Registering DOCSIS 4.0 Modems as DOCSIS 3.1 Modems

Registering DOCSIS 4.0 Modems as DOCSIS 3.1 Modems

Table 1. Feature History

Feature Name

Release Information

Feature Description

Support for 4xOFDM channel bonding on cBR8 platform

Cisco IOS XE Dublin 17.12.1z1

Starting with this release, DOCSIS 4.0 modems on cBR-8 routers may use four OFDM channels for channel bonding, operating at their highest capacity to enhance functionality.

Support for DOCSIS 4.0 Modems registering in D3.1 mode.

Cisco IOS XE Dublin 17.12.1x

In this release, cBR-8 routers now support the registration of DOCSIS 4.0 modems in D3.1 modes. In this mode it is capable of utilizing two OFDM channels, providing enhanced throughput as compared to SCQAM channel.

A D4.0 modem can register in D3.1 or D4.0 DOCSIS mode. It includes the DOCSIS version in the modem advertised D4.0 capability, registered in D3.1 mode on TLV in the Registration Request message that it sends to the CMTS. A CMTS can operate in D3.1 or D4.0 mode in a MAC Domain and advertises the mode in the DOCSIS version TLV in the MDD messages it sends.

Figure 1. Basic Registration and Management Support for DOCSIS 4.0 Modems

At the end of the call-flow shown in the above figure, a D4.0 modem is registered in D4.0 mode on the cBR-8 router and operates in D3.1 mode. The MAC Domain which the modem is registering on is in D3.1 mode, as advertised in the MDD messages for that MAC Domain.

Use the show cable modem docsis version d40-capable [ not-operational | operational ] command to view these modems on cBR-8 routers. Only modems that have registered in D4.0 mode are displayed in this command. This includes modems that are both D4.0 operational or D4.0 registered/D3.1 operational.

  • Modems that are both registered and operational in D4.0 mode are displayed in the operational CLI option of the d40-capable command. In Cisco IOS XE Dublin 17.12.1x, the cBR-8 does not support D4.0 mode in the MAC Domain and so no modems that are D4.0 registered are D4.0 operational. Therefore, the output of the operational CLI option is empty.

  • Modems that are D4.0 registered and D3.1 operational are considered not-operational from the D4.0 standpoint and are displayed as part of the not-operational CLI option for the show cable modem docsis version d40-capable [ not-operational | operational ] command.

Starting with Cisco IOS XE Dublin 17.12.1x,

Starting with Cisco IOS XE Dublin 17.12.1z1,

  • DOCSIS 4.0 modems support a new configuration cable d40-mode in the mac domain. This configuration is not required for 4xOFDM bonding. It enables the advertisement of additional D4.0 specific diplexer TLVs in the MDD.

  • cBR now supports the Data Rate TLV within modem configuration files in 17.12.1z1. This can be used to control service flow traffic rate QoS parameters between 4Gbps and max rate.

  • The following example shows the confiuration for the show cable modem prof-mgmt downstream command:

    Router#show cable modem 206a.9454.30a4 prof-mgmt downstream 
    Downstream Profile Management Data:
    MAC Address            : 206a.9454.30a4
    IP Address             : 9.32.0.43      
    IPv6 Address           : ---                                    
    RxMer Exempt Percent   : 2
    RxMer Margin qDB       : 0
    Automatic Prof Dwngrd  : Active
    Internal PMA           : Active
    Unfit Profile Aging    : Active
    DCID                                   : 159
      Configured Profile(s)                : 0 1 2 
      Profile(s) in REG-RSP-MP             : 0 1 2 
      Profile(s) in DBC-REQ                : N/A
      Current profile                      : 0  [1024-QAM]
      Percentages of ideal BL vs Curr Prof : 99 (better)  0 (equal)
      External Profile Management  (PMA)   : Inactive
      Downgrade profile                    : 0
      Recommend profile                    : 1 
      Unfit profile(s)                     : N/A
      Recommend profile (Expired)          : N/A
      Unfit profile(s)  (Expired)          : N/A
      Flow to Profile override             : Inactive
    Number of SubCarriers  : 4096
    1st Active SubCarrier  : 1126
    # of Active SubCarriers: 1844
    Tx Time                : 0h:30m:22s ago   (Jun 24 11:57:18.000)
    Rx Time                : 0h:30m:22s ago   (Jun 24 11:57:18.000)
    OFDM Profile Failure Rx: 0h:14m:48s ago   (Jun 24 12:12:52.000)
    OFDM Profile Recover Rx: 0h:14m:45s ago   (Jun 24 12:12:55.000)
    MER Poll Period   (min): 60
    Recommend Timeout (min): 120
    Unfit Timeout     (min): 60
    Unfit Profile Hysteresis  (sec): Disabled
    Source             : OPT
    Sub-    RxMER
    SC RxMER Distribution (Excluded SCs counted as 0):
    Each *: 2%
     >44dB: ********* 19.46%
      44dB: ****************** 36.00%
      43dB: **************** 33.78%
      42dB: ****  9.32%
      41dB:   1.30%
      40dB:   0.05%
      39dB: 
      38dB: 
      37dB: 
      36dB: 
      35dB: 
      34dB: 
      33dB: 
     <33dB:   0.05%