Upstream Bonding Support for D-PON on the Cisco CMTS Routers

First Published: November 29, 2010

Cisco IOS Release 12.2(33)SCE provides support for the DOCSIS Passive Optical Network (D-PON). This architecture, also known as RF over glass (RFoG), helps the cable operators to effectively utilize the DOCSIS infrastructure and enter fiber-to-the-home market space.

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Contents

Prerequisites for Upstream Bonding Support for D-PON

The table below shows the hardware compatibility prerequisites for this feature.

Table 1 Upstream Bonding Support for D-PON Hardware Compatibility Matrix

CMTS Platform

Processor Engine

Cable Interface Cards

Cisco uBR10012 universal broadband router

Cisco IOS Release 12.2(33)SCE and later releases

  • PRE4
  • PRE2

Cisco IOS Release 12.2(33)SCH and later releases

  • PRE5

Cisco IOS Release 12.2(33)SCE and later releases

  • Cisco uBR10-MC5X20H
  • Cisco UBR-MC20X20V1
  • Cisco uBR-MC3GX60V2

Cisco uBR7225VXR Universal Broadband Router

Cisco IOS Release 12.2(33)SCE and later releases

  • NPE-G2

Cisco IOS Release 12.2(33)SCE and later releases

  • Cisco uBR-MC88V
1 The Cisco UBR-MC20X20V cable interface line card has three variants—Cisco UBR-MC20X20V-0D, Cisco UBR-MC20X20V-5D, and Cisco UBR-MC20X20V-20D. The Cisco UBR-MC20X20V-0D line card supports 20 upstreams and zero (no) downstreams. The Cisco UBR-MC20X20V-5D line card supports 20 upstreams and 5 downstreams, and the Cisco UBR-MC20X20V-20D line card supports 20 upstreams and 20 downstreams.
2 The Cisco uBR-MC3GX60V line card is not compatible with PRE2.
  • DOCSIS 3.0 cable modems (CMs)
  • DOCSIS 2.0 capable set-top boxes (STBs)
  • You should configure the cable upstream ranging-init-technique 2 command to prevent the use of additional broadcast initial ranging opportunities for the non D-PON reference upstream channels.

Note

The hardware components introduced in a given Cisco IOS Release are supported in all subsequent releases unless otherwise specified.

Restrictions for Upstream Bonding Support for D-PON

  • Multiple CMs cannot work at the same time. Each CM must get a separate time slot for upstream data transmission. Configuring D-PON ensures that the upstream scheduler allows only a single CM to transmit at a particular time.
  • Configuring D-PON in a MAC domain enables D-PON for all MAC domains in the line card. Similarly, disabling D-PON on a MAC domain disables all the MAC domains in the line card.
  • When D-PON is enabled in a MAC domain, you must manually shut down and enable the MAC domain using shutdown and no shutdown command.
  • All frequencies in a MAC domain must have the same configuration for:
    • minislot size
    • channel-width
    • modulation profile
  • Supports only ATDMA DOCSIS mode.
  • The following features are not supported in MAC domains configured for D-PON:
    • Load balancing
    • Spectrum management
    • Upstream configuration (to change upstream configuration, you should shut down the MAC domain)
    • S-CDMA logical channels
    • Lower modulations profiles (D-PON uses only 16 QAM and 64 QAM modulation profiles)
    • Channel-width other than 3.2 MHz and 6.4 MHz
    • In-service Software Upgrade (ISSU)
    • Mixing of D-PON and HFC on the same MAC domain
    • Software licensing

Information About Upstream Bonding Support for D-PON

D-PON is a type of networking that allows the CMTS to transmit RF signals over the optical network. This technology enables the cable operators to use the RF technologies in a Hybrid Fiber-Coaxial (HFC) network.

The downstream data from the CMTS is combined with other RF signals at the hub and is sent to the transmitter. The signal from the transmitter is intended for multiple PONs. Each PON serves 32 homes from a single fiber.

The upstream data from the Optical Network Terminal (ONT) is combined at the splitter and sent to the hub, which is then routed to the optical receiver (RX). Upstream data from multiple optical receivers are combined and sent to the CMTS.

The upstream data to the CMTS contains signals from multiple PONs. Each upstream optical receiver is dedicated to a PON that can have multiple DOCSIS upstream sources (multiple modems and DSG terminals).

A PON can be configured in different ways, depending on the coaxial network. These configurations broadly fall under the following categories:

  • Internal Control Configuration—In this configuration, the internal CM of the ONT controls the laser. Upstream signals go to the Ethernet interface of the CM allowing the ONT to control upstream timing. The device that uses this type of configuration is the Digital Audio Visual Council (DAVIC) set top terminal (STT).

  • External Control Configuration—In this configuration, the presence of the RF at the ONT upstream input activates the laser. The device that uses this type of configuration is the DOCSIS Set-top Gateway (DSG) device.

  • Dual Control Configuration—In this configuration, the home that contains an ONT with and internal CM and other DOCSIS upstream sources, like DSG devices. The RF presence detector or the internal CM control line detects the upstream signal and activates the upstream laser.

D-PON on Upstream Scheduling

In D-PON implementation, the native upstream scheduling software of the CMTS controls the timing of the upstream data transmission. Only one PON Receiver Domain (PRD) is allowed to transmit upstream data at any given point of time, irrespective of the upstream frequency allocation. The reason for this is that two lasers from the ONT of a PRD cannot work simultaneously as it leads to an Optical Beat Interference (OBI). Moreover, the use of a frequency modulation (FM) for and upstream signal transmission results in PHY errors when multiple ONTs within a PON transmits simultaneously.

Initial maintenance regions are scheduled on all upstream channels to prevent the DOCSIS 3.0 CMs in a D-PON environment from failing initial ranging on any upstream channel. When a ranging request is received within a MAC domain configured for D-PON, the CM receives an upstream channel override to the D-PON reference channel (US0).

In this implementation of D-PON, a DOCSIS device within a PRD is given a timeslot to transmit the upstream data, irrespective of the upstream frequency. Therefore, there is no benefit in having more than one upstream in a MAC domain without using the upstream channel bonding feature.

The D-PON feature supports the following service types:

  • Best effort (BE) 3.0 using up to four frequencies concurrently
  • BE 2.0 using only a single frequency
  • Unsolicited grant service (UGS) using only a single frequency
  • Real-time polling service (RTPS) using only a single frequency
  • Non-real-time polling service (nRTPS) using only a single frequency

How to Configure Upstream Bonding Support for D-PON

This section describes how to enable D-PON for a MAC domain on the Cisco CMTS routers:

     Command or ActionPurpose
    Step 1enable


    Example: 
    Router> enable
     

    Enables privileged EXEC mode. Enter your password if prompted.

     
    Step 2configure terminal


    Example: 
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 interface cable {slot/port | slot/subslot/cable-interface-index}


    Example: 
    Router(config)# interface cable 7/0/1
     

    Enters interface configuration mode for the specified cable interface.

    The valid values are:

    • slot—5 to 8
    • port—0 to 4 (depending on the cable interface)
    • subslot—0 or 1
    • cable-interface-index —0 to 14 (depending on the cable interface)
     
    Step 4cable upstream dpon


    Example: 
    Router(config-if)# cable upstream dpon
     

    Enables D-PON for a MAC domain.

     
    Step 5shutdown


    Example: 
    Router(config-if)# shutdown
     

    Shuts down the interface.

     
    Step 6no shutdown


    Example: 
    Router(config-if)# no shutdown
     

    Enables the interface.

     
    Step 7end


    Example: 
    Router(config-if)# end
     

    Exits interface configuration mode and returns to the privileged EXEC mode.

     

    DOCSIS 3.0 Cable Modems Upstream Bonding Enters Partial Bonding

    Sometimes, upstream bonding enters partial bonding while reverting to the original CLC after switchover.
    In the following example, the switchover is performed between CLC in slot 1 and 0. After reverting to CLC in slot 1, C1/0/3/UB turns to C1/0/3/p. The following output highlights the change:
    Router# show cable modem
Load for five secs: 1%/0%; one minute: 2%; five minutes: 2% Time source is NTP, 13:00:25.570 UTC Thu Feb 18 2016
                                                                                       D
MAC Address    IP Address      I/F           MAC               Prim  RxPwr  Timing Num I
                                             State             Sid   (dBmv) Offset CPE P
4844.8789.e0fc 10.78.100.6     C1/0/0/UB     w-online          6     -0.50  1787   0   N
c8fb.2639.33d0 10.78.100.7     C1/0/1/UB     w-online          1     -1.00  1793   0   N
4844.8789.e10e 10.78.100.10    C1/0/2/UB     w-online          1     -0.50  1784   0   N
602a.d0a2.9b3e 10.78.100.11  C1/0/3/p   w-online          4     1.50   1789   0   N
0025.2ecf.f922 10.78.100.8     C1/0/4/UB     w-online          1     -1.00  1788   0   N
    This partial bonding can be recovered using the shutdown and no shutdown commands on the related upstream port under the controller. The following is a sample configuration: 
    Router(config)# controller Upstream-Cable 1/0/3 
Router(config-controller)# us-channel 0 shutdown 
Router(config-controller)# no us-channel 0 shutdown

    Verifying the Upstream Bonding Support for D-PON

    To verify the upstream scheduler output for a MAC domain configured with D-PON, use the show interface cable mac-scheduler command.


    Note
    The D-PON reference channel US0 (US channel-id 1) MAP serves as a template for producing other MAPs within the MAC domain. Therefore, some of the statistics related to upstream scheduling is not relevant for other channels, except for the D-PON reference channel. 
    Router# show interface cable 7/0/2 mac-scheduler 0
     DOCSIS 1.1 MAC scheduler for Cable7/0/2/U0: rate 15360000
     wfq:None
     Req Slots 124, Req/Data Slots 13
     Init Mtn Slots 2243, Stn Mtn Slots 5
     Short Grant Slots 0, Long Grant Slots 0
     Adv Phy Short Grant Slots 1, Adv Phy Long Grant Slots 0
     Adv Phy UGS Grant Slots 0
     Awacs Slots 0
     Fragmentation count 0
     Fragmentation test disabled
     Avg upstream channel utilization : 0%
     Avg percent contention slots : 97%
     Avg percent initial ranging slots : 3%
     Avg percent minislots lost on late MAPs : 0%
     Sched Table Rsv-state: Grants 0, Reqpolls 0
     Sched Table Adm-State: Grants 0, Reqpolls 0, Util 0%
     UGS    : 0 SIDs, Reservation-level in bps 0
     UGS-AD : 0 SIDs, Reservation-level in bps 0
     RTPS   : 0 SIDs, Reservation-level in bps 0
     NRTPS  : 0 SIDs, Reservation-level in bps 0
     BE     : 0 SIDs, Reservation-level in bps 0
     MAP TSS: lch_state 13, init_retries 0
              late_initial_maps 0, late_ucd_maps 0
              mac-phy tss errors 0
! Only the D-PON reference channel will display the following
     Queue[Rng Polls] 0/128, 0 drops, flows 0 max 3
     Queue[CIR Grants] 0/256, 0 drops, flows 0 max 1
     Queue[BE(7) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(6) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(5) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(4) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(3) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(2) Grants] 0/64, 0 drops, flows 0 max 2
     Queue[BE(1) Grants] 0/64, 0 drops, flows 0 max 0
     Queue[BE(0) Grants] 0/64, 0 drops, flows 0 max 1
     BG pending grant list entries: 0
     BG delay list entries: 0

    Router# sh interfaces cable 1/0/0 mac-scheduler 0

     DOCSIS 1.1 MAC scheduler for Cable1/0/0/U0 : rate 15360000
     wfq:None
     us_balance:OFF
     dpon_mode:OFF
     fairness:OFF
     Queue[Rng Polls] flows 0
     Queue[CIR Grants] flows 0
     Queue[BE(07) Grants] flows 0
     Queue[BE(06) Grants] flows 0
     Queue[BE(05) Grants] flows 0
     Queue[BE(04) Grants] flows 0
     Queue[BE(03) Grants] flows 0
     Queue[BE(02) Grants] flows 0
     Queue[BE(01) Grants] flows 0
     Queue[BE(00) Grants] flows 0
     Req Slots 3075489702, Req/Data Slots 277062737
     Init Mtn Slots 1236108257, Stn Mtn Slots 4010630
     Short Grant Slots 0, Long Grant Slots 0
     Adv Phy Short Grant Slots 0, Adv Phy Long Grant Slots 0
     Adv Phy UGS Grant Slots 0
     Avg upstream channel utilization : 0%
     Avg percent contention slots : 97%
     Avg percent initial ranging slots : 1%
     Avg percent minislots lost on late MAPs : 0%

     MAP TSS: lch_state 10, init_retries 0
              late_initial_maps 0, late_ucd_maps 0
              mac-phy tss errors 0, missed ccc 0

    Additional References

    The following sections provide references related to the Upstream Bonding Support for D-PON feature.

    Related Documents

    Related Topic

    Document Title

    CMTS commands

    Cisco IOS CMTS Cable Command Reference

    Prisma D-PON

    Cisco Prisma D-PON

    Standards

    Standards

    Title

    SCTE IPS SP 910

    IPS SP 910 RFoG System

    http:/​/​www.ieee802.org/​3/​minutes/​nov08/​1108_​SCTE_​IPS_​WG5_​to_​802_​3.pdf

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    Feature Information for Upstream Bonding Support for D-PON on the Cisco CMTS Routers

    Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http:/​/​www.cisco.com/​go/​cfn. An account on Cisco.com is not required.


    Note

    The table below lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

    Table 2 Feature Information for Upstream Bonding Support for D-PON on the Cisco CMTS Routers

    Feature Name

    Releases

    Feature Information

    Upstream Bonding Support for D-PON

    12.2(33)SCE

    This feature was introduced for the Cisco uBR10012 and Cisco uBR7200 series Universal Broadband Routers.

    The following commands are new or modified:

    • cable upstream dpon
    • show interface cable mac-scheduler