Overview for Cisco DOCSIS 3.0 Downstream Solution
NoteThe information provided in this document for Cisco DOCSIS 3.0 Downstream Solution is specific to Cisco IOS Releases 12.3(23)BC and 12.2(33)SCB (and later releases). For information that is specific to Cisco IOS Releases 12.3(21)BC and12.3(21a)BC3, see theCisco Cable Wideband Solution Design and Implementation Guide for these releases at http://www.cisco.com/en/US/docs/cable/cmts/wideband/solution/guide/release_1.0/wb_solu.html
This chapter provides an overview of the Cisco DOCSIS 3.0 Downstream Solution, and contains the following major topics:
To meet the increasing demand for downstream (DS) and upstream (US) bandwidth, Cisco offers low, mid, and high-range platforms with a rich set of DOCSIS 3.0 compliant line cards. This document describes in detail how multiple RF channels can be aggregated in the downstream direction to achieve significant data rate improvements over single channel modems. For example, in the downstream direction an 8-channel modem can download data at up to 300 Mbps at an Annex B cable plant.
The Cisco CMTS platform supports DOCSIS 3.0 cable interface line cards that can be grouped into the following two main categories:
- Integrated-cable RF-based line cards—This includes the Cisco uBR-MC8X8V and Cisco UBR-MC20X20V cable interface line cards.
- Modular-cable line cards —This includes the SPA-24XDS-SFP Wideband Docsis SPA and the Cisco uBR-MC3GX60V cable interface line card. This line card category requires the use of an EQAM device on the downstream portion of the network.
Depending on the cable plant requirement, choose any of the available Cisco platforms and cable interface line cards:
- Low-range requirement—The Cisco uBR7225 router platform, which can support up to two Cisco uBR-MC8X8V integrated cable interface line cards.
- Mid-range requirement—The Cisco uBR7246 router platform, which can support up to four Cisco uBR-MC8x8V integrated cable interface line cards.
- High-range requirement—The Cisco uBR10012 router platform, which offers maximum flexibility by supporting the Cisco UBR-MC20X20V integrated cable line card, the Modena SIP-based modular cable SPA, and the Cisco uBR-MC3GX60V modular cable line card.
NoteCisco uBR-MC8X8V, Cisco UBR-MC20X20V, and Cisco uBR-MC3GX60V cable interface line cards natively support upstream channel bonding in hardware. The Cisco Wideband SIP/SPA combined with a Cisco uBR-MC5X20H line card can also be used to deploy upstream channel bonding in software.
Cisco DOCSIS 3.0 M-CMTS Solution
The Cisco DOCSIS 3.0 modular cable termination system (M-CMTS) solution aggregates multiple downstreams into a single logical wideband channel to deliver a higher bandwidth to the wideband cable modem, which was not possible with the DOCSIS 2.0 solution.
In the Cisco M-CMTS implementation, the DS channels are encapsulated for the Gigabit Ethernet using the Downstream External PHY Interface (DEPI) protocol as defined by DOCSIS 3.0 M-CMTS. The DS channels can be used either as primary-capable channels (narrowband channels), or as part of bonded channels (wideband channels), or both. For more information about the Cisco DOCSIS 3.0 Downstream Solution for the M-CMTS, see Cisco DOCSIS 3.0 Downstream Solution Overview for the Cisco M-CMTS.
Cisco DOCSIS 3.0 I-CMTS Solution
The Cisco DOCSIS 3.0 integrated cable modem termination system (I-CMTS) solution enables high-bandwidth access networks. In the Cisco I-CMTS implementation, the DS channels are processed and encapsulated by the downstream channels of the line cards, which can be used either as primary-capable channels (narrowband channels), or as part of bonded channels (wideband channels), or both. For more information about the Cisco DOCSIS 3.0 Downstream Solution for I-CMTS, see Cisco DOCSIS 3.0 Downstream Solution Overview for the I-CMTS.