Upstream Bonding Support for D-PON

The DOCSIS Passive Optical Network (D-PON) architecture, also known as RF over Glass (RFoG), helps the cable operators enter fiber-to-home market space and utilize the DOCSIS infrastructure effectively.

Hardware Compatibility Matrix for the Cisco cBR Series Routers


Note
The hardware components that are introduced in a given Cisco IOS-XE Release are supported in all subsequent releases unless otherwise specified.
Table 1. Hardware Compatibility Matrix for the Cisco cBR Series Routers

Cisco CMTS Platform

Processor Engine

Interface Cards

Cisco cBR-8 Converged Broadband Router

Cisco IOS-XE Release 16.5.1 and Later Releases

Cisco cBR-8 Supervisor:

  • PID—CBR-SUP-250G

  • PID—CBR-CCAP-SUP-160G

Cisco IOS-XE Release 16.5.1 and Later Releases

Cisco cBR-8 CCAP Line Cards:

  • PID—CBR-LC-8D30-16U30

  • PID—CBR-LC-8D31-16U30

  • PID—CBR-RF-PIC

  • PID—CBR-RF-PROT-PIC

  • PID—CBR-CCAP-LC-40G

  • PID—CBR-CCAP-LC-40G-R

  • PID—CBR-CCAP-LC-G2-R

  • PID—CBR-SUP-8X10G-PIC

  • PID—CBR-2X100G-PIC

Digital PICs:

  • PID—CBR-DPIC-8X10G

  • PID—CBR-DPIC-2X100G

Cisco cBR-8 Downstream PHY Module:

  • PID—CBR-D31-DS-MOD

Cisco cBR-8 Upstream PHY Modules:

  • PID—CBR-D31-US-MOD

Note

Do not use DPICs (8X10G and 2x100G) to forward IP traffic, as it may cause buffer exhaustion, leading to line card reload.

The only allowed traffic on a DPIC interface is DEPI, UEPI, and GCP traffic from the Cisco cBR-8 router to Remote PHY devices. Other traffic such as DHCP, SSH, and UTSC should flow via another router, since DPICs cannot be used for normal routing.

Prerequisites for Upstream Bonding Support for D-PON

  • 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.

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.

  • Cisco cBR-8 does not support Upstream Bonding for D-PON on Remote-PHY.

  • It is possible to enable or disable D-PON for individual Mac domain.

  • When you enable D-PON on a MAC domain, you must manually shut down and enable the MAC domain using shutdown and no shutdown command.

  • When enabling D-PON on a MAC domain, the D-PON is not supported with upstream balance-scheduling. Remove the upstream balance scheduling using the following command: 
    no cable upstream balance-scheduling

  • 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 cBR router. The bonding group must include a reference channel which is default to the upstream channel 0.


Note

The USCB can support a maximum of 4 US channels in a RFOG MAC domain in the following combination:

  • US0

  • US0, US1

  • US0, US1, US2

  • US0, US1, US2, US3

All US channels must be configured to have the same number of minislots, channel width (only 3.2 and 6.4 MHz supported), DOCSIS mode (only ATDMA supported) and modulation profile.

When enabling DPON on a MAC Domain, remove the command "cable upstream balance-scheduling? as DPON is not supported with upstream balance-scheduling.

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface cable slot/subslot/cable-interface-index

Example:

Router(config)# interface cable 8/0/0

Enters interface configuration mode for the specified cable interface.

Step 4

cable upstream dpon

Example:

Router(config-if)# cable upstream dpon

Enables D-PON for a MAC domain.

Step 5

shutdown

Example:

Router(config-if)# shutdown

Shuts down the interface.

Step 6

no shutdown

Example:

Router(config-if)# no shutdown

Enables the interface.

Step 7

end

Example:

Router(config-if)# end

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

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 8/0/0 mac-scheduler 1
     DOCSIS 1.1 MAC scheduler for Cable8/0/0/U1 : rate 30720000
     wfq:None
     us_balance:OFF
     dpon_mode:ON
     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 1824595508, Req/Data Slots 10640906
     Init Mtn Slots 89924653, Stn Mtn Slots 989543
     Short Grant Slots 0, Long Grant Slots 0
     Adv Phy Short Grant Slots 538, Adv Phy Long Grant Slots 219831
     Adv Phy UGS Grant Slots 0
     Avg upstream channel utilization : 0%
     Avg percent contention slots : 98%
     Avg percent initial ranging slots : 1%
     Avg percent minislots lost on late MAPs : 0%
     MAP TSS: lch_state 9, 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

Prisma D-PON

Cisco Prisma D-PON

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Feature Information for Upstream Bonding Support for D-PON

Use Cisco Feature Navigator to find information about the 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 the https://cfnng.cisco.com/ link. An account on the Cisco.com page is not required.


Note

The following table lists the software release in which a given feature is introduced. 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

Feature Name

Releases

Feature Information

Upstream Bonding Support for D-PON

Cisco IOS XE Fuji 16.7.1

This feature was integrated on the Cisco cBR Series Converged Broadband Routers.