR924 cable access router is a single-platform standalone device; it works in
conjunction with the Cisco uBR7200 series universal broadband routers.
Cisco IOS Release 12.0(5)T
2
Prerequisites
In order to use the Cisco uBR924 cable access router for data-over -cable applications, the following
conditions must be met:
• The Cisco uBR7200 series universal broadband router or other DOCSIS-based CMTS must be
installed at the cable headend and configured. Refer to the Cisco uBR7246 Installation and
Configuration Guide or the Cisco uBR7223 Installation and Configuration Guide for detailed
information.
• The Cisco uBR924 cable access router must be physically installed and cabled as follows:
— To the headend via CATV coaxial cable
— To at least one PC via the straight-through yello w Et hernet cable supplied with the cable
• The PC(s) connected to the Cisco uBR924 cable access router must be configured for Internet
Protocol (IP).
• The cable service provider must have a correctly configured network DHCP server and
Electronic Industries Association (EIA) downstream channel.
• Cisco IOS Release 11.3(4)NA or later must be running on the Cisco uBR924 cable access router.
When the cable access router is up and running, you can display the IOS release number by
entering the show version command from user EXEC mode.
Related Documents
access router. Refer to the Cisco uBR924 Cable Access Router Quick Start Guide for detailed
information.
Note If the Cisco uBR7246 universal broadband router at the cable headend is using MC16 modem
cards, Cisco IOS Release 11.3(7)NA or later must be running on the Cisco uBR924 cable access
router.
In order to use the Cisco uBR924 cable access router for VoIP-over -cable applications, the following
additional conditions must be met:
• Cisco IOS Release 12.0(4)XI1 or higher must be running on the Cisco uBR924 cable access
router.
• In order to run VoIP Fax, the uBR924 cable access router must be configured for voice and you
must be using Cisco IOS Release 12.0(5)T or higher.
• For multiple CoS (class of service) support, the CMTS must allow the definition of multiple
service identifiers (SIDs) on the upstream. If the CMTS is a Cisco uBR7200 series universal
broadband router, Cisco IOS Release 12.0(4)XI1 or higher must be used on the headend router.
• The Cisco uBR924 must be configured to operate in routing mode.
Supported MIBs and RFCs
The Cisco uBR924 cable access router supports the following MIBs and RFCs:
• Cisco Standard MIBs:
— Cisco Product MIB
— Cisco Chassis MIB
— Cisco Syslog MIB
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 3
List of Terms
— Cisco Flash MIB
— Bridge MIB
— IF MIB
— MIB-II
• Cisco VoIP MIBs:
— Cisco Voice IF MIB
— Cisco Voice Dial-Control MIB
— Cisco Voice Analog IF MIB
— Cisco Dial-Control MIB
• Radio Frequency Interface Specification—Developed by the Multimedia Cable Network System
(MCNS) consortium. It defines the radio-frequency interface specification for high-speed
data-over-cable systems.
• CiscoWorks—Network management program for planning, troubleshooting, and monitoring
Cisco internetworks. CiscoWorks uses Simple Network Management Protocol (SNMP) to
monitor all SNMP devices.
— For more information about CiscoWorks on CCO, follow this path:
Products & Ordering: Cisco Products: Network Management: CiscoWorks
• Radio Frequency Interface (RFI) MIB—Specific to Data-Over-Cable Service Interface
• Cable Device MIB—Records statistics related to the configuration and status of the
For descriptions of supported MIBs and how to use MIBs, see Cisco’s MIB web site on CCO at
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
List of Terms
broadband—Transmission system that combin es multiple independent signals onto one cable. In
the cable industry, broadband refers to the frequency-division multiplexing of many signals in a wide
bandwidth of RF frequencies using a hybrid fiber-coaxial (HFC) network.
CATV—Originally stood for Community Antenna Television. Now refers to any coaxial or fiber
cable-based system that provides television services.
— For more information about CiscoWorks on the Documentation CD-ROM, follow this path:
Cisco Product Documentation: Network Management: CiscoWorks
Specification (DOCSIS) cable implementations. The RIF MIB provides an interface that permits
management of the Cisco uBR924 cable access router over the cable or Ethernet interface. Using
SNMP management applications, this MIB allows access to statistics such as MAC, driver
configuration, and counters.
Cisco uBR924 cable access router. Statistics include an events log and device status. The Cable
Device MIB is very similar to the RFI MIB in that both allow access to statistics; they are
different in that the Cable Device MIB reports statistics on the cable access router , while the RFI
MIB reports statistics on the radio frequency transmissions over the cable television line.
cable modem (CM)—A modulator-demodulator device that is placed at subscriber locations to
conve y data communications on a cable tele vision system. The Cisco uBR924 cable access router is
also a cable modem.
Cisco IOS Release 12.0(5)T
4
List of Terms
Cable Modem Termination System (CMTS)—A termination system locat e d at the cab le
television system headend or distribution hub which provides complementary functionality to the
cable modems, enabling data connectivity to a wide-are network.
cable router—A modular chassis-based router optimized for data-over-CATV hybrid fiber-coaxial
(HFC) applications.
carrier—A signal on which another, lower-frequency sign al is mod ulated in order to transport the
lower-frequency signal to another location.
Carrier-to-Noise—C/N (also CNR). The difference in amplitude between the desired RF carrier
and the noise in a portion of the spectrum.
channel—A specific frequency allocation and bandwidth. Do wnstream channels used for tele vision
are 6 MHz wide in the United States; 8 MHz wide in Europe.
CM—cable modem.
CMTS—Cable Modem Termination System.
coaxial cable—The principal physical media over which CATV systems are built.
dB—Decibel. A measure of the relative strength of two signals.
dBm—Decibels with respect to one milliwatt. A unit of RF signal strength used in satellite work and
other communications applications.
dBmV—Decibels with respect to one millivolt in a 75-ohm system. The unit of RF power used in
CATV work in North America.
DHCP—Dynamic Host Configuration Protocol. This protocol provides a mechanism for allocating
IP addresses dynamically so that addresses can be reused when hosts no longer need them.
DOCSIS—Data Over Cable Service Interface Specification. Defines technical specifications for
equipment at both subscriber locations and cable operators’ headends.
downstream—The set of frequencies used to send data from a headend to a subscriber.
FDM—Frequency Division Multiplexing. A data transmission method in which a number of
transmitters share a transmission medium, each occupying a different frequency.
FEC—Forward Error Correction. In data transmission, a process by which additional data is added
that is derived from the payload by an assigned algorithm. It allows the receiver to determine if
certain classes of errors have occurred in transmission and, in some cases, allows other classes of
errors to be corrected.
headend—Central distribution point for a CATV system. Video signals are recei ved here from
satellite (either co-located or remote), frequency converted to the appropriate channels, combined
with locally originated signals, and rebroadcast onto the HFC plant. For a CATV data system, the
headend is the typical place to create a link between the HFC system and any external data networks.
HFC—Hybrid fiber-coaxial (cable network). Older CATV systems were provisioned using only
coaxial cable. Modern systems use fiber transport from the headend to an optical node located in the
neighborhood to reduce system noise. Coaxial cable runs from the node to the subscriber. The fiber
plant is generally a star configuration with all optical node fibers terminating at a headend. The
coaxial cable part of the system is generally a trunk-and-branch configuration.
host—Any end-user computer system that connects to a network. In this document, the term host
refers to the computer system connected to the LAN interface of the cable access router.
ingress noise—Over-the-air signals that are inadv ertently coupled into the nominally closed coaxial
cable distribution system. Ingress noise is difficult to track down and intermittent in nature.
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 5
List of Terms
MAC layer—Media Access Control sublayer. Controls access by the cable access router to the
CMTS and to the upstream data slots.
MCNS—Multimedia Cable Network System Partners Ltd. A consortium of cable companies
providing service to the majority of homes in the United States and Canada. This consortium has
decided to drive a standard with the goal of having interoperable cable access routers.
MSO—Multiple System Operator. A cable service provider that operates in more than one
geographic area, thus having multiple headend facilities.
narrowband—A single RF frequency.
NTSC—National Television Systems Committ ee. A United States TV technical standard, named
after the organization that created the standard in 1941. Specifies a 6 MHz- wide modulated signal.
PAL—Phase Alternating Line. The TV system used in most of Europe, in which th e color carrier
phase definition changes in alternate scan lines. Utilizes an 8 MHz-wide modulated signal.
QAM—Quadrature Amplitude Modulation. A method of modulating digital signals onto a
radio-frequency carrier signal in which the value of a symbol consisting of multiple bits is
represented by amplitude and phase states of the carrier. QAM is a modulation scheme mostly used
in the downstream direction (64-QAM, 256-QAM). 16-QAM is expected to be usable in the
upstream direction. Numbers indicate number of code points per symbol. The QAM rate or the
number of points in the QAM constellation can be computed by 2 raised to the power of <number
of bits/symbol>. For example, 16-QAM has 4 bits per symbol, 64-QAM has 6 bits per symbol, and
256-QAM has 8 bits per symbol.
QPSK—Quadrature Phase-Shift Keying. A digital modulation method in which there are 2 data bits
represented with each baud symbol.
ranging—The process of acquiring the correct timing offset such that the transmissions of a cable
access router are aligned with the correct mini-slot boundary.
RF—Radio frequency. The portion of the electromagnetic frequency spectrum from 5 MHz to
approximately 860 MHz.
SECAM—TV system used in France and elsewhere, utilizing an 8 MHz-wide modulated signal.
SID (Service ID)—A number that defines (at the MAC sublayer) a particular mapping between a
cable access router (CM) and the CMTS. The SID is used for the purpose of upstream bandwidth
allocation and class-of-service management.
Signal-to-Noise—S/N (also SNR). The difference in amplitude between a baseband signal and the
noise in a portion of the spectrum.
spectrum reuse—CATV’s most fundamental concept. Historically, the over-the-air spectrum has
been assigned to many purposes other than that of carrying TV signals. This has resulted in an
inadequate supply of spectrum to serve the needs of vie wers. Cable can reuse spectrum that is sealed
in its aluminum tubes.
subscriber unit (SU)—An alternate term for cable access router. See cable access router.
upstream—The set of frequencies used to send data from a subscriber to the headend.
Cisco IOS Release 12.0(5)T
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CMTS to Cable Modem Network Topology
Figure 1 shows the physical relationship between the devices in the HFC network and the
Cisco uBR924 cable access router.
Figure 1 Sample Topology
List of Terms
Proxy server
Analog TV
Digital TV
100BT
Cisco
uBR7246
CMTS
ISP
WAN
ATM, FDDI, 100BT...
100BT
100BT
100BT
Upconvertor
DS-RF 54-860 Mhz
Fiber
Transceiver
IP-related
ISP @ home...
MSD: Maintenance Service
Organization, Cable companies
Fiber node
(Telephone pole,
underground box)
80 km
1000 ft
Distribution
amplifier
Top
amplifier
Drop box
Cisco u BR904
cable modem
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 7
13304
Step 1—Understand How Basic Initialization Works
Troubleshooting Steps
To troubleshoot a malfunctioning cable modem, perform the following tasks:
• Step 1—Understan d How Basic Initialization Works
• Step 2—Connect to the Cisco uBR924
• Step 3—Display the Cisco uBR924’s MAC Log File
• Step 4—Interpret the MAC Log File and Take Action
• (Optional) Step 5— Use Addit ional Troubleshooting Commands
Step 1—Understand How Basic Initialization Works
Before you troubleshoot a Cisco uBR924 cable access router, you should be familiar with the cable
modem initialization process. See Figure 2 and Table 1. Understanding this flowchart and sequence
of events will help you determine where and why connections fail.
The sequence numbers shown in Figure 2 are explained in Table 1, which appears after the
illustration. The Cisco uBR924 will complete all the steps in this flowchart each time it needs to
reestablish ranging and registration with the CMTS.
Cisco IOS Release 12.0(5)T
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Step 1—Understand How Basic Initialization Works
0
1
Figure 2 Cable Modem Initialization Flowchart
Power
on
Scan for
1
2
3
4
downstream
channel
Downstream
sync
established
Obtain
upstream
parameters
Upstream
parameter
acquired
Start
Ranging
Ranging and
auto adjust
completed
Establish
IP
connectivety
Establish
security
Security
established
Transfer
operational
parameters
Transfer
complete
Register with
the Cisco
uBR7246
Registration
complete
Baseline
privacy
initialization
6
7
8
9
complete
Establish
5
time of
Time of day
established
IP
day
Baseline
privacy
initialized
Operational
1
2960
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 9
Step 2—Connect to the Cisco uBR924
.
Table 1 Cable Modem Initialization Sequences and Events
Sequence Event Description
1 Scan for a downstream channel and
establish synchronization with the
CMTS.
2 Obtain upsteam channel parameters. The Cisco uBR924 waits for an upstream channel descriptor
3 Start ranging for power adjustments. The ranging process adjusts the Cisco uBR924’s transmit
4 Establish IP connectivity. The Cisco uBR924 sends a DHCP request to obtain an IP
5 Establish the time of day. The Cisco uBR924 accesses the TOD server for the current
6 Establish security. Keys for privacy are exchanged between the Cisco uBR924
7 Transfer operational parameters. After the DHCP and security operations are successful, the
8 Perform registration. The Cisco uBR924 registers with the CMTS. After it is
9 Comply with baseline privacy. If the software image running on the Cisco uBR924 includes
10 Enter the operational maintenance
state.
The Cisco uBR924 acquires a downstream channel from the
CMTS and saves the last operational frequenc y in non-v olatile
memory . The Cisco uBR924 tries to reacquire the saved
downstream channel the next time a request is made.
Note An ideal downstream signal is one that synchronizes
QAM symbol timing, FEC framing, MPEG packetization, and
recognizes downstream sync MAC layer messages.
(UCD) message from the CMTS. The UCD provides
transmission parameters for the upstream channel.
power . Ranging is performed in two stages: ranging state 1 and
ranging state 2.
address, which is needed for IP connectivity. The DHCP
response also includes the name of a file that contains
additional configuration parameters, the TFTP server’s
address, and the Time of Day (TOD) server’s address.
date and time, which is used to create time stamps for logged
events (such as those displayed in the MAC log file).
and the CMTS.
Note The Cisco uBR924 cable access router supports baseline
privacy in Cisco IOS Release 12.0(5)T and later.
Cisco uBR924 downloads operational parameters from a
configuration file stored on the cable company’s TFTP server.
initialized, authenticated, and configured, the Cisco uBR924 is
authorized to forward traffic onto the cable network. .
baseline privacy, link level encryption keys are exchanged
between the CMTS and the Cisco uBR924.
As soon as the Cisco uBR924 has successfully completed the
above sequence, it enters operational maintenance state.
Step 2—Connect to the Cisco uBR924
Telnet to the IP address assigned to the cable interface or Ethernet interface. If the interface is not
up, you will need to access the Cisco IOS software via the RJ-45 console port, which is a physical
port on the back of the Cisco uBR924.
Note For security purposes, the console port on the Cisco uBR924 may have been deactivated by
the cable service company prior to installation at the subscriber site.
Cisco IOS Release 12.0(5)T
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Step 3—Display the Cisco uBR924’s MAC Log File
Step 3—Display the Cisco uBR924’s MAC Log File
A MAC-layer circular log file is stored inside the Cisco uBR924. This file contains a history of the
log messages such as state event activities and timestamps. This is the most valuable information for
troubleshooting the cable interface.
The MAC log file is displayed by entering the show controllers cable-modem 0 mac log command
from privileged EXEC mode.
The most useful display fields in this log file are the reported state changes. These fields are preceded
by the message
through the various processes involved in estab lishi ng communication and registration with the
CMTS. The
the normal state when the interface is shut down.
Note Because the MAC log file only holds a snapshot of 1023 entries at a time, you should try to
display the Cisco uBR924’s log file within 5 minutes after the reset or problem occurs.
The following is the normal progression of states as displayed by the MAC log:
wait_for_link_up_state
ds_channel_scanning_state
wait_ucd_state
wait_map_state
ranging_1_state
ranging_2_state
dhcp_state
establish_tod_state
security_association_state
configuration_file_state
registration_state
establish_privacy_state
maintenance_state
CMAC_LOG_STATE_CHANGE. These fields show how the Cisco uBR924 progresses
maintenance_state is the normal operational state; the wait_for_link_up_state is
Note To translate this output into more meani ngful information, see “Step 4—Interpret the MAC
Log File and Take Action” on page 13.
Following is an example of what the MAC log file looks like when the Cisco uBR924 interface
successfully comes up and registers with the CMTS. The output you see is directly related to the
messages that are exchanged between the Cisco uBR924 and the headend CMTS.
uBR924# show controllers cable-modem 0 mac log
508144.340 CMAC_LOG_DRIVER_INIT_IDB_RESET 0x08098FEA
508144.342 CMAC_LOG_LINK_DOWN
508144.344 CMAC_LOG_LINK_UP
508144.348 CMAC_LOG_STATE_CHANGE ds_channel_scanning_state
508144.350 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 88/453000000/855000000/6000000
508144.354 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 89/93000000/105000000/6000000
508144.356 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 90/111250000/117250000/6000000
508144.360 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 91/231012500/327012500/6000000
508144.362 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 92/333015000/333015000/6000000
508144.366 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 93/339012500/399012500/6000000
508144.370 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 94/405000000/447000000/6000000
508144.372 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 95/123015000/129015000/6000000
508144.376 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 96/135012500/135012500/6000000
508144.380 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 97/141000000/171000000/6000000
508144.382 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 98/219000000/225000000/6000000
508144.386 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 99/177000000/213000000/6000000
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 11
Step 3—Display the Cisco uBR924’s MAC Log File
508144.390 CMAC_LOG_WILL_SEARCH_SAVED_DS_FREQUENCY 699000000
508145.540 CMAC_LOG_UCD_MSG_RCVD 3
508146.120 CMAC_LOG_DS_64QAM_LOCK_ACQUIRED 699000000
508146.122 CMAC_LOG_DS_CHANNEL_SCAN_COMPLETED
508146.124 CMAC_LOG_STATE_CHANGE wait_ucd_state
508147.554 CMAC_LOG_UCD_MSG_RCVD 3
508147.558 CMAC_LOG_UCD_NEW_US_FREQUENCY 20000000
508147.558 CMAC_LOG_SLOT_SIZE_CHANGED 8
508147.622 CMAC_LOG_FOUND_US_CHANNEL 1
508147.624 CMAC_LOG_STATE_CHANGE wait_map_state
508148.058 CMAC_LOG_MAP_MSG_RCVD
508148.060 CMAC_LOG_INITIAL_RANGING_MINISLOTS 40
508148.062 CMAC_LOG_STATE_CHANGE ranging_1_state
508148.064 CMAC_LOG_RANGING_OFFSET_SET_TO 9610
508148.066 CMAC_LOG_POWER_LEVEL_IS 28.0 dBmV (commanded)
508148.068 CMAC_LOG_STARTING_RANGING
508148.070 CMAC_LOG_RANGING_BACKOFF_SET 0
508148.072 CMAC_LOG_RNG_REQ_QUEUED 0
508148.562 CMAC_LOG_RNG_REQ_TRANSMITTED
508148.566 CMAC_LOG_RNG_RSP_MSG_RCVD
508148.568 CMAC_LOG_RNG_RSP_SID_ASSIGNED 2
508148.570 CMAC_LOG_ADJUST_RANGING_OFFSET 2408
508148.572 CMAC_LOG_RANGING_OFFSET_SET_TO 12018
508148.574 CMAC_LOG_ADJUST_TX_POWER 20
508148.576 CMAC_LOG_POWER_LEVEL_IS 33.0 dBmV (commanded)
508148.578 CMAC_LOG_STATE_CHANGE ranging_2_state
508148.580 CMAC_LOG_RNG_REQ_QUEUED 2
508155.820 CMAC_LOG_RNG_REQ_TRANSMITTED
508155.824 CMAC_LOG_RNG_RSP_MSG_RCVD
508155.826 CMAC_LOG_ADJUST_RANGING_OFFSET -64
508155.826 CMAC_LOG_RANGING_OFFSET_SET_TO 11954
508155.828 CMAC_LOG_RANGING_CONTINUE
508165.892 CMAC_LOG_RNG_REQ_TRANSMITTED
508165.894 CMAC_LOG_RNG_RSP_MSG_RCVD
508165.896 CMAC_LOG_ADJUST_TX_POWER -9
508165.898 CMAC_LOG_POWER_LEVEL_IS 31.0 dBmV (commanded)
508165.900 CMAC_LOG_RANGING_CONTINUE
508175.962 CMAC_LOG_RNG_REQ_TRANSMITTED
508175.964 CMAC_LOG_RNG_RSP_MSG_RCVD
508175.966 CMAC_LOG_RANGING_SUCCESS
508175.968 CMAC_LOG_STATE_CHANGE dhcp_state
508176.982 CMAC_LOG_DHCP_ASSIGNED_IP_ADDRESS 188.188.1.62
508176.984 CMAC_LOG_DHCP_TFTP_SERVER_ADDRESS 4.0.0.1
508176.986 CMAC_LOG_DHCP_TOD_SERVER_ADDRESS 4.0.0.32
508176.988 CMAC_LOG_DHCP_SET_GATEWAY_ADDRESS
508176.988 CMAC_LOG_DHCP_TZ_OFFSET 360
508176.990 CMAC_LOG_DHCP_CONFIG_FILE_NAME platinum.cm
508176.992 CMAC_LOG_DHCP_ERROR_ACQUIRING_SEC_SVR_ADDR
508176.996 CMAC_LOG_DHCP_COMPLETE
508177.120 CMAC_LOG_STATE_CHANGE establish_tod_state
508177.126 CMAC_LOG_TOD_REQUEST_SENT
508177.154 CMAC_LOG_TOD_REPLY_RECEIVED 3107617539
508177.158 CMAC_LOG_TOD_COMPLETE
508177.160 CMAC_LOG_STATE_CHANGE security_association_state
508177.162 CMAC_LOG_SECURITY_BYPASSED
508177.164 CMAC_LOG_STATE_CHANGE configuration_file_state
508177.166 CMAC_LOG_LOADING_CONFIG_FILE platinum.cm
508178.280 CMAC_LOG_CONFIG_FILE_PROCESS_COMPLETE
508178.300 CMAC_LOG_STATE_CHANGE registration_state
508178.302 CMAC_LOG_REG_REQ_MSG_QUEUED
508178.306 CMAC_LOG_REG_REQ_TRANSMITTED
508178.310 CMAC_LOG_REG_RSP_MSG_RCVD
508178.312 CMAC_LOG_COS_ASSIGNED_SID 5/19
508178.314 CMAC_LOG_COS_ASSIGNED_SID 6/20
508178.316 CMAC_LOG_COS_ASSIGNED_SID 7/21
Cisco IOS Release 12.0(5)T
12
Step 4—Interpret the MAC Log File and Take Action
508178.318 CMAC_LOG_RNG_REQ_QUEUED 19
508178.320 CMAC_LOG_REGISTRATION_OK
508178.322 CMAC_LOG_REG_RSP_ACK_MSG_QUEUED 0
508178.324 CMAC_LOG_STATE_CHANGE establish_privacy_state
508178.326 CMAC_LOG_NO_PRIVACY
508178.328 CMAC_LOG_STATE_CHANGE maintenance_state
You can display other aspects of the MAC layer by using variations of the show controllers
cable-modem 0 mac command:
uBR924# show controllers cable-modem 0 mac ?
errors Mac Error Log data
hardware All CM Mac Hardware registers
log Mac log data
resets Resets of the MAC
state Current MAC state
For examples and descriptions of how to use these keywords, see the show controllers
cable-modem mac command reference page.
Step 4—Interpret the MAC Log File and Take Action
The MAC log file giv es a detailed history of initialization events that occurred in the Cisco uBR924.
All pertinent troubleshooting information is stored here.
The following sample log file is broken down into the chronological sequence of events listed belo w .
Sample comments are also included in the log file.
• Event 1—Wait for the Link to Come Up
• Event 2—Scan for a Downstream Channel, then Synchronize
• Event 3—Obtain Upstream Parameters
• Event 4—Start Ranging for Power Adjustments
• Event 5—Establish IP Connectivity
• Event 6—Establish the Time of Day
• Event 7—Establish Security
• Event 8—Transfer Operational Parameters
• Event 9—Perform Registration
• Event 10—Comply with Baseline Privacy
• Event 11—Enter the Maintenance State
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 13
Step 4—Interpret the MAC Log File and Take Action
Event 1—Wait for the Link to Come Up
When the Cisco uBR924 cable access router is powered on and begins initialization, the first event
that occurs is that the MAC layer informs the cable access router drivers that it needs to reset. The
LINK_DOWN and LINK_UP fields are similar to the shut and no shut conditions on a standard Cisco
interface.
uBR924# show controllers cable-modem 0 mac log
528302.040 CMAC_LOG_LINK_DOWN
528302.042 CMAC_LOG_RESET_FROM_DRIVER
528302.044 CMAC_LOG_STATE_CHANGE wait_for_link_up_state
528302.046 CMAC_LOG_DRIVER_INIT_IDB_SHUTDOWN 0x08098D02
528302.048 CMAC_LOG_LINK_DOWN
528308.428 CMAC_LOG_DRIVER_INIT_IDB_RESET 0x08098E5E
528308.432 CMAC_LOG_LINK_DOWN
528308.434 CMAC_LOG_LINK_UP
Event 2—Scan for a Downstream Channel, then Synchronize
Different geographical regions and different cable plants use different frequency bands. The
Cisco uBR924 cable access router uses a built-in default frequency scanning feature to address this
issue. After the Cisco uBR924 finds a successful downstream frequenc y channel, it saves the channel
to NVRAM. The Cisco uBR924 recalls this value the next time it needs to synchronize its frequency .
The
CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND field tells you what frequency the Cisco
uBR924 will scan for. The
frequency the Cisco uBR924 locked onto and saved to NVRAM for future recall. The
CMAC_LOG_DS_64QAM_LOCK_ACQUIRED field communicates the same information. The
CMAC_LOG_DS_CHANNEL_SCAN_COMPLETED field indicates that the scanning and synchronization was
successful.
508144.348 CMAC_LOG_STATE_CHANGE ds_channel_scanning_state
508144.350 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 88/453000000/855000000/6000000
508144.354 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 89/93000000/105000000/6000000
508144.356 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 90/111250000/117250000/6000000
508144.360 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 91/231012500/327012500/6000000
508144.362 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 92/333015000/333015000/6000000
508144.366 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 93/339012500/399012500/6000000
508144.370 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 94/405000000/447000000/6000000
508144.372 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 95/123015000/129015000/6000000
508144.376 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 96/135012500/135012500/6000000
508144.380 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 97/141000000/171000000/6000000
508144.382 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 98/219000000/225000000/6000000
508144.386 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 99/177000000/213000000/6000000
508144.390 CMAC_LOG_WILL_SEARCH_SAVED_DS_FREQUENCY 699000000
508145.540 CMAC_LOG_UCD_MSG_RCVD 3
508146.120 CMAC_LOG_DS_64QAM_LOCK_ACQUIRED 699000000
508146.122 CMAC_LOG_DS_CHANNEL_SCAN_COMPLETED
CMAC_LOG_WILL_SEARCH_SAVED_DS_FREQUENCY field tells you the
A frequency band is a group of adjacent channels. These bands are numbered from 88 to 99. Each
band has starting and ending digital carrier frequencies and a 6 MHz step size. For example, a search
of EIA channels 95-97 is specified using band 89. The starting frequency is 93 MHz, the ending
frequency is 105 MHz.
The Cisco uBR924’s default frequency bands correspond to the North American EIA CATV channel
plan for 6 MHz channel slots between 90 MHz and 858 MHz. For example, EIA channel 95 occupies
the slot 90-96 MHz. The digital carrier frequency is specified as the center frequency of 93 MHz.
Channel 95 is usually specified using the analog video carrier frequency of 91.25 MHz, which lies
1.75 MHz below the center of the slot.
Cisco IOS Release 12.0(5)T
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Step 4—Interpret the MAC Log File and Take Action
The search table is arranged so that the first frequencies tried are above 450 MHz. Because many
CATV systems have been upgraded from 450 MHz to 750 MHz coaxial cable, digital channels have
a high chance of being assigned in the new spectrum. The search table omits channels below 90 MHz
and above 860 MHz since the DOCSIS specification does not mandate their coverage.
Some CATV systems use alternative frequency plans such as the IRC (Incrementally Related
Carrier) plan and HRC (Harmonically Related Carrier) plan. Cisco cable access routers support both
of these plans. Most of the IRC channel slots overlap the EIA plan.
Event 3—Obtain Upstream Parameters
The Cisco uBR924 waits for an upstream channel descriptor (UCD) message from the headend
CMTS. The UCD provides transmission parameters for the upstream channel.
508146.124 CMAC_LOG_STATE_CHANGE wait_ucd_state
508147.554 CMAC_LOG_UCD_MSG_RCVD 3
508147.558 CMAC_LOG_UCD_NEW_US_FREQUENCY 20000000
508147.558 CMAC_LOG_SLOT_SIZE_CHANGED 8
508147.622 CMAC_LOG_FOUND_US_CHANNEL 1
508147.624 CMAC_LOG_STATE_CHANGE wait_map_state
508148.058 CMAC_LOG_MAP_MSG_RCVD
508148.060 CMAC_LOG_INITIAL_RANGING_MINISLOTS 40
Event 4—Start Ranging for Power Adjustments
The ranging process adjusts the transmit power of the cable access router. The Cisco uBR924
performs ranging in two stages: ranging state 1 and ranging state 2.
The
CMAC_LOG_POWER_LEVEL_IS field is the power level that the CMTS told the Cisco uBR924 to
adjust to. The
CMAC_LOG_RANGING_SUCCESS field indicates that the ranging adjustment was
successful.
508148.062 CMAC_LOG_STATE_CHANGE ranging_1_state
508148.064 CMAC_LOG_RANGING_OFFSET_SET_TO 9610
508148.066 CMAC_LOG_POWER_LEVEL_IS 28.0 dBmV (commanded)
508148.068 CMAC_LOG_STARTING_RANGING
508148.070 CMAC_LOG_RANGING_BACKOFF_SET 0
508148.072 CMAC_LOG_RNG_REQ_QUEUED 0
508148.562 CMAC_LOG_RNG_REQ_TRANSMITTED
508148.566 CMAC_LOG_RNG_RSP_MSG_RCVD
508148.568 CMAC_LOG_RNG_RSP_SID_ASSIGNED 2
508148.570 CMAC_LOG_ADJUST_RANGING_OFFSET 2408
508148.572 CMAC_LOG_RANGING_OFFSET_SET_TO 12018
508148.574 CMAC_LOG_ADJUST_TX_POWER 20
508148.576 CMAC_LOG_POWER_LEVEL_IS 33.0 dBmV (commanded)
508148.578 CMAC_LOG_STATE_CHANGE ranging_2_state
508148.580 CMAC_LOG_RNG_REQ_QUEUED 2
508155.820 CMAC_LOG_RNG_REQ_TRANSMITTED
508155.824 CMAC_LOG_RNG_RSP_MSG_RCVD
508155.826 CMAC_LOG_ADJUST_RANGING_OFFSET -64
508155.826 CMAC_LOG_RANGING_OFFSET_SET_TO 11954
508155.828 CMAC_LOG_RANGING_CONTINUE
508165.892 CMAC_LOG_RNG_REQ_TRANSMITTED
508165.894 CMAC_LOG_RNG_RSP_MSG_RCVD
508165.896 CMAC_LOG_ADJUST_TX_POWER -9
508165.898 CMAC_LOG_POWER_LEVEL_IS 31.0 dBmV (commanded)
508165.900 CMAC_LOG_RANGING_CONTINUE
508175.962 CMAC_LOG_RNG_REQ_TRANSMITTED
508175.964 CMAC_LOG_RNG_RSP_MSG_RCVD
508175.966 CMAC_LOG_RANGING_SUCCESS
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 15
Step 4—Interpret the MAC Log File and Take Action
Event 5—Establish IP Connectivity
After ranging is complete, the cable interface on the cable access router is UP. Now the
Cisco uBR924 accesses a remote DHCP server to get an IP address. The DHCP request also includes
the name of a file that contains additional configuration parameters, the TFTP server’s address and
the Time of Day (TOD) server’s address.
The
CMAC_LOG_DHCP_ASSIGNED_IP_ADDRESS field indicates the IP address assigned from the DHCP
server to the Cisco uBR924 interface. The
TFTP server’s address. The
server’s address. The
CMAC_LOG_DHCP_TOD_SERVER_ADDRESS field indicates the time of day
CMAC_LOG_DHCP_CONFIG_FILE_NAME f ield sho ws the f ilename containing the
transmission parameters. The
successful.
508175.968 CMAC_LOG_STATE_CHANGE dhcp_state
508176.982 CMAC_LOG_DHCP_ASSIGNED_IP_ADDRESS 188.188.1.62
508176.984 CMAC_LOG_DHCP_TFTP_SERVER_ADDRESS 4.0.0.1
508176.986 CMAC_LOG_DHCP_TOD_SERVER_ADDRESS 4.0.0.32
508176.988 CMAC_LOG_DHCP_SET_GATEWAY_ADDRESS
508176.988 CMAC_LOG_DHCP_TZ_OFFSET 360
508176.990 CMAC_LOG_DHCP_CONFIG_FILE_NAME platinum.cm
508176.992 CMAC_LOG_DHCP_ERROR_ACQUIRING_SEC_SVR_ADDR
508176.996 CMAC_LOG_DHCP_COMPLETE
Event 6—Establish the Time of Day
The Cisco uBR924 cable access router accesses the Time of Day server for the current date and time,
which is used to create time stamps for logged events. The
a successful time of day sequence.
508177.120 CMAC_LOG_STATE_CHANGE establish_tod_state
508177.126 CMAC_LOG_TOD_REQUEST_SENT
508177.154 CMAC_LOG_TOD_REPLY_RECEIVED 3107617539
508177.158 CMAC_LOG_TOD_COMPLETE
CMAC_LOG_DHCP_TFTP_SERVER_ADDRESS field marks the
CMAC_LOG_DHCP_COMPLETE field shows that the IP connectivity was
CMAC_LOG_TOD_COMPLETE field indicates
Event 7—Establish Security
The Cisco uBR924 establishes a security association. The security_association_state is
normally bypassed since “full security” as defined by DOCSIS is not supported.
Note “Full security” was a request made by MSOs for a very strong authorization and
authentication check by the CMTS. This request has not been granted by cable modem
manufacturers. The Cisco uBR924 supports DOCSIS baseline privacy beginning with Cisco IOS
Release 12.0(5)T, which protects user’s data from being “sniffed” on the cable network. For
information on baseline privacy, refer to “Event 10—Comply with Baseline Privacy” on page 17.
508177.160 CMAC_LOG_STATE_CHANGE security_association_state
508177.162 CMAC_LOG_SECURITY_BYPASSED
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Step 4—Interpret the MAC Log File and Take Action
Event 8—Transfer Operational Parameters
After the DHCP and security operations are successful, the Cisco uBR924 downloads operational
parameters via a configuration file located on the cable company’s TFTP server. The
CMAC_LOG_DHCP_CONFIG_FILE_NAME field shows the filename containing the transmission
parameters.
508177.164 CMAC_LOG_STATE_CHANGE configuration_file_state
508177.166 CMAC_LOG_LOADING_CONFIG_FILE platinum.cm
508178.280 CMAC_LOG_CONFIG_FILE_PROCESS_COMPLETE
Event 9—Perform Registration
After the Cisco uBR924 is initialized, authenticated, and configured, it requests to be registered with
the headend CMTS. The
number and a service ID (SID). Multiple CoS entries in the configuration file imply that multiple
SIDs are supported by the cable access router. If several cable access routers use the same
configuration file, they will have the same CoS numbers but will be assigned different SIDs.
CMAC_LOG_COS_ASSIGNED_SID field assigns a class of service (CoS)
A successful registration is indicated by the
508178.300 CMAC_LOG_STATE_CHANGE registration_state
508178.302 CMAC_LOG_REG_REQ_MSG_QUEUED
508178.306 CMAC_LOG_REG_REQ_TRANSMITTED
508178.310 CMAC_LOG_REG_RSP_MSG_RCVD
508178.312 CMAC_LOG_COS_ASSIGNED_SID 5/19
508178.314 CMAC_LOG_COS_ASSIGNED_SID 6/20
508178.316 CMAC_LOG_COS_ASSIGNED_SID 7/21
508178.318 CMAC_LOG_RNG_REQ_QUEUED 19
508178.320 CMAC_LOG_REGISTRATION_OK
CMAC_LOG_REGISTRATION_OK field.
Event 10—Comply with Baseline Privacy
Keys for baseline priv acy are exchanged between the Cisco uBR924 and the headend CMTS. During
this event, a link level encryption is performed so that a user’s data cannot be “sniffed” by anyone
else who is on the cable network.
Following is a trace that shows baseline privacy enabled. The key management protocol is
responsible for exchanging two types of keys: KEKs and TEKs. The KEK (key exchange key, also
referred to as the authorization key) is used by the headend CMTS to encrypt the TEKs (traffic
encryption keys) it sends to the Cisco uBR924. The TEKs are used to encrypt/decrypt the data. There
is a TEK for each SID that is configured to use privacy.
851.088 CMAC_LOG_STATE_CHANGE establish_privacy_state
851.094 CMAC_LOG_PRIVACY_FSM_STATE_CHANGE machine: KEK, event/state:
EVENT_1_PROVISIONED/STATE_A_START, new state: STATE_B_AUTH_WAIT
851.102 CMAC_LOG_BPKM_REQ_TRANSMITTED
851.116 CMAC_LOG_BPKM_RSP_MSG_RCVD
851.120 CMAC_LOG_PRIVACY_FSM_STATE_CHANGE machine: KEK, event/state:
EVENT_3_AUTH_REPLY/STATE_B_AUTH_WAIT, new state: STATE_C_AUTHORIZED
856.208 CMAC_LOG_PRIVACY_FSM_STATE_CHANGE machine: TEK, event/state:
EVENT_2_AUTHORIZED/STATE_A_START, new state: STATE_B_OP_WAIT
856.220 CMAC_LOG_BPKM_REQ_TRANSMITTED
856.224 CMAC_LOG_BPKM_RSP_MSG_RCVD
856.230 CMAC_LOG_PRIVACY_FSM_STATE_CHANGE machine: TEK, event/state:
EVENT_8_KEY_REPLY/STATE_B_OP_WAIT, new state: STATE_D_OPERATIONAL
856.326 CMAC_LOG_PRIVACY_INSTALLED_KEY_FOR_SID 2
856.330 CMAC_LOG_PRIVACY_ESTABLISHED
Note In order for baseline privacy to wo rk, you must use a code image name on the Cisco uBR924
that contains the characters k1. In addition, baseline privacy must be supported on the headend
CMTS, and it must be turned on in the configuration file that is downloaded to the Cisco uBR924.
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 17
Step 5—Use Additional Troubleshooting Commands
Event 11—Enter the Maintenance State
As soon as the Cisco uBR924 has successfully completed the above events, it enters the operational
maintenance state and is authorized to forward traffic into the cable network.
508178.322 CMAC_LOG_STATE_CHANGE maintenance_state
Step 5—Use Additional Troubleshooting Commands
You can use other show controllers and debug cable modem commands to troubleshoot different
aspects of a Cisco uBR924 cable access router. However, the most useful command is the show
controllers cable-modem 0 mac command.
To display additional con tro ller info rmation inside a Cisco uBR924, enter one or more of the
following commands in privileged EXEC mode:
Command Purpose
show controllers cable-modem Displays high-level controller information.
show controllers cable-modem bpkm Displays privacy state information.
show controllers cable-modem des Displays information about the Data Encryption
Standard (DES) engine registers.
show controllers cable-modem filters Displays information about the MAC and SID filters.
show controllers cable-modem lookup-table Displays the Cisco uBR924’s intern al mini-slot lookup
table.
show controllers cable-modem mac
log | resets | state]
show controllers cable-modem phy Displays physical-layer information such as recei ve and
show controllers cable-modem tuner Displays tuning information.
show interface cable-modem Displays information about the Cisco uBR924
[errors | hardware |
Displays detailed MAC-layer information.
transmit physical registers.
interface.
To debug different components of a Cisco uBR924, enter one or more of the following commands
in privileged EXEC mode:
Command Purpose
debug cable-modem bpkm
debug cable-modem bridge Debugs the bridge filter.
debug cable-modem error Debugs cable interface errors.
debug cable-modem interrupts Debugs Cisco uBR924 interface interrupts.
debug cable-modem mac
debug cable-modem map Debugs map message processing information.
Cisco IOS Release 12.0(5)T
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{errors | events | packets} Debugs baseline privacy information.
{log [verbose] | messages} Displays and debugs the MAC-lay er log entries in
real time.
Command Reference
This section describes the commands used in Cisco IOS Release 12.0(5)T for troubleshooting the
cable side of the Cisco uBR924 cable access router.
The commands used to troubleshoot VoIP applications are documented in the Cisco IOS
Release 12.0 command references.
• show controllers cable-modem
• show controllers cable-modem bpkm
• show controllers cable-modem des
• show controllers cable-modem filters
• show controllers cable-modem lookup-table
• show controllers cable-modem mac
• show controllers cable-modem phy
• show controllers cable-modem tuner
In Cisco IOS Release 12.0(1)T or later, you can search and filter the output for show and more
commands. This functionality is useful when you need to sort through large amounts of output, or if
you want to exclude output that you do not need to see.
Step 5—Use Additional Troubleshooting Commands
To use this functionality, enter a show or more command followed by the “pipe” character (|), one
of the keywords begin, include, or exclude, and an expression that you want to search or filter on:
command | {begin | include | exclude} regular-expression
Following is an example of the show atm vc command in which you want the command output to
begin with the first line where the expression “PeakRate” appears:
show atm vc | begin PeakRate
For more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T
feature module titled CLI String Sear ch.
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 19
show controllers cable-modem
show controllers cable-modem
T o display high-lev el controller information about a Cisco uBR924 cable access router, use the show
controllers cable-modem command in privileged EXEC mode.
show controllers cable-modem number
Syntax Description
number Controller number inside the Cisco uBR924.
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
Release Modification
11.3 NA This command was first introduced.
The show controllers cable-modem display begins with information from the first fe w re gisters of
the Broadcom BCM3300 chip. Next is buffer information for the receive, receive MAC message,
buffer descriptor, and packet descriptor rings. Then comes MIB statistics from the BCM3300 chip,
DMA base registers to indicate where the rings start, global control and status information, and
finally interrupts for the interrupt code.
When using this command, be sure to check the tx_count and the tx_head and tx_tail values for the
buffer descriptor (TX BD) and packet descriptor (TX PD) rings. The tx_count should be greater than
0, and the tx_head and tx_tail values should not be equal. If these values do not change for a long
period of time, it indicates there are packets stuck on the ring. This condition is often caused by the
headend not giving grants.
Cisco IOS Release 12.0(5)T
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Examples
show controllers cable-modem
Following is sample output for the show controllers cable-modem 0 command:
uBR924# show controllers cable-modem 0
BCM Cable interface 0:
BCM3300 unit 0, idb 0x200EB4, ds 0x82D4748, regaddr = 0x800000, reset_mask 0x80
station address 0010.7b43.aa01 default station address 0010.7b43.aa01
PLD VERSION: 32
MAC State is ranging_2_state, Prev States = 7
MAC mcfilter 01E02F00 data mcfilter 01000000
DS: BCM 3116 Receiver: Chip id = 2
US: BCM 3037 Transmitter: Chip id = 30B4
Tuner: status=0x00
Rx: tuner_freq 699000000, symbol_rate 5055849, local_freq 11520000
snr_estimate 33406, ber_estimate 0, lock_threshold 26000
QAM in lock, FEC in lock, qam_mode QAM_64
Tx: tx_freq 20000000, power_level 0x3E, symbol_rate 1280000
DHCP: TFTP server = 4.0.0.32, TOD server = 4.0.0.188
Security server = 0.0.0.0, Timezone Offest = 0.0.4.32
Config filename =
buffer size 1600
RX data PDU ring with 32 entries at 0x201D40
rx_head = 0x201D78 (7), rx_p = 0x831BE04 (7)
00 pak=0x8326318 buf=0x225626 status=0x80 pak_size=0
01 pak=0x83241A0 buf=0x21DE5A status=0x80 pak_size=0
02 pak=0x83239C0 buf=0x21C22A status=0x80 pak_size=0
03 pak=0x8328C70 buf=0x22EA22 status=0x80 pak_size=0
04 pak=0x8325F28 buf=0x22480E status=0x80 pak_size=0
05 pak=0x8327CB0 buf=0x22B1C2 status=0x80 pak_size=0
06 pak=0x8323BB8 buf=0x21C936 status=0x80 pak_size=0
RX MAC message ring with 8 entries at 0x201E80
rx_head_mac = 0x201E88 (1), rx_p_mac = 0x831BE80 (1)
00 pak=0x8326120 buf=0x224F1A status=0x80 pak_size=0
01 pak=0x8324590 buf=0x21EC72 status=0x80 pak_size=0
02 pak=0x8323FA8 buf=0x21D74E status=0x80 pak_size=0
03 pak=0x8326EE8 buf=0x22806E status=0x80 pak_size=0
04 pak=0x8328E68 buf=0x22F12E status=0x80 pak_size=0
05 pak=0x8327AB8 buf=0x22AAB6 status=0x80 pak_size=0
06 pak=0x8328880 buf=0x22DC0A status=0x80 pak_size=0
07 pak=0x8326CF0 buf=0x227962 status=0xA0 pak_size=0
TX BD ring with 8 entries at 0x201FB8, tx_count = 0
tx_head = 0x201FD8 (4), head_txp = 0x831BF20 (4)
tx_tail = 0x201FD8 (4), tail_txp = 0x831BF20 (4)
00 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
01 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
02 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
03 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
04 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
05 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
06 pak=0x000000 buf=0x200000 status=0x00 pak_size=0
07 pak=0x000000 buf=0x200000 status=0x20 pak_size=0
TX PD ring with 8 entries at 0x202038, tx_count = 0
tx_head_pd = 0x202838 (4)
tx_tail_pd = 0x202838 (4)
00 status=0x00 bd_index=0x0000 len=0x0000 hdr_len=0x0000
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 21
show controllers cable-modem
ehdr: 01 06 02 74 34 11
01 status=0x00 bd_index=0x0001 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
02 status=0x00 bd_index=0x0002 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
03 status=0x00 bd_index=0x0003 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
04 status=0x00 bd_index=0x0004 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
05 status=0x00 bd_index=0x0005 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
06 status=0x00 bd_index=0x0006 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
07 status=0x20 bd_index=0x0007 len=0x0000 hdr_len=0x0000
ehdr: 01 06 02 74 34 11
MIB Statistics
DS fifo full = 0, Rerequests = 0
DS mac msg overruns = 0, DS data overruns = 0
Qualified maps = 348, Qualified syncs = 73
CRC fails = 0, HDR chk fails = 0
Data pdus = 0, Mac msgs = 423
Valid hdrs = 423
BCM3300 Registers:
downstream dma:
ds_data_bd_base=0x001D40, ds_mac_bd_base=0x001E80
ds_data_dma_ctrl=0x98, ds_mac_dma_ctrl=0xD8
ds_dma_data_index=0x0007, ds_dma_msg_index=0x0000
upstream dma:
us_bd_base=0x001FB8, us_pd_base=0x002038
us_dma_ctrl=0x80, us_dma_tx_start=0x00
Global control and status:
global_ctrl_status=0x00
interrupts:
irq_pend=0x0008, irq_mask=0x00F7
Cisco IOS Release 12.0(5)T
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Table 2 briefly describes some of the fields shown in the display. For more information, see the
Broadcom documentation for the BCM3300 chip.
Table 2 Show Controllers Cable-Modem Field Descriptions
Field Description
BCM3300 unit The unit number of this BCM3300 chip.
idb Interface description block number.
ds Downstream channel.
regaddr Indicates the start of the BCM3300 registers.
reset_mask Indicates the bit to hit when resetting the chip.
station address MAC address of this Cisco uBR924 cable access router interface.
default station address Default MAC address assigned by the factory for this Cisco uBR924 cable access
router.
PLD VERSION PLD version of the BCM3300 chip.
MAC state Current MAC state of the Cisco uBR924.
Prev States Number of states that have previously existed since initialization.
MAC mcfilter MAC control filter for MAC messages.
show controllers cable-modem
Table 2 Show Controllers Cable-Modem Field Descriptions (continued)
Field Description
data mcfilter MAC control filter for data.
DS Downstream Broadcom receiver chip number and ID.
US Upstream Broadcom transmitter chip number and ID.
Tuner: status Current status of the tuner.
Rx: tuner_freq Downstream frequency (in Hz) that the Cisco uBR924 searched for and found.
symbol_rate Downstream frequency in symbols per second.
local_freq Frequency on which the transmitter and the tuner communic at e.
snr_estimate Estimate of signal-to-noise ratio (SNR) in Db X 1000.
ber_estimate E st imate of bit error rate (always 0).
lock_threshold Minimum signal-to-noise ratio (SNR) that the Cisco uBR924 will accept as a valid lock.
qam_mode The modulation scheme used in the downstream direction.
Tx: tx_freq Upstream frequency sent to the Cisco uBR924 by the CMTS in the UCD message.
power_level Transmit power level as set in the hardware, expressed as a hexadecimal value. The
units are unique to the hardware used. Use the show controllers cable-modem 0 mac
state command to see the power level in dBmV.
symbol_rate Upstream frequency in symbols per second.
TFTP server IP address of the TFTP server at the headend.
TOD server IP address of the time-of-day server at the headend.
Security server IP address of the security server at the headend.
Timezone Offset Correction received from the DHCP server to synchronize the Cisco uBR924 time clock
with the CMTS.
Config filename Name of the file stored on the cable company’s TFTP server that contains operational
parameters for the Cisco uBR924.
buffer size Size in bytes of the BCM3300 message buffers.
RX data PDU ring:
rx_head
rx_p
RX MAC message ring:
rx_head_mac
rx_p_mac
TX BD ring:
tx_count
tx_head
head_txp
Indicates the memory location of the beginning of buffer information for the receive
data ring.
Indicates current head buffer descriptor.
Indicates current head packet descriptor.
Indicates the memory location of the beginning of buffer information for the receive
MAC message ring.
Indicates current head buffer descriptor.
Indicates current head packet descriptor.
Indicates the memory location of the beginning of buffer information for the transmit
buffer descriptor ring.
If tx_count is 0, or if tx_head and tx_tail are equal and there is no change for a period of
time, it means there are packets stuck on the ring. This condition may be caused by the
headend not giving grants.
The next packet descriptor to get used, along with its index.
tx_tail
tail_txp
The next packet descriptor to get sent, along with its index. When head_txp and tail_txp
are the same, the transmit queue is empty.
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 23
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