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Cisco IOS CMTS Cable Command Reference
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Cisco IOS CMTS Cable Command Reference Title
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Introduction
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Cable Commands: a through cable-modem
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Cable Commands: cable a through cable c
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Cable Commands: cable d
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Cable Commands: cable e through cable i
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Cable Commands: cable l
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Cable Commands: cable m
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Cable Commands: cable p through cable r
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Cable Commands: cable s
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Cable Commands: cable t
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Cable Commands: cable u through cable w
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Cable Commands: ca through cr
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Cable Commands: d through h
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Cable Commands: i through p
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Cable Commands: q through sg
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Cable Commands: show a through show cable l
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Cable Commands: show cable m through show cable t
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Cable Commands: show ch through show cr
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Cable Commands: show d through show i
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Cable Commands: show m through show z
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Cable Commands: snmp through w
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Appendix A: Cable Debug Commands
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Appendix B: Cisco CMTS Router ROM Monitor Commands
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Table Of Contents
Cable Commands: cable u through cable w
cable upstream admission-control
cable upstream differential-encoding
cable upstream equalization-coefficient
cable upstream equalization-error-recovery
cable upstream freq-adj averaging
cable upstream ingress-noise-cancellation
cable upstream load-balance group
cable upstream modulation-profile
cable upstream rate-adapt (global)
cable upstream rate-adapt (interface)
cable upstream scheduling type
cable upstream threshold hysteresis
cable upstream unfrag-slot-jitter
Cable Commands: cable u through cable w
Revised: March 30, 2009, OL-15510-09
New Commands
Modified Commands
cable wideband auto-reset
12.3(23)BC
cable upstream modulation
12.3(23)BC7
cable upstream admission-control
To specify the percentage overbooking rate that is allowed on an upstream channel, use the cable upstream admission-control command in cable interface configuration mode. To set overbooking rate to its default of 100 percent, use the no form of this command.
cable upstream n admission-control percentage
no cable upstream n admission-control
Syntax Description
Command Default
100 percent
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command limits the maximum number of CMs for a given upstream port by looking at the minimum guaranteed upstream bandwidth allocated to each CM. Cable modems providing residential services and commercial services can be given different weights according to their traffic needs. This command affects only whether CMs can register with the CMTS—it does not affect CMs that have already come online.
The CMTS uses the minimum guaranteed upstream bandwidth field from the CM's DOCSIS configuration file to calculate whether the CM can come online or not. If the CM's minimum guaranteed upstream bandwidth would exceed the total upstream bandwidth multiplied by the overbooking percentage specified by this command, the CM cannot come online on that upstream. The CM will attempt to find another upstream, and if it cannot register on any upstreams, it will attempt to lock on to a new downstream.
Note
A CM with a guaranteed upstream bandwidth does not consume that bandwidth unless it has active traffic. By guaranteeing a CM a minimum upstream bandwidth, individual customers are assured of never being totally shut out from network access in a very high-traffic situation.
Table 0-1 shows the approximate bandwidth for each upstream channel, depending on channel width, symbol rate, and modulation type, when admission control is used at 100 percent. When setting admission control to other values, scale the bandwidth values in Table 0-1 accordingly, so as to plan for the maximum number of CMs effectively allowed per upstream port.
For example, with a 3.2 MHz channel width and QPSK modulation, the total bandwidth is approximately 5 Mbps. This is the maximum allowable bandwidth that can be allocated to CMs at the default admission rate of 100%. If each CM is allocated a minimum upstream bandwidth of 128 kbps, this means a maximum of 40 CMs will be allowed to come online.
To verify whether or not upstream admission control is configured and activated, use the show interface command for a cable upstream to display its configuration information. If upstream admission control is configured and enabled, the output contains an entry stating "CIR admission control enforced." If upstream admission control is disabled, no admission control entry is displayed in the output.
Note
When an upstream becomes overbooked, use the test cable ucc command to move a cable modem that is currently online from one upstream port to another. For example, the following example shows that the cable modem with the IP address of 10.128.1.128 is being moved from port C3/0/U0 to C3/0/U1:
Router# show cable modem 10.128.1.128Interface Prim Online Timing Rec QoS CPE IP address MAC addressSid State Offset PowerCable3/0/U0 101 online 1919 5.25 7 0 10.128.1.128 0030.1976.7067Router# test cable ucc c3/0 101 1Router# show cable modem 10.128.1.128Interface Prim Online Timing Rec QoS CPE IP address MAC addressSid State Offset PowerCable3/0/U1 101 online 1920 5.25 7 0 10.128.1.128 0030.1976.7067Examples
The following example shows overbooking on upstream port 4 being limited to 125 percent:
Router(config)# interface cable 3/0Router(config-if)# cable upstream 4 admission-control 125Router(config-if)#Use the show interface cable upstream command to display the current status of admission control on an interface. For example, the following command output shows that this upstream has allocated a total bandwidth of 2.5 Mbit/sec to those online CMs that were assigned a guaranteed upstream bandwidth in their DOCSIS configuration files.
This displays also shows that the admission control is being enforced at a subscription level of 125 percent. The Virtual channel BW field is computed by multiplying channel bandwidth by the admission control limit. The Admissions requests rejected counter shows the number of cable modems that attempted to register but were refused because of the admission control policy.
Router# show interface c3/0 u4Cable3/0: Upstream 4 is upReceived 11585 broadcasts, 11854 multicasts, 3222651 unicasts0 discards, 829 errors, 0 unknown protocol3246090 packets input, 5 uncorrectable557 noise, 0 microreflectionsTotal Modems On This Upstream Channel : 69 (68 active)Default MAC schedulerQueue[Rng Polls] 0/64, fifo queueing, 0 dropsQueue[Cont Mslots] 0/52, fifo queueing, 0 dropsQueue[CIR Grants] 0/64, fair queueing, 0 dropsQueue[BE Grants] 0/64, fair queueing, 0 dropsQueue[Grant Shpr] 0/64, calendar queueing, 0 dropsReserved slot table currently has 0 CBR entriesReq IEs 205196036, Req/Data IEs 0Init Mtn IEs 7604617, Stn Mtn IEs 422496Long Grant IEs 4848, Short Grant IEs 1646196Avg upstream channel utilization : 1%Avg percent contention slots : 94%Avg percent initial ranging slots : 1%Avg percent minislots lost on late MAPs : 0%Total channel bw reserved 2500000 bpsCIR admission control enforcedSubscribtion level 125%Virtual channel bw 6400000 bpsAdmission requests rejected 32Current minislot count : 5200298 Flag: 0Scheduled minislot count : 5200420 Flag: 0Router#If a CM is denied access due to the admission control policy, its entry in the show cable modem command output shows "reject(c)":
Router# show cable modemInterface Prim Online Timing Rec QoS CPE IP address MAC addressSid State Offset PowerCable2/0/U0 1 online 2288 0.50 4 0 10.16.30.66 0010.7bb3.fb45Cable2/0/U0 2 online 2288 0.50 4 0 10.16.30.68 0010.7bb3.fb7bCable2/0/U0 3 init(i) 2280 0.00 2 0 10.16.30.69 0010.9500.05e. . .Cable3/0/U1 113 online 3921 0.00 5 0 10.128.1.108 0030.9433.c38bCable3/0/U1 114 online 3920 0.25 6 0 10.128.1.87 0030.1976.6ebfCable3/0/U0 115 reject(c) 3922 0.25 2 0 10.128.1.75 0030.1976.703bCable3/0/U0 116 online 3919 0.75 5 0 10.128.1.57 0030.1976.6fa1Related Commands
cable upstream attribute-mask
To specify an upstream attribute mask in hexadecimal format, use the cable upstream attribute-mask command in cable interface configuration mode. Use the no form of this command to set default value to upstream channel attribute mask.
cable upstream upstream attribute-mask attribute-mask
no cable upstream upstream attribute-mask attribute-mask
Syntax Description
upstream
Specifies the upstream port.
attribute-mask attribute-mask
Specifies the attribute mask bitmap in hexadecimal format.
Example: 0-FFFFFFFF
Command Default
The default value of upstream channel attribute mask is 0.
Command Modes
Interface configuration—cable interface only (config-if)
Command History
Usage Guidelines
This command sets the attribute mask of upstream channel.
Examples
The following example shows how to set upstream attribute mask in hexadecimal format:
Router(config-if)# cable upstream 0 attribute-mask ffffRelated Commands
clear cable modem attribute-masks
This command clears the cable modem attribute masks.
cable upstream channel-width
To specify an upstream channel width for an upstream port, use the cable upstream channel-width command in cable interface configuration mode. To set the channel width back to the default setting of 1,600,000 Hz, use the no form of this command.
cable upstream n channel-width first-choice-width [last-choice-width]
no cable upstream n channel-width
Syntax Description
Command Default
The first-choice-width value and the last-choice-width value default to 1,600,000 Hz.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The last-choice-width parameter is supported only by the Cisco uBR-MC16S, Cisco uBR-MC16U/X, Cisco uBR-MC28U/X, and Cisco uBR-MC5X20S/U cable interface line cards. When one of these particular cards is installed, the system attempts to increase the channel width from the smallest channel width value to the largest channel width value.
When you specify both channel width values, the smaller value is taken as the last-choice-width parameter and the larger value is taken as the first-choice-width parameter. In the event of noise in the channel, the symbol rate automatically steps down to a value that is lower than the first-choice-width and greater or equal to the last-choice-width to maintain a stable channel.
Note
Caution
Note
cable upstream 0 channel-width 800000 800000When using this command to change channel-widths for an upstream interface on the Cisco uBR-MC5X20S cable interface line card, some DOCSIS 1.1 CMs can go offline if you do not also change the minislot size to the corresponding value. See the following examples for the correct channel-width and minislot pairings:
Router(config-if)# cable upstream 0 channel-width 3200000Router(config-if)# cable upstream 0 minislot 4Router(config-if)# cable upstream 0 channel-width 1600000Router(config-if)# cable upstream 0 minislot 8Router(config-if)# cable upstream 0 channel-width 800000Router(config-if)# cable upstream 0 minislot 16Router(config-if)# cable upstream 0 channel-width 400000Router(config-if)# cable upstream 0 minislot 32Router(config-if)# cable upstream 0 channel-width 200000Router(config-if)# cable upstream 0 minislot 64
Note
PacketCable Limitations
The 200,000 Hz channel width cannot be used on upstreams that support PacketCable voice calls, or on any upstreams that use Unsolicited Grant Service (UGS) or UGS with Activity Detection (UGS-AD) service flows. Using this small a channel width with voice and other UGS/UGS-AD service flows results in calls being rejected because of "DSA MULTIPLE ERRORS".
Examples
The following example shows upstream port 2 on a Cisco uBR-MCXXC card being configured with a channel width of 200,000 Hz (which is equivalent to a symbol rate of 160 kilosymbols/second):
Router(config-if)# cable upstream 2 channel-width 200000Router(config-if)#The following example shows upstream port 2 on a Cisco uBR-MC16S, Cisco uBR-MC16U/X, Cisco uBR-MC28U/X, or Cisco uBR-MC5X20S card being configured with a channel width of 200,000 Hz (which is equivalent to a symbol rate of 160 kilosymbols/second):
Router(config-if)# cable upstream 2 channel-width 200000 200000Router(config-if)#The following example shows upstream port 3 being configured to step from a channel width of 1,600,000 Hz to a channel width of 3,200,000 Hz in increments of 200,000 Hz:
Router(config-if)# cable upstream 3 channel-width 1600000 3200000Router(config-if)#The following example shows an upstream port on a Cisco uBR-MC16U/X, Cisco uBR-MC28U/X, or Cisco uBR-MC5X20S card being configured with a channel width of 6.4 MHz, which is supported only in DOCSIS 2.0 A-TDMA-only mode:
Router(config-if)# cable upstream 0 channel-width 6400000Router(config-if)#Related Commands
cable upstream concatenation
To enable DOCSIS concatenation at the CMTS, use the cable upstream concatenation command in cable interface configuration mode. To turn off concatenation, use the no form of this command.
cable upstream n concatenation
no cable upstream n concatenation
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Concatenation is enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
Concatenation is part of DOCSIS 1.0 extension support. Concatenation provides for improved bandwidth efficiency but must be supported at both the headend CMTS and the CM.
DOCSIS concatenation combines multiple upstream packets into one packet to reduce packet overhead and overall latency and increase transmission efficiency. Using concatenation, a DOCSIS CM needs to make only one bandwidth request for a concatenated packet, compared to making bandwidth requests for each individual packet. This technique is especially effective for bursty real-time traffic such as voice calls.
Concatenation support improves upstream per CM data throughput. The Cisco CMTS radio frequency (RF) line card driver can receive only one MAC frame in a data burst. Thus the CM must make explicit bandwidth requests for every packet it sends upstream. This limits the maximum upstream data throughput received by the CM due to the inherent request-to-grant round-trip latency of the hybrid fiber-coaxial (HFC) cable system incurred by every packet. To increase this per-CM upstream throughput, the Cisco CMTS driver has been enhanced to receive a concatenated burst of multiple MAC frames from the same CM.
Note
Examples
The following example shows how to enable concatenation for CMs on upstream port 2 on the cable interface in slot 3/0:
Router(config)# interface c3/0Router(config-if)# cable upstream 2 concatenationcable upstream connector
To map an upstream port to a physical port on the Cisco uBR-MC5X20S/U cable interface line card for use with a particular downstream, use the cable upstream connector command in cable interface configuration mode. To remove the mapping and shut down the upstream port, use the no form of this command.
cable upstream logical-port connector physical-port
no cable upstream logical-port connector physical-port
Syntax Description
logical-port
Specifies the upstream port number for the logical port assignment. The number of logical ports is configured with the cable modulation-profile command, and the valid range is from 0 to one less than the current value set with the cable modulation-profile command.
Tipphysical-port
Specifies the upstream port number for the actual physical port to be assigned. The valid range is 0 to 19, with no default.
Defaults
By default, the Cisco uBR-MC5X20S/U cable interface line card uses a fixed configuration, in which each downstream is allocated four upstream ports.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The cable upstream connector command changes the default assignment of upstream ports to MAC domains on the Cisco uBR-MC5X20S/U card. This command creates a virtual upstream for a downstream and assigns it to a particular physical port.
The default port mapping assigns four upstream ports to each of the downstream ports (MAC domains). The ports are assigned sequentially, in the order in which they appear on the card's front panel.
The no version of this command removes the upstream port mapping and shuts down the upstream port. The port must be remapped to another physical port before it can come online again.
Tip
Table 12 shows the default port mapping.
The physical upstream ports can be assigned in any combination to a downstream, up to a maximum of 8 upstreams per downstream. If you have previously mapped an upstream port to a physical port using the cable upstream connector command, you must first remove that mapping, using the no form of the command, before changing it.
Examples
The following example shows how to configure a downstream (MAC domain) on the Cisco uBR-MC5X20S card for 8 upstream ports:
Router# configure terminalRouter(config)# interface cable c8/1/0Router(config-if)# cable upstream max-ports 8Router(config-if)# cable upstream 0 connector 16Router(config-if)# cable upstream 1 connector 17Router(config-if)# cable upstream 2 connector 18Router(config-if)# cable upstream 3 connector 12Router(config-if)# cable upstream 4 connector 13Router(config-if)# cable upstream 5 connector 14Router(config-if)# cable upstream 6 connector 15Router(config-if)# cable upstream 7 connector 11Router(config-if)# exitRouter(config)# exitRouter#Related Commands
Configures the maximum number of upstreams on a downstream (MAC domain) on a Cisco uBR-MC5X20S cable interface line card.
cable upstream data-backoff
To specify automatic or fixed start and stop values for data backoff, use the cable upstream data-backoff command in cable interface configuration mode. To use the default data backoff values, use the no form of this command.
cable upstream n data-backoff {automatic | start end}
no cable upstream n data-backoff
Syntax Description
Command Default
Automatic
Command Modes
Interface configuration (cable interface only)
Command History
12.1 T
This command was introduced.
12.1(5)EC1
Support was added for the Cisco uBR7100 series router.
12.2(4)BC1
Support was added for the Cisco uBR10012 router.
Usage Guidelines
The DOCSIS-specified method of contention resolution for CMs used to send data or requests on the upstream channel is a truncated binary exponential backoff with the initial backoff window and the maximum backoff window controlled by the CMTS. The Cisco CMTS router specifies backoff window values for both data and initial ranging, and sends these values downstream as part of the Bandwidth Allocation Map (MAP) MAC message.
The values specified in this command are exponential power-of-two values. For example, a value of 4 indicates a window between 0 and 15; a value of 10 indicates a window between 0 and 1023.
Cisco recommends that you use the automatic settings for data backoff. If you decide to manually specify the data-backoff values, use the following formula as a guideline for the start and end binary exponents:
0.33 = (2**stop - 2**start)/nwhere n is the number of CMs on the upstream. Choose start and stop values that come closest to the value of 0.33 (which is the optimal probability to transmit on a contention-based system).
Examples
The following example shows how to set the automatic data backoff values for upstream 2 on a cable interface card:
Router# configure terminalRouter(config)# interface cable 3/0Router(config-if)# cable upstream 2 data-backoff automaticRouter(config-if)#Related Commands
cable upstream description
To assign a label to an upstream, use the cable upstream description command in cable interface configuration mode. To remove the label from the upstream, use the no form of this command.
cable upstream n description label
no cable upstream n description
Syntax Description
Command Default
No description is assigned to upstreams
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
Use the cable upstream description command to assign arbitrary labels to the upstreams on the cable interfaces. These labels can contain any information that identifies the upstream and that could aid in network management or troubleshooting.
Tip
Examples
The following example shows how to assign descriptions to the first two upstreams on the cable interface in slot 3:
Router# configure terminalRouter(config)# interface cable 3/0Router(config-if)# cable upstream 0 description "SJ-Node1-Upstream 0"Router(config-if)# cable upstream 1 description "SJ-Node1-Upstream 1 (Unused)"Router(config-if)#Related Commands
show interface cable
Displays the current configuration and status of a cable interface.
cable upstream differential-encoding
To enable differential encoding on upstream traffic to a specified cable interface, use the cable upstream differential-encoding command in cable interface configuration mode. To disable this function, use the no form of this command.
cable upstream n differential-encoding
no cable upstream n differential-encoding
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
To verify whether or not upstream differential encoding is activated, enter the show running-config command and look for the cable interface configuration information. If upstream differential encoding is enabled, a differential encoding entry is displayed in the output of the show running-config command. If upstream differential encoding is disabled, no differential encoding entry is displayed in the output.
If you are having trouble, make sure that the cable connections are not loose or disconnected; the cable interface line card is firmly seated in its chassis slot; the captive installation screws are tight; you have entered the correct slot and port numbers; and you selected a valid frequency for your router.
Examples
The following example shows how to enable differential encoding for upstream port 2:
Router(config-if)# cable upstream 2 differential-encodingRouter(config-if)#cable upstream docsis-mode
To configure an upstream to use either DOCSIS 1.x or DOCSIS 2.0 modulation profiles, use the cable upstream docsis-mode command in cable interface configuration mode. To reset the upstream to its default configuration, use the no form of this command.
cable upstream n docsis-mode {atdma | tdma | tdma-atdma}
no cable upstream n docsis-mode {atdma | tdma | tdma-atdma}
Syntax Description
Command Default
All upstreams are configured TDMA-only mode (DOCSIS 1.0/DOCSIS 1.1).
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The DOCSIS 2.0 specification provides support for advanced modulation profiles that increase potential upstream bandwidth by building on the existing TDMA support. The Advanced TDMA profiles support higher QAM rates up to 64-QAM and wider channel widths up to 6.4 MHz (5.12 Msymbols).
Note
The DOCSIS 2.0 specification allows an upstream to be configured in one of the following three modes:
•
Changing the DOCSIS mode to A-TDMA only mode also automatically changes the symbol rate to 5.12 megasymbols per second and the channel width to 6.4 MHz. Dynamic upstream modulation is also automatically disabled.
In addition, the following are required to support the DOCSIS 2.0 A-TDMA features:
–
–
–
•
Changing the DOCSIS mode to TDMA-only mode also automatically changes the symbol rate to 1.28 megasymbols per second and the channel width to 1.6 MHz. Dynamic upstream modulation is also automatically disabled.
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Changing the DOCSIS mode to mixed mode also automatically changes the symbol rate to 1.28 megasymbols per second and the channel width to 1.6 MHz. Dynamic upstream modulation is also automatically disabled.
Note
Changing the DOCSIS Mode for an Upstream Port Forces the Cable Modems on That Upstream to Go Offline and Reregister
When you switch the DOCSIS mode of an upstream between the TDMA-only, mixed TDMA/A-TDMA, and A-TDMA-only modes, cable modems that are currently online on that upstream are taken offline and are forced to reregister, so that the CMTS can determine the capabilities of the cable modems on the new channels.
If you change an upstream port to A-TDMA only mode, DOCSIS 1.x cable modems will not be able to come online on that upstream. If you change an upstream to TDMA only mode, DOCSIS 2.0-compliant cable modems are expected to attempt to come online on another upstream that is configured for A-TDMA or mixed mode. If no such upstreams are configured, or if the cable modem is configured to use only that particular upstream, it comes online in DOCSIS 1.x mode.
Note
If you change an upstream port to the mixed TDMA/A-TDMA mode, and some cable modems remain offline, or appear to come online but cannot pass traffic, upgrade the modem software to a DOCSIS-compliant software version.
Note
Examples
The following example shows how to configure the first four upstreams for the first downstream on the Cisco uBR-MC28U/X cable interface line card in slot 5/0. The first two upstreams are configured for A-TDMA mode and the last two upstreams are configured for mixed TDMA/A-TDMA mode.
Router# config terminalRouter(config)# interface cable 5/0/0Router(config-if)# cable upstream 0 docsis-mode atdma%%Docsis mode set to ATDMA only, 1.x CMs will go offline.%%The following defaults will be set:%%Channel Width 6.4MHz%%Minislot Size 1 tick%%Modulation Profile 241Router(config-if)# cable upstream 1 docsis-mode atdma%%Docsis mode set to ATDMA only, 1.x CMs will go offline.%%The following defaults will be set:%%Channel Width 6.4MHz%%Minislot Size 1 tick%%Modulation Profile 241Router(config-if)# cable upstream 2 docsis-mode tdma-atdma%%Docsis mode set to DOCSIS2.0 Mixed Mode.Router(config-if)# cable upstream 3 docsis-mode tdma-atdma%%Docsis mode set to DOCSIS2.0 Mixed Mode.Router(config-if)# exitRouter(config)# exitRouter#The following example shows the abbreviations needed to configure TDMA-only and mixed TDMA/A-TDMA modes.
Router# config terminalRouter(config)# interface cable 4/0Router(config-if)# cable upstream 0 docsis-mode tdm%%Docsis mode set to DOCSIS1.0 TDMA Mode.Router(config-if)# cable upstream 1 docsis-mode tdma-%%Docsis mode set to DOCSIS2.0 Mixed Mode.Router(config-if)#Related Commands
cable upstream equalization-coefficient
To enable the use of a DOCSIS 1.1 or 2.0 pre-equalization coefficient on an upstream port, use the cable upstream equalization-coefficient command in cable interface configuration mode. To disable the use of the pre-equalization coefficient, use the no form of this command.
cable upstream n equalization-coefficient
no cable upstream n equalization-coefficient
Syntax Description
n
Specifies the upstream port number. Valid range is from 0 to 7 for upstream ports in the cable interface line card.
Command Default
Pre-equalization coefficient is disabled.
Command Modes
Interface configuration (cconfig-if)
Command History
Usage Guidelines
The DOCSIS 1.1 and 2.0 specifications allow a CMTS to specify a pre-equalization coefficient in the DOCSIS ranging response (RNG-RSP) MAC management messages it forwards to the cable modems (CM)s. When this is enabled, a CM can engage in transmit-side equalization (pre-equalization) to mitigate the effects of certain impairments in the cable plant, such as in-channel tilt, and group delay.
These impairments are more significant with higher order modulation formats such as 64-QAM or 16-QAM, and near the first octave break-point of the diplex filters (34 MHz to 38 MHz). This break-point exists predominantly as a time-domain group delay issue, and becomes severe for longer amplifier cascades.
Each amplifier causes the DOCSIS upstream signal to traverse two diplex filters. All diplex filter frequency splits (5-42 MHz, 5-65 MHz, or 5-88 MHz) share this characteristic, which is not visible in a frequency response measurement or sweep test.
Note
DOCSIS 1.1 specifies the Type 4 type length value (TLV), and an 8-tap equalizer. DOCSIS 2.0 adds the Type 9 TLV, and increases the equalizer to support 24 taps to compensate for more complex impairments.
The cable upstream equalization-coefficient command configures the CMTS to send Type 4 TLV or Type 9 TLVs in the DOCSIS RNG-RSP MAC management messages to the CMs.
The no form of the command disables the CMTS from sending Type 4 TLV or Type 9 TLVs in the DOCSIS RNG-RSP MAC management messages to the CMs.
After the CMTS stops sending pre-equalization TLVs to the CM, the CM must retain these values until the modem's cable interface resets, or a modification is made to the upstream channel descriptor (UCD), which would make the stored equalization coefficients invalid.
Tip
•
•
Router# clear cable modem aaaa.bbbb.cccc resetYou can reset the equalizer coefficient of all CMs on an upstream by:
•
•
A CMTS operating in a pure DOCSIS 2.0 upstream mode sends equalizer data supporting 24 taps to all modems during initial ranging.
The cable up 0 docsis-mode atdma command configures a DOCSIS 2.0-only upstream mode on the CMTS.
A CMTS operating in a DOCSIS 1.1 or mixed TDMA-ATDMA upstream mode sends equalizer data supporting 8 taps to all modems during initial ranging. The CMTS cannot send data supporting 24 taps until it is notified by the CM, that it is DOCSIS 2.0 compliant in the Registration Request (REG-REQ) message, immediately preceding the online state.
This can be configured on the CMTS using the cable up 0 docsis-mode tdma-atdma command.
When a CM receives a Type 4 TLV in the RNG-RSP MAC management message from the CMTS, it must combine the previously stored values with the new values from the CMTS. Under certain HFC plant conditions, a dynamic impairment occurs that require the CM to adjust its main equalizer tap. The DOCSIS standard specifies a convolution function that is sometimes unable to adjust for dynamic impairments. The result, is a CM whose signal-to-noise ratio (SNR) value as received by the CMTS, is quite low compared to other CMs on the same upstream.
In a mixed modulation profile, where station maintenance is of a lower order modulation format than the data grants, it is possible for the modem to enter a steady state where the SNR estimate is:
•
•
This results in a modem that responds to DOCSIS Layer 2 pings, but not to Layer 3 traffic. The following commands can be used to check status:
•
•
A cable modem whose SNR estimate is in this condition may enter the expired(pt) state when baseline privacy interface plus (BPI+) is enabled. A modulation profile where station maintenance and data grants are of the same order modulation, prevents this condition.
The CMTS may be configured to enable cable upstream pre-equalization on a per upstream port basis, and may be configured to disable the sending of upstream equalization-coefficients on a per modem MAC address or Organizational Unique Identifier (OUI) basis, using the related global exclude commands.
Note
Some older DOCSIS cable modem firmware versions will incorrectly process the transition from 8 to 24 taps when in a mixed TDMA-ATDMA mode, and will experience degrading or low SNR MER as displayed with show cable modem phy command. Upgrade the CM firmware, and temporarily move these modems to a pure DOCSIS 1.1 or 2.0 channel or disable pre-equalization for these devices with the exclude command.
Examples
The example shows how to enable the use of the pre-equalization coefficient on upstream port 0 in the cable interface line card in slot 5/1 on the Cisco uBR10012 router, while excluding the equalization coefficient messaging to a modem with MAC address aaaa.bbbb.cccc, and all modems with the OUI of 00aa.bb:
Router# configure terminalRouter# cable pre-equalization exclude aaaa.bbbb.ccccRouter# cable pre-equalization exclude 00aa.bbRouter(config)# interface cable 5/1/0Router(config-if)# cable upstream 0 equalization-coefficientRouter(config-if)#Related Commands
cable upstream equalization-error-recovery
To enable the pre-equalizer direct load mechanism on an upstream port, use the cable upstream equalization-error-recovery command in cable interface configuration mode.
cable upstream port number equalization-error-recovery
no cable upstream port number equalization-error-recovery
Syntax Description
Command Default
This command is enabled by default.
Command Modes
Interface configuration (config-if)
Command History
Usage Guidelines
The pre-equalizer direct load mechanism is enabled by default. However, to use this direct load mechanism, you must enable the pre-equalization coefficient on an upstream port using the cable upstream equalization-coefficient command.
The cable upstream equalization-error-recovery command enables the CMTS to send Type-Length-Value (TLV) Type 9 in the DOCSIS RNG-RSP MAC management messages. This mechanism helps CMs come online when TLV Type 4 convolved method causes CMs to go offline.
Note
Examples
The example shows how to enable the pre-equalizer direct load mechanism on a cable interface line card in slot 8/0 on the Cisco uBR10012 router.
Router# configure terminalRouter(config)# interface cable 8/0/0Router(config-if)# cable upstream 0 equalization-error-recoveryRelated Commands
cable upstream fec
To enable upstream forward error correction (FEC), use the cable upstream fec command in cable interface configuration mode. To disable FEC, use the no form of this command.
cable upstream n fec
no cable upstream n fec
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The Cisco CMTS uses FEC to attempt to correct any upstream data that might have been corrupted. To use this feature, you need to activate FEC on the upstream RF carrier. When FEC is activated, the Cisco CMTS commands all CMs on the network to activate FEC.
Examples
The following example shows how to activate upstream forward error correction:
Router (config-if)# cable upstream 0 fecRelated Commands
cable upstream fec-strength
To override the forward error correction (FEC) setting specified in the modulation profile for this upstream channel, use the cable upstream fec-strength command in cable interface configuration mode. To restore the default value, use the no form of this command.
cable upstream n fec-strength t-bytes
no cable upstream n fec-strength
Syntax Description
Command Default
No default behavior or values
Command Modes
Interface configuration (cable interface only)
Command History
12.0(4)XI
This command was introduced.
12.1T
This command was deprecated and removed.
Examples
The following example shows how to configure the cable upstream fec-strength command:
Router(config-if)# cable upstream 2 fec-strength 3Related Commands
cable upstream fragmentation
To enable fragmentation of DOCSIS frames on a particular upstream, use the cable upstream fragmentation command in cable interface configuration mode. To disable fragmentation, use the no form of this command.
cable upstream n fragmentation
no cable upstream n fragmentation
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
By default, fragmentation is enabled for all upstream ports on ASIC line cards (Cisco uBR-MC11C, Cisco uBR-MC12C, Cisco uBR-MC14C, Cisco uBR-MC16C, Cisco uBR-MC16S, and Cisco uBR-MC28C) and disabled for all upstream ports on old FPGA line cards.
Note
Command Modes
Interface configuration (cable interface only)
Command History
12.1(4)CX
This command was introduced.
12.2(4)BC1
Support for this command was added to the Release 12.2 BC train.
Usage Guidelines
This command enables and disables DOCSIS layer 2 fragmentation, which reduces run-time jitter experienced by constant bit rate (CBR) slots on the corresponding upstream. Disabling fragmentation increases the run-time jitter, but also reduces the fragmentation reassembly overhead for fragmented MAC frames. For ports running CBR traffic, fragmentation should be enabled (the default).
Note
Examples
The following command shows DOCSIS fragmentation being enabled on upstream 0 on the cable interface in slot 2/0:
Router# configure terminalRouter(config)# interface c2/0Router(config-if)# cable upstream 0 fragmentationRouter(config-if)#Related Commands
cable upstream fragment-force
To specify that a cable interface line card should fragment DOCSIS frames on an upstream when the frame exceeds a particular size, use the cable upstream fragment-force command in cable interface configuration mode. To disable the forcing of fragmentation, use the no form of this command.
cable upstream n fragment-force [fragment-threshold [number-of-fragments] ]
no cable upstream n fragment-force
Syntax Description
Command Default
fragment-threshold is 2000 bytes and number-of-fragments is 3
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
DOCSIS 1.1 allows the CMTS to fragment DOCSIS frames to improve performance, especially in networks that combine real-time traffic, such as voice, with data traffic. The cable upstream fragment-force command allows you to specify the size of frames that should be fragmented, as well as the number of fragments that should be created when fragmenting.
Tip
In the default configuration, the Cisco CMTS fragments DOCSIS frames that are 2,000 bytes or larger in size, and it fragments these frames into three equally-sized fragments. Do not use a fragment size greater than 2,000 bytes on the Cisco uBR-MC5X20S/U cable interface line cards, and do not use a fragment size greater than 3,500 bytes on all other cable interface line cards, unless otherwise instructed by a Cisco TAC engineer.
When using DOCSIS concatenation, you might need to change the cable default-phy-burst command from its default size of 2,000 bytes, so that multiple frames can be concatenated into a maximum-sized burst. If you set the cable default-phy-burst command to zero, the max burst then becomes the lowest of 255 mini-slots, the maximum concatenated burst setting in the DOCSIS configuration file, or the value of the long data grant burst that is specified in the upstream's profile.
Caution
Note
Examples
The following command shows how to enable DOCSIS fragmentation on frames that are 1500 bytes or larger, using four fragments per frame:
Router# configure terminalRouter(config)# interface c2/0Router(config-if)# cable upstream 0 fragment-force 1500 4Router(config-if)#The following example shows how to disable the forced fragmentation of DOCSIS frames on an upstream. This also resets the fragment-threshold parameter to 2,000 bytes.
Router# configure terminalRouter(config)# interface c5/1/0Router(config-if)# no cable upstream 0 fragment-forceRouter(config-if)#Related Commands
cable upstream freq-adj averaging
To specify the percentage of frequency adjustment packets that is required to change the adjustment method from the regular power-adjustment method to the noise power-adjustment method, use the cable upstream freq-adj averaging command in cable interface configuration mode. To disable power adjustments, use the no form of this command.
cable upstream n freq-adj averaging % of frequency adjustment
no cable upstream n freq-adj averaging
Syntax Description
Command Default
No default behavior or values
Command Modes
Interface configuration (cable interface only)
Command History
Examples
The following example shows how to change the power-adjustment method when the frequency-adjustment packet count reaches 50 percent:
Router(config-if)# cable upstream 0 freq-adj averaging 50Related Commands
cable upstream frequency
To enter a fixed frequency of the upstream radio frequency (RF) carrier for an upstream port, use the cable upstream frequency command in cable interface configuration mode. To restore the default value for this command, use the no form of this command.
cable upstream n frequency up-freq-hz
no cable upstream n frequency up-freq-hz
Syntax Description
Command Default
Dynamic (not fixed frequency)
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The upstream channel frequency of your RF output must be set to comply with the expected input frequency of your cable interface line card. To configure an upstream channel frequency, you may:
•
or•
The allowable range for the upstream channel frequency depends on the cable interface line card and Cisco IOS software release being used. See Table 13 for the currently supported values.
Note
Tip
To configure the default upstream frequency (which is no fixed frequency), enter the cable upstream n frequency command without specifying a center frequency.
Examples
The following example shows how to configure the upstream center frequency for port 0, located in slot 6, to 5,700,000 Hz:
Router(config-if)# cable upstream 0 frequency 5700000Router(config-if)# exitRouter(config)# exitRouter# show running-config | include frequencycable upstream 0 frequency 5696000Router#
Note
The following example shows how to configure the upstream center frequency to a frequency (54,700,000 Hz) within the extended Japanese frequency range:
Router# configure terminalRouter(config)# upstream freq-range japaneseRouter(config)# interface cable 3/0Router(config-if)# cable upstream 0 frequency 54000000Router(config-if)# exitRouter(config)# exitRouter#The following example shows how to allow the Cisco CMTS to dynamically specify a center frequency for the upstream port 0:
Router(config-if)# no cable upstream 0 frequencyThe following command example from Cisco IOS Release 12.3 BC illustrates the allowable upstream frequency range in Hz:
Router(config-if)# cable upstream 3 frequency ?<5000000-55000000> Upstream Frequency in HzRelated Commands
cable upstream hopping blind
To override hop decisions, use the cable upstream hopping blind command in cable interface configuration mode. To stop blind hopping, enter the no form of this command.
cable upstream n hopping blind
no cable upstream n hopping blind
Syntax Description
n
Specifies the upstream port for which blind frequency hopping will be activated. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Disabled (hopping is optimized)
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
Enter this command to override the hardware spectrum manager's decision to optimize hopping.
Note
Examples
The following example shows how to specify hopping blind on the upstream port 0:
Router(config-if)# cable upstream 0 hopping blindRelated Commands
cable upstream hop-priority
To configure the priority of the corrective actions to be taken when a frequency hop is necessary due to ingress noise on the upstream, use the appropriate cable upstream hop-priority command in cable interface configuration mode.
cable upstream n hop-priority frequency modulation channel-width
cable upstream n hop-priority modulation frequency channel-width
cable upstream n hop-priority frequency channel-width modulation
Syntax Description
Command Default
The default priority is frequency, modulation, and channel-width.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command specifies the priority of the corrective actions that should be taken when a frequency hop is necessary to correct excessive ingress noise on an upstream. For example, if the upstream on a Cisco uBR-MC16S card is set for the default settings (frequency, modulation, and channel-width), the following occurs when the upstream noise exceeds the CNR threshold value for the current modulation profile:
1.
2.
3.
Allowable DOCSIS channel widths are 3.2 MHz, 1.6 MHz, 800 KHz, 400 KHz, and 200 KHz. If the channel width drops to 200 KHz, but the noise still exceeds the SNR threshold, the CMs go offline.
Note
To use the Dynamic Upstream Modulation feature, you must first create two modulation profiles (using the cable modulation-profile command) and assign them to the upstream (using the cable upstream modulation-profile command).
Examples
The following example shows that when ingress noise on the upstream exceeds the threshold allowed for the primary modulation profile, the Cisco uBR-MC16S line card should first switch to the secondary modulation profile, then try frequency hopping, and if that fails to correct problem, to finally try narrowing the channel width:
Router(config)# interface cable 3/0Router(config-if)# cable upstream 0 hop-priority modulation frequency channel-widthRouter(config-if)# exitRouter(config)#Related Commands
cable upstream ingress-noise-cancellation
To configure how often a cable interface line card should train its noise-cancellation circuitry so as to adjust to noise levels on the upstream, use the cable upstream ingress-noise-cancellation command in cable interface configuration mode. To disable the ingress noise cancellation feature, use the no form of this command.
cable upstream n ingress-noise-cancellation interval
no cable upstream n ingress-noise-cancellation
Syntax Description
Command Default
The default interval is 200 milliseconds.
Command Modes
Interface configuration (config-if)
Command History
Usage Guidelines
Note
Cable interface line cards, such as the Cisco uBR-MC28U/X cards, contain advanced hardware-based noise cancellation circuitry that digitally removes in-channel impairments such as ingress, common path distortion, and certain types of impulse noise. To configure how often these line cards should train their noise cancellation circuity, so as to adapt to changes in the noise types and levels, use the cable upstream ingress-noise-cancellation command.
When you enable ingress noise cancellation on an upstream, the Cisco CMTS periodically schedules a 256-symbol idle slot on the upstream channel. The interval option specified in the cable upstream ingress-noise-cancellation command determines how often this idle slot is generated.
The default for BPE cards is for the card to train its circuitry every 200 milliseconds. The smaller the triggering interval, the faster the card can adjust to changes in ingress noise, which makes the upstream more robust to noise problems, but at the cost of decreasing bandwidth on the upstream channel. To determine the bandwidth cost, in percentage of raw bandwidth, use the following formula:
(256/interval)/channel-symbol-ratewhere interval is the time period in milliseconds specified by the cable upstream ingress-noise-cancellation command, and channel-symbol-rate is the symbol rate in kilohertz. For example, if the upstream is using a 2.56 MHz channel rate and a noise cancellation interval of 10 milliseconds, the bandwidth cost is 1% of the total raw bandwidth:
(256/10)/2560 = 0.01 (1% of bandwidth)Broadband Processing Engine Support
The cable upstream ingress-noise-cancellation command is required on the Cisco uBR10-MC5X20H broadband processing engine (BPE) to enable ingress noise cancellation.
The Cisco uBR10-MCX520S/U BPEs have ingress noise cancellation capability enabled by default, so no configuration of ingress noise cancellation is available in the Cisco IOS software for these cards.
However, for configuration compatibility in support of high availability among Cisco uBR10-MC5X20S/U/H cards, the Cisco IOS software will accept configuration of the cable upstream ingress-noise-cancellation command for these BPEs without generating any warning or error when synchronizing the configuration.
Examples
The following example shows how to configure the first upstream on a Cisco uBR-MC16U/X or Cisco uBR-MC28U/X card to perform ingress noise cancellation every 300 milliseconds:
interface cable 5/0cable upstream 0 ingress-noise-cancellation 300Related Commands
cable upstream load-balance group
To assign an upstream to a load-balance group, use the cable upstream load-balance group command in interface configuration mode. To remove an upstream from a load-balance group, use the no form of this command.
cable upstream uport load-balance group n
no cable upstream uport load-balance group n
Syntax Description
Command Default
An upstream is not assigned to any load-balance groups. If you use the cable load-balance group (interface configuration) command to assign a downstream interface to a load-balance group, all its upstreams are automatically assigned to the same group until you use the cable upstream load-balance group command to reassign an upstream to a different group.
Command Modes
Interface configuration (cable interface only)
Command History
12.2(15)BC1
This command was introduced for the Cisco uBR7246VXR and Cisco uBR10012 routers.
Usage Guidelines
After you have used the cable load-balance group (global configuration) command to initially create and configure a load-balance group, use the cable upstream load-balance group command to assign this load-balance group to an upstream. This enables the cable interface to begin participating in load-balancing operations.
Tip
The following rules apply when creating and assigning load-balance groups:
•
•
•
Examples
The following example shows how to assign the first four upstreams for cable interface 5/1 to load balance group 14:
Router# config terminalRouter(config)# interface cable 5/1/0Router(config-if)# cable upstream 0 load-balance group 14Router(config-if)# cable upstream 1 load-balance group 14Router(config-if)# cable upstream 2 load-balance group 14Router(config-if)# cable upstream 3 load-balance group 14Router(config-if)#Related Commands
cable upstream maintain-psd
To require DOCSIS 2.0 CMs on an A-TDMA-only upstream to maintain a constant power spectral density (PSD) after a modulation rate change, use the cable upstream maintain-psd command in cable interface configuration mode. To return to the default behavior, so that CMs do not need to maintain their power spectral density, use the no form of this command.
cable upstream uport maintain-psd
no cable upstream uport maintain-psd
Syntax Description
uport
Specifies the upstream port to be configured. Upstream port values start with 0 and end with a value that depends on the number of upstream ports on the cable interface line card.
Command Default
Cable modems are not required to maintain their power spectral density after a modulation rate change (no cable upstream maintain-psd)
Note
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
Use this command to specify whether DOCSIS 2.0 CMs should maintain their power spectral density when the Cisco CMTS changes their upstream modulation rate in an upstream channel descriptor (UCD) message. When you configure an upstream with the cable upstream maintain-psd command, the Cisco CMTS sets TLV 15 (Maintain Power Spectral Density) to ON in the UCD messages it sends to the CMs on that upstream.
When TLV 15 is on, and when the new UCD specifies a new upstream modulation rate for the CM, the CM must change its transmit power level to keep its power spectral density as close as possible to what it was before the modulation rate change. The CM must maintain this power spectral density until the CMTS sends a power adjustment command in a Ranging-Response (RNG-RSP) message.
The default configuration (no cable upstream maintain-psd) configures TLV 15 to OFF, and CMs are not required to maintain their power spectral density after a modulation rate change. However, per the DOCSIS specifications, the CMs continue to maintain constant total input power on the upstream.
Note
Examples
The following example shows how to configure four upstreams on a cable interface line card to require cable modems to maintain a constant power spectral density after a modulation rate change.
Router# configure terminalRouter(config)# interface cable c6/1/0Router(config-if)# cable upstream 0 maintain-psdRouter(config-if)# cable upstream 1 maintain-psdRouter(config-if)# cable upstream 2 maintain-psdRouter(config-if)# cable upstream 3 maintain-psdRouter(config-if)# exitRouter(config)# exitRouter#The following example shows how to configure an upstream for the default behavior, which is that CMs are not required to maintain a constant power spectral density after a modulation rate change, but do continue to maintain constant total input power levels on the upstream.
Router# configure terminalRouter(config)# interface cable c5/1/0Router(config-if)# no cable upstream 0 maintain-psdRouter(config-if)# exitRouter(config)# exitRouter#Related Commands
cable upstream docsis-mode
Configures an upstream to use either DOCSIS 1.x or DOCSIS 2.0 modulation profiles.
cable upstream max-ports
To configure the maximum number of upstreams on a downstream (MAC domain) on a Cisco uBR-MC5X20S/U cable interface line card, use the cable upstream max-ports command in cable interface configuration mode. To reset the card to its default value of 4 upstreams per downstream, use the no form of this command.
cable upstream max-ports n
no cable upstream max-ports n
Syntax Description
Command Default
4
Command Modes
Interface configuration (cable interface only)
Command Modes
Usage Guidelines
Use this command to specify how many upstreams a downstream (MAC domain) will support on the Cisco uBR-MC5X20S card, before using the cable upstream connector command to assign upstreams to physical ports on the card. The downstreams on a card can be configured for different maximum upstream values.
After using this command, the valid range for upstreams on that cable interface will be from 0 to one less than the maximum port value. For example, if you use the cable upstream max-ports 6 command to specify a maximum of 6 upstreams for the downstream, the valid range for upstreams will be 0 to 5.
Examples
The following example shows how to configure all of the downstreams on a Cisco uBR-MC5X20S card for a maximum number of 6 upstreams.
Router# configure terminalRouter(config)# interface cable c6/1/0Router(config-if)# cable upstream max-ports 6Router(config-if)# interface cable c6/1/1Router(config-if)# cable upstream max-ports 6Router(config-if)# interface cable c6/1/2Router(config-if)# cable upstream max-ports 6Router(config-if)# interface cable c6/1/3Router(config-if)# cable upstream max-ports 6Router(config-if)# interface cable c6/1/4Router(config-if)# cable upstream max-ports 6Router(config-if)# exitRouter(config)# exitRouter#Related Commands
cable upstream connector
Maps an upstream port to a physical port on the Cisco uBR-MC5X20S cable interface line card for use with a particular downstream.
cable upstream minislot-size
To specify the minislot size (in ticks) for a specific upstream interface, use the cable upstream minislot-size command in cable interface configuration mode. To reset the minislot size to the default for the current channel width setting, use the no form of this command.
cable upstream n minislot-size size
no cable upstream n minislot-size
Syntax Description
Command Default
The default settings vary, depending on the upstream's channel width. The default values were changed in Cisco IOS Release 12.2(15)BC1 and later releases to better optimize data and voice traffic on the upstream. Table 14 lists the default minislot values for each channel width for Cisco IOS releases before and after Cisco IOS Release 12.2(15)BC1.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The minislot size determines the minimum amount of information that can be transmitted on the upstream. How much a particular minislot size can contain depends on the modulation profile and channel width being used, with higher-bandwidth settings allowing larger amounts of data.
Because DOCSIS specifications require that the minislot size contain at least 32 symbols, you might need to change the minislot size whenever you change the channel width or modulation of an upstream, to meet the DOCSIS requirements.
Note
Table 14 lists the default minislot sizes for each channel width for Cisco IOS releases before and after Cisco IOS Release 12.2(15)BC1.
Table 14 Default Minislot Sizes
0.2 MHz
64
0.2 MHz
32
0.4 MHz
32
0.4 MHz
16
0.8 MHz
16
0.8 MHz
8
1.6 MHz
8
1.6 MHz
4
3.2 MHz
4
3.2 MHz
2
6.4 MHz
(DOCSIS 2.0 only)11
1 You must be using a 6.4 MHz channel width if using a minislot size of 1 tick. Otherwise, you will violate the DOCSIS requirements that each minislot should contain 32 symbols.
Increasing the Minislot Size for High Bandwidth Users
The DOCSIS specifications allow a maximum burst limit of 255 minislots, which could require increasing the minislot size from the default values if you are offering service level agreements (SLAs) that offer guaranteed upstream speeds of 2 Mbps or greater, or if you are allowing maximum concatenation bursts greater than 2000 bytes. This is because the default minislot sizes might not accommodate the largest bursts that are possible with these configurations.
The default minislot sizes provide for 8 or 16 bytes per minislot, depending on Cisco IOS release. If the default setting provides 8 bytes per minislot, then the maximum possible burst is 8 bytes * 255 minislots, or 2040 total bytes, which might not be sufficient for certain users with high guaranteed upstream speeds. You should increase the minislot size to accommodate the expected maximum burst transmissions, adding in approximately 10 percent for overhead.
Caution
Examples
The following example shows how to set the minislot size on upstream port 4 to 16:
Router# configure terminalRouter(config)# interface cable 3/0Router(config-if)# cable upstream 4 minislot-size 16Router(config-if)# exitRouter(config)# exitRouter#Related Commands
cable upstream modulation-profile
To assign up to three modulation profiles to an upstream port, use the cable upstream modulation-profile command in cable interface configuration mode. Using the no form of this command will set the upstream modulation profile to the single default profile based on the DOCSIS-mode setting of the upstream.
cable upstream n modulation-profile primary-profile-number [secondary-profile-number] [tertiary-profile-number]
no cable upstream n modulation-profile primary-profile-number [secondary-profile-number] [tertiary-profile-number]
Syntax Description
Command Default
Default modulation profiles are created, using profile numbers 1, 21, 41, 101, 121, 201, 221, and 241, depending on DOCSIS mode and the cable interface line cards being used. See Table 14the description of the cable modulation-profile command for a table of the valid ranges for the individual cable interface cards
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The cable upstream modulation-profile command can assign up to three modulation profiles to an upstream port, depending on the type of cable interface and Cisco IOS software release being used. The third modulation profile is only available for the basic dynamic modulation and is unavailable when a spectrum group is defined for the upstream.
Static Modulation Profile (single profile)
The cable upstream modulation-profile command can assign a single modulation profile to an upstream port on the Cisco uBR7100 series routers and on all cable interface line cards that are available for the Cisco CMTS routers. This modulation profile affects all CMs and set-top boxes that are using that upstream port.
Dynamic Upstream Modulation (up to three profiles)
The cable upstream modulation-profile command can assign up to three modulation profiles to an upstream port to use the Dynamic Upstream Modulation feature. You must assign at least two profiles to activate the Dynamic Upstream Modulation feature. This feature operates differently, depending on the Cisco IOS software release and the cable interface line card that is providing the upstream port:
•
When using the Dynamic Upstream Modulation feature, the primary modulation profile is the default profile. The line card tracks the upstream signal quality by monitoring the signal-to-noise ratio (SNR) value and forward error correction (FEC) counters for the upstream. For a dual modulation profile, the line card tracks the upstream signal quality by monitoring the SNR value, carrier-to-noise ratio (CNR) value, and FEC counters for the upstream.
When the noise on the upstream exceeds the threshold(s) for the primary profile, the upstream switches to the secondary profile in a dual modulation profile. Whereas, in a three modulation profile setup, the upstream can switch from primary profile to the secondary profile or directly to the tertiary profile based on the CNR, SNR, and FEC counter thresholds. Two separate thresholds are used for switching between the primary profile and the secondary profile and from secondary profile to the tertiary profile.
When the noise conditions improve (defined as a SNR value that is 3 dB greater than the threshold value and FEC counters that are below the threshold values), the upstream automatically switches back to the primary modulation profile. For Three Step Dynamic Upstream Modulation, the user can configure the threshold values and FEC counters for the upgrade. However, there is no direct upgrade from tertiary profile to the primary profile. The upgrade follows a sequential order, from tertiary profile to secondary profile and then to the primary profile.
For example, in dual modulation profile, the primary modulation profile could be configured for 16-QAM (or mixed 16-QAM and QPSK) operation, while the secondary profile could be configured for QPSK operation. If noise conditions on the upstream threaten to force CMs offline, the upstream switches to the secondary profile to implement QPSK operation. When the noise ingress conditions are solved, the upstream switches back to 16-QAM operation.
In Three Step Dynamic Upstream Modulation, the primary modulation profile could be configured for 64-QAM operation, while the secondary modulation profile could be configured for 16-QAM operation (or mixed 64-QAM and 16-QAM) and the tertiary modulation profile for QPSK. If noise conditions increase, the upstream switches to the secondary profile to implement 16-QAM (or mixed profile) operation and then to the tertiary modulation profile to implement QPSK operation. When the noise ingress conditions are improved, the upstream switches back to 16-QAM operation (or mixed 64-QAM and 16-QAM), and then to the 64-QAM operation, on further improvement of noise conditions.
Note
When Dynamic Upstream Modulation is enabled and spectrum groups are configured on the same interface, the line cards respond to excessive noise by first switching to the secondary modulation profile. If noise conditions worsen, the line card attempts to find a new upstream channel by changing the modulation or by frequency hopping, and if that fails, the line card reduces the channel width.
Note
•
The Dynamic Upstream Modulation feature on the Cisco uBR-MC16S line card is identical to that for other line cards except that the spectrum management hardware onboard the Cisco uBR-MC16S or Cisco uBR-MC5X20S/U line card uses the CNR value (You can use only the CNR value for a dual profile configuration) in conjunction with the SNR value. The CNR value is a more accurate description of noise conditions on the upstream. Because of this, these line cards switch back to the primary modulation profile when noise conditions improve to a CNR value that is only 3 dB greater than the threshold value (assuming FEC counters are also below the threshold values).
Note
When Dynamic Upstream Modulation is enabled and spectrum groups are configured on the same interface, the line cards respond to excessive noise by taking the first corrective action, as determined by the cable upstream hop-priority command (either frequency hopping or changing to the secondary modulation profile). If noise conditions worsen, the line card takes the second corrective action that has been defined, and if that fails, the line card takes the last corrective action.
Note
For dual profile configuration, we recommend the use of 16-QAM or mixed 16-QAM and QPSK modulation for primary profile and QPSK modulation for the secondary profile. However, this is not mandatory, and the two profiles could be the same (16-QAM or QPSK), but the secondary profile should still be considered a more robust profile than the primary profile in terms of coping with noise conditions.
Tip
Examples
The following example assigns the primary modulation profile 2, the secondary modulation profile 1, and the tertiary modulation profile 4 to upstream port 0 on the cable interface line card in slot 3. This automatically enables the Dynamic Upstream Modulation feature for all CMs using that upstream.
Router(config)# interface cable 3/0Router(config-if)# cable upstream 0 modulation-profile 2 1 4Router(config-if)#The following example assigns the primary modulation profile 2 and the secondary modulation profile 1, to upstream port 0 on the cable interface line card in slot 3. This automatically enables the Dynamic Upstream Modulation feature for all CMs using that upstream.
Router(config)# interface cable 3/0Router(config-if)# cable upstream 0 modulation-profile 2 1Router(config-if)#Related Commands
cable upstream power-adjust
To control power-adjustment methods on the Cisco CMTS, use the cable upstream power-adjust command in cable interface configuration mode. To return to the default values, use the no form of this command.
cable upstream n power-adjust {continue pwr-level | noise perc-pwr-adj | threshold value}
no cable upstream n power-adjust {continue | noise | threshold}
Syntax Description
Command Default
The continue option defaults to 2 dB, the noise option defaults to 30 percent, and the threshold option defaults to 1 dB.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
When a CM comes online, it sets itself for the optimal power level, as determined by the CMTS. As the CMTS periodically polls each CM, the CMTS examines the CM's power level and orders the CM to adjust its power level to adapt to current total attenuation between it and the CMTS. These power adjustments can be required because of temperature variations, upstream frequency hopping, or increased attenuation that has been added either intentionally or unintentionally. The cable upstream power-adjust command controls how the CMTS makes these power adjustments.
Note
Setting the threshold Option
The threshold option specifies the allowable range between the target upstream power for a CM and the actual receive power that the CMTS is measuring for that CM. If the CM receive power level is above or below the target power level by a value that is greater than the threshold option, the CMTS will command the CM to change its power level. When the CMTS receive power level for a CM falls within the threshold range of the target power level, the CMTS stops commanding the CM to change its power level.
For example, the default threshold value of 1 dB means that the CM must be 1 dB above or below its target power range before the CMTS will command it to change its power level. If the CM is within 1 dB of its target power level, the CMTS does not adjust the CM's power level.
Note
Setting the continue Option
The continue option specifies the maximum allowable range for the CM's power level, in relation to its target power level. The CM can operate even at its maximum transmit power level, as long as it is within the continue range. The continue parameter can be set from 2 dB to 15 dB, with a default of 2 dB. For example, with the default value of 2 dB, the CM can operate within 2 dB of its target power level, even if it is transmitting at its maximum power level.
The continue option works together with the threshold option to control the CM's operation. If the CM is within the threshold range, the CMTS sets the Ranging Status field of its RNG-RSP messages to SUCCESS. If the CM is outside the threshold range, but within the continue range, the CMTS sets the Ranging Status field to CONTINUE.
Note
Tip
Note
Determining if the CM has Reached Its Maximum Power Level
Per the DOCSIS specification, the CMTS does not adjust the CM power level by commanding the CM to set itself to an absolute power level. Instead, the CMTS changes the CM power levels by commanding the CM to make relative power adjustments, using increments of +/-0.25 dB (or multiples thereof).
If the CMTS commands a CM to adjust its power level by a particular amount, but the measured power level afterwards shows that the CM has made a smaller adjustment than requested, the show cable flap-list and show cable modem commands show an exclamation point (!) for that particular CM. This typically indicates that the CM has reached its maximum power level.
If the CM has not reached its maximum power level, but the show cable flap-list and show cable modem commands still show an exclamation point (!) for that CM, the problem could be a fault in the upstream path of the cable network. This fault is typically found as amplifier misalignment, where one upstream amplifier is adjusted with too much input attenuation, and the next has too little. The amplifier with too little attenuation enters non-linear operation and begins serious intermodulation.
Another possible cause is a faulty CM or a faulty connection between the CM and cable network. For example, a faulty coaxial cable or bad F-connector could also create noise problems.
Note
Setting the noise Option
The noise option specifies that when the number of power adjustments beyond the threshold amount exceeds a certain percentage of the total Ranging Requests for a CM, the CMTS switches into its noise power-adjustment method. The noise power-adjustment method uses an averaging algorithm to make power adjustments for a particular CM, so that if a modem is experiencing wide swings in its power levels (known as "bouncing'), the CMTS averages the power levels before sending a power adjustment to the CM. The CMTS returns to the normal power adjust method after receiving ten Ranging Request messages with power adjustments below the threshold value.
For example, the cable upstream power-adjust noise 30 command instructs the CMTS that when 30 percent (3 out of the last 10) of the Ranging Responses for a particular CM resulted in a power adjustment beyond the threshold level, the CMTS begins using power averaging for that CM to adjust its power level.
Tip
Note
Examples
The following example shows the commands needed so that the CMTS will begin using the power averaging adjustment method when 50 percent of Ranging Requests result in a power adjustment beyond the threshold level of 2 dB:
Router(config)# interface c6/0Router(config-if)# cable upstream 0 power-adjust threshold 2Router(config-if)# cable upstream 0 power-adjust noise 50Router(config-if)#Related Commands
cable upstream power-level
To set the input power level for the upstream radio frequency (RF) carrier in decibels per millivolt (dBmV), use the cable upstream power-level command in cable interface configuration mode. To restore the default value for this command, use the no form of this command.
cable upstream n power-level dbmv
no cable upstream n power-level dbmv
Syntax Description
Command Default
0 dBmV
Command Modes
Interface configuration (cable interface only)
Command History
11.3 XA
This command was introduced.
12.2(15)BC1
The allowable range of power levels was changed so that it depends on the upstream's channel width.
Usage Guidelines
The Cisco CMTS controls the output power levels of the CMs to meet the desired upstream input power level. The nominal input power level for the upstream RF carrier is specified in decibels per millivolt (dBmV). The default setting of 0 dBmV is the optimal setting for the upstream power level.
The valid range for the input power level depends on the data rate, as expressed as the symbol rate and channel width. Table 15 shows the valid power levels for each allowable rate, as given in the DOCSIS specification. Higher (more positive) values cause the CMs to increase their transmit power, achieving a greater carrier-to-noise ratio (CNR).
Table 15 Allowable DOCSIS Power Levels
160,000
200,000
-16 to +14
320,000
400,000
-13 to +17
640,000
800,000
-10 to +20
1,280,000
1,600,000
-7 to +23
2,560,000
3,200,000
-4 to +26
5,120,0001
6,400,000
-1 to +29 (max. valid value for DOCSIS is +26)
1 The 5.12 MSymbols/sec symbol rate and 6.4 MHz channel width are supported only on upstreams that are configured for DOCSIS 2.0 A-TDMA-only operation.
Note
Tip
Caution
Note
Tip
Examples
The following example shows how to set the input power level for upstream port 0 to -5 dBmV:
Router(config)# interface cable 5/1/0Router(config-if)# cable upstream 0 power-level -5Router(config-if)#Related Commands
cable upstream range-backoff
To specify automatic or configured initial ranging backoff calculation, use the cable upstream range-backoff command in cable interface configuration mode. To set default values, use the no form of this command.
cable upstream n range-backoff {automatic | start end}
no cable upstream n range-backoff
Syntax Description
Command Default
Ranging backoff is enabled with the automatic setting
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The DOCSIS-specified method of contention resolution for CMs used to send data or requests on the upstream channel is a truncated binary exponential back-off with the initial backoff window and the maximum backoff window controlled by the CMTS. The Cisco CMTS router specifies backoff window values for both data and initial ranging and sends these values downstream as part of the Bandwidth Allocation Map (MAP) MAC message. The values are power-of-two values. For example, a value of 4 indicates a window between 0 and 15; a value of 10 indicates a window between 0 and 1023.
The automatic setting is optimized for a maximum of 250 CMs per upstream port. Set manual values for data backoff windows only when operating with more than 250 CMs per upstream port. (The automatic setting is not supported on Cisco uBR-MC5X20S/U cable interface line cards, which should use manually configured ranging backoff instead.)
Tip
Examples
The following example shows how to set the range backoff to automatic for upstream port 2:
Router(config)# interface cable 4/0Router(config-if)# cable upstream 2 range-backoff automaticRouter(config-if)#Related Commands
cable upstream rate-adapt (global)
To globally enable upstream utilization optimization on all cable modem upstream flows, use the cable upstream rate-adapt command in global configuration mode. To disable global upstream utilization optimization, use the no form of this command.
cable upstream rate-adapt [local | priority value | rate number]
no cable upstream rate-adapt [local | priority value | rate number]
Syntax Description
Command Default
Upstream utilization optimization is globally disabled.
Command Modes
Global configuration (config)
Command History
Usage Guidelines
If upstream utilization optimization is globally enabled, activated service flows are configured for upstream utilization optimization. The command also turns on local upstream utilization optimization so specific local upstreams can be configured to be rate-adapt enabled. Using the priority or rate option allows you to restrict upstream utilization optimization to service flows that meet or exceed specified levels for priority or rate.
Examples
The following example enables upstream utilization optimization globally on all upstream flows.
Router(config)# cable upstream rate-adaptRelated Commands
cable upstream rate-adapt (interface)
To enable and configure upstream utilization optimization locally, use the cable upstream rate-adapt command in cable interface configuration mode. To disable upstream utilization optimization on the specified upstream flow, use the no form of this command.
cable upstream port rate-adapt [bcs slots | duration millisecs | fcms-off | priority value |
rate number]no cable upstream port rate-adapt [bcs slots | duration millisecs | fcms-off | priority value |
rate number]Syntax Description
Command Default
Upstream utilization optimization is not enabled on a local upstream.
Command Modes
Interface configuration—cable interface only (config-if)
Command History
Usage Guidelines
If eligible, local upstream flows can utilize upstream utilization optimization.
Examples
The following example enables and configures rate-adapt on upstream 0 with a priority of 6 and a rate of 200.
Router(config-if)# cable upstream 0 rate-adapt priority 6 rate 200Related Commands
cable upstream rate-limit
To set DOCSIS rate limiting for an upstream port on a cable interface line card, use the cable upstream rate-limit command in cable interface configuration mode. To disable DOCSIS rate limiting for the upstream port, use the no form of this command.
cable upstream n rate-limit [token-bucket [shaping]]
no cable upstream n rate-limit
Syntax Description
Command Default
Token-bucket algorithm with traffic shaping
Command Modes
Interface configuration (cable interface only)
Command History
11.3(6)NA
This command was introduced.
11.3(9)NA
The shaping keyword was added.
Usage Guidelines
Upstream rate limiting allows upstream bandwidth requests from rate-exceeding CMs to be buffered without incurring TCP-related timeouts and retransmits. This enables the Cisco CMTS to enforce the peak upstream rate for each CM without degrading overall TCP performance for the subscriber CPE devices. Upstream grant shaping is per cable modem (SID).
When the token-bucket algorithm is configured, the Cisco CMTS automatically drops packets in violation of allowable upstream bandwidth.
Use of the default value (the upstream port's rate limit) enforces strict DOCSIS-compliant rate limiting. Cisco highly recommends to using the default setting of token-bucket with the shaping option.
Examples
The following example shows how to configure the token bucket filter algorithm with traffic shaping on upstream port 4:
Router(config-if)# cable upstream 4 rate-limit token-bucketRelated Commands
cable upstream scheduling type
To enable various scheduler modes, use the cable upstream scheduling type command in interface configuration mode (cable interface only). To disable this feature, use the no form of this command.
cable upstream n scheduling type [ugs | rtps] mode [llq | docsis]
no cable upstream n scheduling type [ugs | rtps] mode [llq | docsis]
Syntax Description
Command Default
The only default is docsis.
Command Modes
Interface configuration —cable interface only (config-if)
Command History
12.3(13(BC)
This command was introduced.
12.2(33)SCA
This command was integrated into Cisco IOS Release 12.2(33)SCA. Support for the Cisco uBR7225VXR router was added.
Usage Guidelines
Any combination of ugs, rtps, llq, and docsis is allowed.
Note the following restrictions:
•
•
Examples
The following example shows how to enable LLQ-type (packet-based) scheduling for UGS services on upstream port 4 on a Cisco CMTS interface:
Router(config-if)# cable upstream 4 scheduling type ugs mode llqThe following example shows how to enable standard DOCSIS (TDM-based) scheduling for rtPS services on upstream port 4 on a Cisco CMTS interface:
Router(config-if)# cable upstream 4 scheduling type rtps mode docsisRelated Commands
show interface cable mac-scheduler
Use this command to confirm whether LLQ scheduling is enabled.
cable upstream scrambler
To enable the cable upstream scrambler, use the cable upstream scrambler command in cable interface configuration mode. To restore the default configuration value for this command, use the no form of this command.
cable upstream n scrambler
no cable upstream n scrambler
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Disabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command causes CMs to enable their pseudo-random scrambler circuitry to improve the robustness of the upstream receiver on the line card.
The scrambler on the upstream radio frequency (RF) carrier enables CMs on the HFC network to use built-in scrambler circuitry for upstream data transmissions. The scrambler circuitry improves reliability of the upstream receiver on the cable interface line card. The upstream scrambler is activated by default and should not be disabled under normal circumstances.
Caution
Examples
The following example shows how to activate the upstream scrambler:
Router(config-if)# cable upstream 0 scrambler#Related Commands
cable upstream shutdown
To disable a single upstream port, use the cable upstream shutdown command in cable interface configuration mode. To enable the upstream port, use the no form of this command.
cable upstream n shutdown
no cable upstream n shutdown
Syntax Description
n
Specifies the upstream port number. Valid values start with 0 for the first upstream port on the cable interface line card.
Command Default
Upstream port enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The cable upstream shutdown command shuts down a single upstream port without affecting any of the other upstream or downstream ports on the cable interface. To shut down the entire interface, use the shutdown command in cable interface configuration mode.
Examples
The following example shows how to disable the upstream port:
Router(config-if)# cable upstream 0 shutdownRelated Commands
cable upstream snr-polling
To configure how often cable interface cards with hardware spectrum management should poll an upstream to determine its Carrier-to-Noise Ration (CNR), use the cable upstream snr-polling command in cable interface configuration mode.
cable upstream n snr-polling interval-in-ms
Note
Syntax Description
Defaults
5000 milliseconds
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The Cisco uBR-MC16S cable interface line cards contain digital signal processors (DSPs) that perform hardware spectrum management. Use the cable upstream snr-polling command to determine how often that hardware should examine an upstream's signal to determine the current CNR value.
Examples
The following example shows how to configure the sixth upstream on a Cisco uBR-MC16S cable interface card so that the DSP samples the upstream signal every 10 seconds (10,000 milliseconds):
Router(config)# interface cable 3/0Router(config-if)# cable upstream 5 snr-polling 10000Router(config-if)#Related Commands
cable upstream spectrum-group
To assign a spectrum group to a single upstream on a cable interface line card, use the cable upstream spectrum-group command in interface configuration mode. To remove a spectrum group from an upstream, use the no form of this command.
cable upstream n spectrum-group group-number
no cable upstream n spectrum-group group-number
Syntax Description
Command Default
No default behavior or values.
Command Modes
Interface configuration
Command History
11.3 NA
This command was introduced.
12.2(15)BC2
The maximum number of spectrum groups was increased from 32 to 40 groups per router.
Usage Guidelines
This command assigns a spectrum group to a single upstream on the cable interface line card. To configure the spectrum groups, use the set of cable spectrum-group commands in global configuration mode.
Note
Examples
The following example shows how to assign spectrum group 12 to the first upstream on the cable interface line card in slot 5/0:
Router(config)# interface cable 5/0Router(config-if)# cable upstream 0 spectrum-group 12Router(config-if)# exitRouter(config)#Related Commands
cable upstream threshold
To configure the upstream for the carrier-to-noise ratio (CNR) and Forward error correction (FEC) threshold values to be used in determining the allowable noise levels, use the cable upstream threshold command in cable interface configuration mode.
cable upstream n threshold cnr-profile1 threshold1-in-dB cnr-profile2 threshold2-in-dB corr-fec fec-corrected uncorr-fec fec-uncorrected
Note
Syntax Description
Defaults
The CNR threshold for the primary modulation profile defaults to 25 dB. The CNR threshold for the secondary modulation profile defaults to 15 dB. The correctable FEC error threshold defaults to 3 percent of total packets received, and the uncorrectable FEC error threshold defaults to 1 percent of total packets received.
Note
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
Separate CNR thresholds are assigned to the primary and secondary modulation profiles. Both profiles, however, are assigned the same correctable and uncorrectable FEC values.
Note
Examples
The following example shows upstream 5 configured with the CNR threshold for the primary modulation profile set to 20 dB, the CNR threshold for the secondary modulation profile set to 10 dB, the correctable FEC error rate set to 5 percent of total packets received on the upstream, and the uncorrectable FEC error rate set to 1 percent of total packets received on the upstream:
Router(config)# interface cable 3/0Router(config-if)# cable upstream 5 threshold cnr-profile1 20 cnr-profile2 10 corr-fec 5 uncorr-fec 1Router(config-if)#Related Commands
cable upstream threshold hysteresis
To configure a hysteresis value to be used in conjunction with the dynamic modulation upgrade thresholds, use the cable upstream threshold hysteresis command in cable interface configuration mode. To use the default hysteresis value, use the no form of this command.
cable upstream n threshold hysteresis hysteresis-in-dB
no cable upstream n threshold hysteresis
Syntax Description
Command Default
The default value of hysteresis is 3 dB.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
The cable upstream threshold hysteresis command can be used to configure a hysteresis value to prevent upstream (US) channels from becoming unstable and continuously changing between modulation profiles.
•
•
Examples
The following example configures a hysteresis value to be used in conjunction with the SNR and CNR thresholds for dynamic modulation upgrade.
Router(config)# interface cable 3/0Router(config-if)# cable upstream 0 threshold hysteresis 5Router(config-if)#Related Commands
cable upstream timing-adjust
To enable upstream timing adjustment for a specified cable interface, use the cable upstream timing-adjust command in cable interface configuration mode. To return to the default values, use the no form of this command.
cable upstream n timing-adjust {continue sec | threshold sec}
no cable upstream n timing-adjust {continue sec | threshold sec}
Syntax Description
Command Default
2 seconds for continue and 1 second for threshold
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
To verify whether or not upstream timing adjustment is configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream timing adjustment is enabled, either or both of the continue and threshold timing adjustment entries are displayed in the show running-config output. If both the continue and threshold upstream timing adjustments are disabled, no timing adjustment entry is displayed in the show running-config output.
If you are having trouble, make sure that the cable connections are not loose or disconnected; the cable interface line card is firmly seated in its chassis slot; the captive installation screws are tight; and you have entered the correct slot and port numbers.
Note
Examples
The following example shows how to set the upstream time adjustment ranging value to 5 seconds:
CMTS01(config-if)# cable upstream 0 time-adjust continue 5The following example shows how to set the threshold value to the default of 12 seconds:
CMTS01(config-if)# cable upstream 0 time-adjust threshold 12cable upstream unfrag-slot-jitter
To control how much jitter can be tolerated on the corresponding upstream due to unfragmentable slots, use the cable upstream unfrag-slot-jitter command in cable interface configuration mode. To disallow all jitter, use the no form of this command.
cable upstream n unfrag-slot-jitter [limit jitter | cac-enforce]
no cable upstream n unfrag-slot-jitter [limit jitter | cac-enforce]
Syntax Description
Command Default
By default, the limit is 0 microseconds and the cac-enforce option is enabled.
Command Modes
Interface configuration (cable interface only)
Command History
12.1(4)CX
This command was introduced.
12.2(4)BC1
Support was added to the Release 12.2 BC train.
Usage Guidelines
This command controls how much jitter due to unfragmented slots is to be tolerated on each port. If the specified value for the tolerated limit is less than the size of a maximum unfragmentable slot, the MAC scheduler automatically blocks the slots in the scheduling table so that the unfragmentable slot can be accommodated in the blocked space and avoid causing excessive jitter to CBR slots.
The cac-enforce option enforces the rule that service flows requesting run-time jitter less than unfragmentable slot jitter should be rejected.
Examples
The following example shows the jitter being set to 10 milliseconds (10,000 microseconds) for upstream port 0 on cable interface 2/0:
Router# configure terminalRouter(config)# interface c2/0Router(config-if)# cable upstream 0 unfrag-slot-jitter limit 10000Router(config-if)#cable vc-map
To map a cable modem to a particular permanent virtual connection (PVC) on an Asynchronous Transfer Mode (ATM) interface, use the cable vc-map command in global configuration mode. To remove this mapping, use the no form of this command.
cable vc-map mac-address atm-interface vpi/vci [cust-name]
no cable vc-map mac-address
no cable vc-map customer cust-name
Syntax Description
Command Default
No default behavior or values
Command Modes
Global configuration
Command History
12.2(11)BC3
This command was introduced for Cisco uBR7100 series and Cisco uBR7246VXR universal broadband routers.
12.2(15)BC2
Support for the customer option was added.
Usage Guidelines
This command maps a cable modem, on the basis of its hardware (MAC) address, to a particular PVC on an ATM interface.
Note
Examples
The following example shows how to enable the use of Layer 2 tunnels and then map specific CMs to specific PVCS:
Router# config terminalRouter(config)# cable l2-vpn-service atm-vcRouter(config)# cable vc-map 0007.0e03.69f9 ATM2/0 1/1Router(config)# cable vc-map 0010.7bed.9c95 ATM2/0 1/2Router(config)# exitRouter#The following example shows the same configuration as above, but with the addition of a customer name that identifies the customer that is using each particular PVC:
Router# config terminalRouter(config)# cable l2-vpn-service atm-vcRouter(config)# cable vc-map 0007.0e03.69f9 ATM2/0 1/1 ENTERPRISE-CO1Router(config)# cable vc-map 0010.7bed.9c95 ATM2/0 1/2 ENTERPRISE-CO2Router(config)# exitRouter#Related Commands
cable wideband auto-reset
To enable wideband auto-reset mode on the CMTS, use the cable wideband auto-reset command in global configuration mode. To disable wideband auto-reset mode, use the no form of this command.
cable wideband auto-reset
no cable wideband auto-reset
Syntax Description
This command has no keywords or arguments.
Command Default
Wideband auto-reset mode is disabled.
Command Modes
Global configuration (config)
Command History
12.3(21)BC
This command was introduced for the uBR10012 router.
12.3(23)BC
This command was updated.
12.2(33)SCA
This command was integrated into Cisco IOS release 12.2(33)SCA.
Usage Guidelines
Use this command to enable wideband auto-reset mode on the CMTS. If wideband auto-reset mode is enabled, wideband cable modems registered on a cable interface as traditional DOCSIS modems (DOCSIS 1.x/2.0 modems) are auto-reset when the cable interface becomes wideband-capable. When a wideband cable modem auto-resets, it deregisters on the CMTS as a traditional DOCSIS cable modem and immediately attempts to re-register as a wideband cable modem.
A cable interface is considered wideband-capable when at least one fully configured and operational wideband channel has been associated with the interface's traditional DOCSIS (narrowband) channel.
For a fully configured wideband CMTS, wideband cable modems may register as traditional DOCSIS modems for a variety of reasons, such as cable interface line card boot order or line card online insertion and removal (OIR). Rather than defer wideband cable modem registration, wideband cable modems are permitted to register as traditional DOCSIS modems.
If a wideband-capable modem registers as a traditional DOCSIS modem, it registers on a primary downstream channel that has been assigned with the downstream cable command to the modem's fiber node if the fiber node is configured. If the modem's fiber node is not configured, the wideband-capable modem can register on any downstream channel that is visible to it (as a traditional cable modem does).
Note
Beginning in Cisco IOS Release12.3(23)BC if the primary downstream channel for this fiber node is assigned from a SPA downstream, then the downstream cable command is not required.When and if a cable interface becomes wideband capable, wideband cable modems that have registered as traditional DOCSIS modems are reset for CMTS routers with wideband auto-reset mode enabled. These modems are only reset when the interface first becomes wideband-capable and are not reset again if they subsequently fail to register as wideband cable modems.
Examples
The following example shows how to enable wideband auto-reset mode:
Router# configure terminalRouter(config)# cable wideband auto-resetRelated Commands
cable bundle
Configures a cable interface to belong to a virtual bundle interface.
downstream cable
Assigns a primary downstream channel for a fiber node.
