Post on 15-Jan-2016
transcript
DOCSIS®
Rev. A00
Items for discussion
Agenda
DOCISISDOCSIS 3.0
DOCSIS/EuroDOCSIS Overview of Standards, Features &
Benefits
DOCSIS 3.0/EuroDOCSIS 3.0 CATV Market Dynamics New Technical Directions & Features Network Preparation
DOCSIS® 2Confidential & Proprietary Information of VeEX Inc
DOCSIS Review
3Confidential & Proprietary Information of VeEX Inc
Overview, Features & Benefits
DOCSIS system Enables transparent bi-directional of Internet Protocol (IP) traffic, between the cable system headend and
customer location
DOCSIS specification Defines PHY & MAC layer protocols for communication & Ethernet frame transport between CMTS & CM
DOCSIS network comprises: Cable Modem Termination System (CMTS) located at the headend
Cable Network - an all-coaxial or hybrid-fiber/coax (HFC) cable network
Cable Modem (CM) located at the Customer Premise
An Overview
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Transparent IP traffic
Wide Area Network
Cable Network (HFC)
CMTS Cable Modem CPE
CM/CPE Interface
CMTS/WAN Interface
Milestones
DOCSIS
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HFC Spectrum Allocation
DOCSIS
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The frequency spectrum used in an HFC network is split into two parts: Downstream spectrum which delivers services from the headend to the end user Upstream spectrum for sending traffic from the end user to the operator
EuroDOCSISUS
Analog VideoPAL
Digital VideoMPEG/DVB + VOD
EuroDOCSISDS
5MHz 65 87 108 862MHz
FM
Upstream Downstream
80
Europe
US DOCSISUS
Analog VideoNTSC
Digital VideoMPEG/DVB + VOD
US DOCSISDS
5MHz 42 87 108 862MHz
FM
Upstream Downstream
80
North America
The DOCSIS Specification defines Modulation and Coding Schemes outlined in the following table for the Upstream
Upstream Physical Layer
DOCSIS
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The DOCSIS Specification defines Modulation and Coding Schemes outlined in the following table for the Downstream
Downstream Physical Layer
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Ranging is used to synchronize CMs and align them with the CMTS TDMA requires coarse alignment (±800 nsec) S-CDMA requires accurate alignment (±1 nsec) CM sends a RNG-REQ message CMTS responds with a RNG-RSP message
Contains Timing Adjust (Resolution = 0.3815 nsec) also Power adjust, Frequency adjust, Pre-EQ parameters
Ranging is a two-step process: Initial maintenance (coarse time alignment) Periodic station maintenance (fine time alignment)
Power Ranging
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DOCSIS MAC Forms part of the data link layer that supports topology dependent functions Uses services of the Physical Layer to provide services to the Logical Link Control (LLC) In the OSI 7-layer model, the Media Access Control is a part of layer 2, the data link layer.
CM Protocol Stack
DOCSIS
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Media Access Control (MAC) Sub-Layer Controls access to the Physical Layer (the channel) Allows multiple users to share a communications channel Separate physical channels (upstream/downstream) controlled by the CMTS No direct peer-to-peer (CM-to-CM) communication
Downstream MAC Only one transmitter (CMTS) and multiple receivers (CMs) Quality of Service (QoS) can be assured by:
Token bucket rate limiting, Reserved data rates, Traffic Priority
Upstream MAC Multiple transmitters (CM) with One receiver (CMTS) The CMTS arbitrates access to the channel Each upstream channel is described in mini-slots MAP messages are broadcast downstream to describe which CM can transmit and when Access Control is Reservation based
Media Access Control (MAC)
DOCSIS
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DHCP Server Assigns IP addresses to client computers Addresses are “leased” to clients (Cable Modems or CPEs) for a period of time IP addresses can be reserved for specific clients or assigned from “pools” Clients may be authenticated based on their MAC address Address may be assigned from different “pools” based on extended options
DHCP Process The DHCP server requests the following parameters from the Cable Modem (CM): IP address of the CM IP address of the TFTP Server (for DOCSIS Configuration file) IP address of the DHCP Relay Agent (if DCHP server resides on a different network) TFTP/DOCSIS Configuration file name Subnet Mask to be used by the CM Default IP Gateway Time of Day Server and SYSLOG Server IP address
DHCP Server & Process
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Time of Day (ToD) Server Internet Time Protocol (ITP) per RFC 868 UDP and TCP requests honored on port 37 32-bit value defining the number of seconds since 00:00 (midnight January 1, 1900 GMT)
Time of Day (TOD) Server
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TFTP Server
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TFTP (Trivial File Transfer Protocol) Server In accordance with RFC 1350 UDP port 69 Small and easy to implement with read and write to and from remote servers
The following settings are mandatory in the TFTP configuration file: Network Access Configuration Setting Class of Service Configuration Setting
The following settings are optional: Downstream Frequency Upstream Channel ID Vendor ID Baseline Privacy SNMP Write-Access Control, SNMP MIB Object & SNMP IP Address (if applicable) Software Server IP Address CPE Ethernet MAC Address Vendor-Specific Configuration (if applicable)
DOCSIS 3.0
CATV Market Dynamics
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Support new high bandwidth services of 50 to 100Mbps
Migrate existing customers to higher tier services
Better and more robust data encryption
Provide more IP address space using IPv6
Limit and reduce node splits
Reduce overall cost of CMTS ports Independent scalability of upstream & downstream
Business Drivers
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Higher Bandwidth Applications
DOCSIS 3.0
Digital Photos
Gaming
MP3 WMV
DVD Blu-ray
SDTV HDTV Mobile
Video
iPod Walkman
You Tube
VODDVR/PVR
Data & VoIP
Home Networks
Web 2.0
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Consumers greed for speed
DOCSIS 3.0
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High bandwidth residential data and content Video and photo uploads
Proliferation of social networking sites and applications
IP Video over DOCSIS (VDOC) High definition Video to multiple devices PCs, hybrid STBs, portable devices High bandwidth Internet streaming
High Bandwidth Video conferencing Cisco TelePresence
Commercial service High bandwidth symmetrical data services Bonded E1/T1 circuit emulation High bandwidth Ethernet / L2VPN services
Services driving Channel Bonding
DOCSIS 3.0
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DOCSIS 3.0
New Technical Directions & Features
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Major Feature Overview
DOCSIS 3.0
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Channel bonding basically means data is transmitted to/from Cable Modems using multiple individual RF channels instead of a single channel
Channel Bonding
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Using DOCSIS 3.0, data is transmitted to cable modems using multiple channels
Throughput Compared
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DOCSIS VersionDate Rates – Annex A
Downstream Upstream
1.1 ~ 55.62 (50) Mbps 10.29 (9) Mbps
2.0 ~ 55.62 (50) Mbps 30.72 (27) Mbps
3.0 (4 Channels) ~ 222.48 (200+) Mbps 122.88 (108+) Mbps
3.0 (8 Channels) ~ 444.96 (400+) Mbps 122.88 (108+) Mbps
Advanced Time Division Multiple Access (A-TDMA) Used widely in DOCSIS 2.0 and DOCSIS 1.1 systems
CMs transmit one at a time, occupying the entire upstream channel during transmission
Transmissions consist of a preamble, data burst, and guard time
Better immunity to narrowband interferers and generally performs better above 15 MHz
Synchronous Code Division Multiple Access (S-CDMA) Applicable to DOCSIS 2.0/3.0 systems only
Multiple CMs able to transmit simultaneously with shorter preamble and no guard times
Better immunity to burst noise and performance below 15 MHz
Upstream PHY Modes
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5MHz 42MHz or 65MHz
Cable Modem Termination System (CMTS) A downstream packet stream or flow is distributed to a set of
channels called the Downstream Bonding Group (DBG) Bonded packets are marked with a sequence # A Downstream Service ID (DSID) identifies a stream of packets
Cable Modem (CM) Bonded packets can arrive out of order Bonded packets are “re-sequenced” using the sequence # The DSID is used re-sequence each flow or group of flows
independently
Downstream Channel Bonding
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Upstream Bonding Packet Striping of a minimum of 4 channels
Delivers in excess of 50 Mbps Single flow can consume entire bandwidth on multiple Upstream Channels Implements Continuous Concatenation & Fragmentation (CCF)
Improved form of concatenation and fragmentation needed for DOCSIS 3.0 operation
Upstream Channel Bonding
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P1P3 P2P4
US1
US2
U3
Request 1000 bytes
Grant 200
Grant 300 bytes
Grant 500 bytes
CMTS
Cable Modem
Cable Modem (CM) When a CM is ready to transmit data, it randomly selects a Request contention interval
among all upstream channels Transmits a 7-byte REQ message to the CMTS, which identifies the CM (from the
Service ID) and specifies the number of bytes in queue Retransmits the request, if there is no response from the CMTS
Cable Modem Termination System (CMTS) Queues and prioritizes the incoming REQs Selects an upstream channel and reserves future mini-slots for the requesting CMs An individual request can be split into multiple “grants” on different channels Communicates the grants to the CMs via MAP messages
Upstream Requests and Grants
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MAC Domain Defined as a sub-component of the CMTS Controls all DOCSIS functions on a set of downstream and upstream channels Contains at least one DS channel and one US channel Provides layer 2 data forwarding services between the CMTS and all the CMs registered
to that particular MAC domain Implements all DOCSIS MAC management message exchanges with CMs across multiple
US & DS channels using a common MAC address Implements load balancing of CMs and bandwidth of channels
MAC Domain
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MDD Descriptor Describes Plant topology
Plant Topology Describes fiber nodes and how they
are split/combined
Ambiguity Resolution Downstream Bonding Group (DBG)
Upstream/Downstream bonding Sequencing for packet flows Dynamic Bonding Change (DBC) Bonding group attributes (low latency)
CM status report Reports CM condition
New MAC Functions
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CM Control report Used to force actions such as reboot,
or channel muting.
Message Description
MDD MAC Domain Descriptor
B-INIT-RNG-REQ Bonded Initial Ranging Request
DBC-REQ Dynamic Bonding Change Request
DBC-RSP Dynamic Bonding Change Response
DBC-ACK Dynamic Bonding Change Acknowledge
DPV-REQ DOCSIS Path Verification Request
DPV-RSP DOCSIS Path Verification Response
CM-STATUS Cable Modem Status Report
CM-CTRL Cable Modem Control
REG-REQ-MP Multipart Registration Request
New MAC Management Messages (partial list)
DOCSIS 3.0
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During initialization, the CM downloads a configuration file from the cable operator
The Config file defines: Quality of Service (QoS) parameters
Priority, rate limiting, bandwidth guarantees, etc. Filters
block Windows file sharing (netBIOS, SMB, CIFS) Privacy (encryption) parameters
The CM then sends a Registration Request message to the CMTS containing the QoS parameters
CM Provisioning
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Authentication & Key Exchange
Cable Modem Registration
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Scan digital channels & acquire QAM/FEC/MPEG lock of DOCSIS DS & DOCSIS PID
SYNC, UCD, MAP messages
Select upstream channel listed in MDD
MDD message
Tune additional downstream frequencies to determine service group
B-INIT-RNG-REQ message
DHCP DISCOVER packet
REG-REQ message
DHCP RESPONSE packet
DHCP REQUEST packet
DHCP OFFER packet
Transition to ranging station maintenance
REG-ACK message
REG-RSP message
BPI+ initialization if configured
TOD Request/Response messages
TFTP Request/Response messages
Provides Rx-Chan(s)
Receive Rx-Chan(s) configuration
Confirm all Rx Channels
Cable Modem
Receive MAC Domain Descriptor (MDD) Message
Find Initial Maintenance interval in MAP messagesSend RNG-REQ, receive RNG-RSP, adjust Txmitter
CMTS
Establish IPv4 or IPv6 communication via DHCP
Download Configuration File (TFTP)
Send REG-REQ, receive REG-RSP, send REG-ACK
Secure provisioning prevents unauthorized CMs from accessing the network
Early Authentication and Encryption (EAE) Provides enhanced security Authenticates CM after power ranging and before DHCP process Signaling occurs in the MDD message (TLV 6) Enabled on either a per CM or per MAC domain basis
CMTS Proxy Server CMTS acts as a TFTP server to the CM and as a TFTP client to the provisioning server Config parameters are enforced since CMTS receives the file first Provides config file authorization
DHCPv6 authentication New MIC hash algorithm (MMH)
Better Network Security
DOCSIS 3.0
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IPv6 in Cable Networks
DOCSIS 3.0
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IPv6 is fundamental feature of DOCSIS 3.0 and provides numerous benefits: New address size and format - 128 bit vs 32 bit addressing Smarter packet – simplified provisioning, built-in security, improved mobility, etc. Restores global connectivity – removes Network Address Translation (NAT) CM operates in bridging or routing modes CM management stack operation - IPv4 only, IPv6 only or Dual mode MDD message contains IP type - conveyed between the CMTS and CM
DOCSIS 3.0 review Physically the same as DOCSIS 2.0 signals Consists of multiple QAM signals bonded logically together Bonded channels can be contiguous or non-contiguous:
Contiguous - consists of frequency consecutive signals Non-contiguous – interspersed with other carriers
MPEG-2 transport for downstream signals QAM transport for upstream signals IPv4 or IPv6 support Enhanced security using EAE, etc.
Quick Summary
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Network Preparation
DOCSIS 3.0
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Basic steps for being prepared
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Where can more RF bandwidth come from?
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Reclaim Analog bandwidth for more digital spectrum More QAM channels for Digital Broadcast, VoD, SDV and DOCSIS
Node splits Reduce the homes passed per HFC node, reducing contention/home for Unicast services
Switched Digital Video (SDV) Transmit only the content being actively watched
Efficient channel use Manage channel lineup, fill the gaps, and mitigate noise to utilize available spectrum
1GHz upgrade Make new spectrum for new CPE above 860 MHz
Bandwidth Management
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Today 870MHz
Soon 1GHz
How much can we gain with spectrum changes?
DOCSIS 3.0
250 Mbps
500 Mbps
1000 Mbps
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Information Sources
Acknowledgements
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Common terms in DOCSIS systems
Acronyms/Abbreviations
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Thank you.Any questions?