Table Of Contents
DOCSIS 1.1 for Cisco uBR7200 Series
Universal Broadband RoutersDOCSIS 1.1 Features in Cisco IOS Release 12.1 CX
Service Template/Class Manager
Payload Header Suppression and Restoration
Baseline Privacy Interface Plus
Additional DOCSIS 1.1 Features in Cisco IOS Release 12.1(7)CX1
Migrating from Earlier Versions of DOCSIS
Baseline Privacy Interface Plus Enhancement
Baseline Privacy Interface Plus
Supported Standards, MIBs, and RFCs
cable service flow inactivity-threshold
cable upstream unfrag-slot-jitter
show interface cable qos paramset
show interface cable downstream
show interface cable mac-scheduler
show interface cable service-flow
DOCSIS 1.1 for Cisco uBR7200 Series
Universal Broadband Routers
Cisco IOS Release 12.1(7)CX1
October 1, 2001
OL-0564-02
This document describes the support for version 1.1 of the Data Over Cable System Interface Specifications (DOCSIS) in Cisco IOS Release 12.1(7)CX1 for the Cisco uBR7200 series universal broadband routers. This document focuses on the new software and the changes to the existing software architecture that provide DOCSIS 1.1 support. This document also describes Cable Modem Termination System (CMTS) to Cable Modem interoperability and provides instructions for migrating from DOCSIS 1.0 to DOCSIS 1.1.
This document includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
DOCSIS 1.1 is the first major revision of the initial DOCSIS 1.0 standard for cable networks. Although the initial standard provided quality data traffic over the coaxial cable network, the demands of real-time traffic such as voice and video required many changes to the DOCSIS specification.
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Feature History
Table 1 summarizes the history of the DOCSIS 1.1 for Cisco uBR7200 series routers feature set.
Table 1 Cisco IOS 12.1 CX Feature History
12.1(4)CX
The DOCSIS 1.1 feature for Cisco uBR7200 series routers was introduced.
12.1(7)CX1
Several DOCSIS 1.1 MIBs were updated, reflecting changes in the DOCSIS 1.1 specification:
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The cable submgmt default command was also added, to set the default value of the attributes in DOCS-SUBMGT-MIB.
DOCSIS 1.1 Enhancements
The DOCSIS 1.1 specification provides the following functional enhancements over DOCSIS 1.0 coaxial cable networks:
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DOCSIS 1.1 Quality of Service
The DOCSIS 1.1 QoS framework is based on the following objects:
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In DOCSIS 1.1, the basic unit of QoS is the service flow, which is a unidirectional sequence of packets transported across the RF interface between the cable modem and CMTS. A service flow is characterized by a set of QoS parameters such as latency, jitter, and throughput assurances.
Every cable modem establishes a primary service flow in both the upstream and downstream directions. The primary flows maintain connectivity between the cable modem and CMTS at all times.
In addition, a DOCSIS 1.1 cable modem can establish multiple secondary service flows. The secondary service flows either can be permanently created (they persist until the cable modem is reset or powered off) or can be created dynamically to meet the needs of the on-demand traffic being transmitted.
Each service flow has a set of QoS attributes associated with it. These QoS attributes define a particular class of service and determine characteristics such as the maximum bandwidth for the service flow and the priority of its traffic. The class of service attributes can be inherited from a preconfigured CMTS local service class (class-based flows), or they can be individually specified at the time of the creation of the service flow.
Each service flow has multiple packet classifiers associated with it, which determine the type of application traffic allowed to be sent on that service flow. Each service flow can also have a Payload Header Suppression (PHS) rule associated with it to determine which portion of the packet header will be suppressed when packets are transmitted on the flow.
Figure 1 illustrates the mapping of packet classifiers.
Figure 1 Classification within the MAC Layer
Quality of Service Comparison
Quality of service (QoS) is a measure of performance for a transmission system that reflects its transmission quality and service availability. This section describes the differences in QoS between DOCSIS 1.0, 1.0+, and 1.1
DOCSIS 1.0
DOCSIS1.0 uses a static QoS model that is based on a class of service (CoS) that is preprovisioned in the TFTP configuration file for the cable modem. The CoS is a bidirectional QoS profile that has limited control, such as peak rate limits in either direction, and relative priority on the upstream.
DOCSIS 1.0 defines the concept of a service identifier (SID), which specifies the devices allowed to transmit and provided device identification and CoS. In DOCSIS 1.0, each cable modem is assigned only one SID, creating a one-to-one correspondence between a cable modem and the SID. All traffic originating from, or destined for, a cable modem is mapped to that cable modem's SID.
Typically, a DOCSIS 1.0 cable modem has one CoS and treats all traffic the same, which means that data traffic on a cable modem can interfere with the quality of a voice call in-progress. The CMTS, however, can prioritize downstream traffic based on IP precedent type-of-service (ToS) bits. For example, voice calls using higher IP precedence bits receive a higher queueing priority (but without a guaranteed bandwidth or rate of service). A DOCSIS 1.0 cable modem could increase voice call quality by permanently reserving bandwidth for voice calls, but then that bandwidth would be wasted whenever a voice call is not in progress.
DOCSIS 1.0+
In response to the limitations of DOCSIS 1.0 in handling real-time traffic, such as voice calls, Cisco created the DOCSIS 1.0+ extensions to provide the more important QoS enhancements that were expected in DOCSIS 1.1. In particular, the DOCSIS 1.0+ enhancements provide basic Voice-over-IP (VoIP) service over the DOCSIS link.
Cisco's DOCSIS 1.0+ extensions include the following DOCSIS 1.1 features:
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Caution
DOCSIS 1.1
DOCSIS 1.1 implemented a number of changes to allow great flexibility in the ability of a cable modem and service provider to transmit almost any combination of data traffic and real-time traffic, such as voice and video. These changes required a fundamental shift in how a cable modem requests service and how traffic can be transmitted across the cable network.
In DOCSSI 1.1, a service flow gets created at the time of cable modem registration (a static service flow) or as a result of a dynamic MAC message handshake between the cable modem and the CMTS (a dynamic service flow). At any given time, a service flow might be in one of three states (provisioned, admitted, or active). Only active flows are allowed to pass traffic on the DOCSIS link.
Every service flow has a unique (unique per DOCSIS MAC domain) identifier called the service flow identifier (SFID). The upstream flows in the admitted and active state have an extra Layer 2 SID associated with them. The SID is the identifier used by the MAC scheduler when specifying time-slot scheduling for different service flows.
When a packet is presented to the DOCSIS MAC layer at the CMTS or cable modem, it is compared to a set of packet classifiers until a matching classifier is found. The SFID from this classifier is used to identify the service flow on which the packet will be sent. The packet is then transferred to the service flow manager for rate shaping and output queueing.
In the upstream direction, the output queues at the cable modem get remotely served by the CMTS MAC scheduler, based on DOCSIS 1.1 slot scheduling constraints such as grant-interval and grant-jitter. In the downstream direction, the CMTS packet scheduler serves the flow queues depending on the flow attributes like traffic priority, guaranteed rate, and delay bound.
The principal mechanism for providing enhanced QoS is to classify packets traversing the RF MAC interface into service flows. A service flow is a MAC-layer transport service that provides unidirectional transport of packets to upstream packets transmitted by the cable modem or to downstream packets transmitted by the CMTS.
DOCSIS 1.1 adds several new MAC scheduling disciplines to provide guaranteed QoS for real-time service flows on the multiple access upstream channel. Multiple grants per interval helps in supporting multiple subflows (such as voice calls) on the same SID. Multiple subflows per SID reduces the minimum SID requirement in cable modem hardware.
The CMTS is responsible for supporting QoS for all cable modems in its control. The traffic in the downstream is assumed to be a combination of voice, committed information rate (CIR) data, and excess burst best-effort data. To provide QoS support, the following functions must be performed:
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The admission control block helps the overall downstream QoS block to track the current bandwidth reservation state on a per-downstream basis. Decisions can be made whether to admit or reject a request for a new service flow on that DS channel, based on this reservation state and the QoS guarantees requested by the new service-flow.
IP packet classifiers help in filtering out unique service flows on an interface for differential QoS treatment. Rather than doing per-cable modem downstream rate shaping, DOCSIS 1.1 software provides rate shaping at a much more granular level of individual service flows of the cable modem.
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DOCSIS 1.1 Features in Cisco IOS Release 12.1 CX
The following sections describe the DOCSIS 1.1 software features that appear in Cisco IOS Release 12.1 CX, including the commands used to implement the features.
Cable Modem Database Manager
The Cable Modem Database Manager is a new software module that manages cable modem information on the CMTS. This module can be queried to obtain different types of information on a single cable modem (or a group of cable modems). Information maintained on a per cable-modem basis includes DOCSIS MAC capabilities, counters, errors, QoS configuration, MAC state, connectivity statistics, and so on.
Commands
Router# show cable modemService Flow Manager
The Service Flow Manager is a new module that manages different activities related to service flows on a cable interface. Typical events include the creation of new DOCSIS service flows, modification of the attributes of existing service flows, and the deletion of service flows.
Commands
Router# show interface cable x/y service-flowRouter# debug cab qosService Template/Class Manager
The Service Template/Class Manager is a software module that controls the creation, updating, and cleanup of various QoS service templates and user-defined service classes on the CMTS.
Commands
Router# show cable service-classRouter# show int cx/y cable qos-paramsetRouter(config)# cable service class nRouter# debug cable qosTLV Parser/Encoder
The TLV parser/encoder is a new module that handles parsing and encoding TLVs on the CMTS. All old DOCSIS1.0/1.0+ TLVs are supported. In addition, many new TLVs have been added in DOCSIS1.1, such as service flow encodings, classifier encodings, and support for PHS rules. The new TLV parser features are used by different MAC message modules.
Commands
Router# debug cable tlvsEnhanced Registration
The registration module has been enhanced to support multiple registration styles (DOCSIS1.0/DOCSIS1.0+/DOCSIS1.1) seamlessly. Besides using services of new TLV parser/encoder, this module also supports the conditional registration-acknowledgment MAC message state machine.
Commands
Router# debug cable registrationRouter# debug cable tlvsDynamic MAC Messages
Dynamic Service MAC messages allow dynamic signaling of QoS between the cable modem and the CMTS. These messages are DOCSIS link layer equivalents of the higher layer messages that create, tear down, and modify a service flow. These messages are collectively known as DSX messages.
The DSX state machine module on the CMTS manages the several concurrent dynamic service transactions between cable modems and the CMTS. It include state machine support for all three DOCSIS1.1 DSX MAC messages:
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Commands
Router# debug cable dynsrvRouter# debug cable tlvs
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Fragmentation
Grant fragmentation allows the upstream MAC scheduler to slice large data requests to fit into the scheduling gaps between UGS (voice slots). This reduces the jitter experienced by the UGS slots when large data grants preempt the UGS slots. The grant fragmentation gets triggered in the MAC scheduler, and fragment reassembly happens in the upstream receive driver.
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Commands
Router# show interface cable x/y sid [n] counters [verbose]Router(config-if)# [no] cable upstream n fragmentationRouter# debug cable errorsPayload Header Suppression and Restoration
The PHS feature is used to suppress repetitive or redundant portions in packet headers before transmission on the DOCSIS link. This is a new feature in the DOCSIS1.1 MAC driver. The upstream receive driver is now capable of restoring headers suppressed by cable modems, and the downstream driver is capable of suppressing specific fields in packet headers before forwarding the frames to the cable modem.
Commands
Router# show interface cable x/0 service-flow [sfid] phsRouter# debug cable errorRouter# debug cable phsConcatenation
Concatenation allows the cable modem to make a single time-slice request for multiple packets and send all packets in a single large burst on the upstream. Concatenation was introduced in the upstream receive driver in the DOCSIS1.0+ releases. Per-SID counters have now been added in Cisco IOS Release 12.1(4)CX for debugging concatenation activity.
Commands
Router# show interface cable x/y sid [n] counters [verbose]Router# show controller cable x/yRouter(config-if)# [no] cable upstream n concatenationRouter# debug cable errorsNew MAC Scheduler
The MAC scheduler controls all time-slot assignment on the shared upstream channel. This block has been redesigned to support several new scheduling disciplines of DOCSIS1.1. Important enhancements include:
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All old Cisco features, such as dynamic contention control are supported in the new design.
Commands
Router# show interface cable x/y mac-scheduler nRouter(config-if)# [no] cable upstream n fragmentationRouter(config-if)# [no] cable upstream n unfrag-slot-jitterRouter# cable service flow inactivity-threshold nRouter# debug cable mac-schedulerDownstream Packet Classifier
Packet classifiers help to map packets into DOCSIS service flows. The CMTS supports downstream IP packet classifiers.
Commands
Router# show interface cable x/y classifierRouter# show interface cable x/y service-flow [n] classifiersRouter# debug cable qosDownstream Packet Scheduler
The Downstream Packet Scheduler is a new module that controls all output packet queueing service on the downstream link of each cable interface.
Commands
Router# debug cable qosRouter# show interface cable x/y downstreamBaseline Privacy Interface Plus
DOCSIS 1.0 included a Baseline Privacy Interface (BPI) to protect user data privacy across the shared-medium cable network and to prevent unauthorized access to DOCSIS-based data transport services across the cable network. BPI encrypts traffic across the RF interface between the cable modem and CMTS, and also includes authentication, authorization, and accounting (AAA) features.
BPI supports access control lists (ACLs), tunnels, filtering, protection against spoofing, and commands to configure source IP filtering on RF subnets to prevent subscribers from using source IP addresses that are not valid. For a detailed description of how BPI was implemented in DOCSIS 1.0, see the Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide.
DOCSIS 1.1 enhances these security features with BPI Plus (BPI+), which includes the following enhancements:
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Additional DOCSIS 1.1 Features in Cisco IOS Release 12.1(7)CX1
Cisco IOS Release 12.1(7)CX1 enhances DOCSIS 1.1 support with the following new or changed MIBs:
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In addition, the CLI supports a new command (cable submgmt default) to set the default value of attributes in DOCS-SUBMGT-MIB. This command can be included in the Cisco IOS configuration file so that the new values are automatically set after a reboot or reload of the Cisco uBR7200 series router.
Migrating from Earlier Versions of DOCSIS
DOCSIS 1.1 cable modems have additional features and better performance than earlier DOCSIS 1.0 and 1.0+ models, but all three models can coexist in the same network. DOCSIS 1.0 and 1.0+ cable modems will not hamper the performance of a DOCSIS 1.1 CMTS, nor will they interfere with operation of DOCSIS 1.1 features. There is full forward and backward compatibility in the standards.
Benefits
DOCSIS 1.1 includes a rich set of features that provide advanced and flexible QoS capabilities for various types of traffic (voice, data, and video) over the cable network. It also provides enhanced security and authentication features.
Baseline Privacy Interface Plus Enhancement
The Plus (+) version of the Baseline Privacy Interface (BPI+) in DOCSIS 1.1 provides a set of extended services within the MAC sublayer that increase performance and system security. Digital certificates provide secure authentication for each cable modem, to prevent identity theft on the basis of MAC and IP addresses. Advanced encryption provides a secure channel between the cable modem and CMTS, and secure software download allows a service provider to upgrade the software on cable modems, without the threat of interception, interference, or alteration of the software code.
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Dynamic Service Flows
The dynamic creation, modification, and deletion of service flows allows for on-demand reservation on Layer 2 bandwidth resources. The CMTS can now provide special QoS to the cable modem dynamically for the duration of a voice call or video session, as opposed to the static provisioning and reservation of resources at the time of cable modem registration. This provides a more efficient use of the available bandwidth.
Concatenation
The cable modem concatenates multiple upstream packets into one larger MAC data frame, allowing the cable modem to make only one time-slot request for the entire concatenated MAC frame, as opposed to requesting a time slot for each individual packet. This reduces the delay in transferring the packet burst upstream.
Enhanced QoS
Extensive scheduling parameters allow the CMTS and the cable modem to communicate QoS requirements and achieve more sophisticated QoS on a per service-flow level.
Different new time-slot scheduling disciplines help in providing guaranteed delay and jitter bound on shared upstream. Activity detection helps to conserve link bandwidth by not issuing time slots for an inactive service flow. The conserved bandwidth can then be reused for other best-effort data slots.
Packet classification helps the CMTS and cable modem to isolate different types of traffic into different DOCSIS service flows. Each flow could be receiving a different QoS service from CMTS.
Fragmentation
The MAC scheduler fragments data slots to fill the gaps inbetween UGS slots. Fragmentation reduces the jitter experienced by voice packets when large data packets are transmitted on the shared upstream channel and preempt the UGS slots used for voice. Fragmentation splits the large data packets so that they fit into the smaller time slots available around the UGS slots.
Multiple Subflows per SID
This feature allows the cable modem to have multiple calls on a single hardware queue. This approach scales much better than requiring a separate SID hardware queue on the cable modem for each voice call.
Payload Header Suppression
Payload Header Suppression (PHS) allows the CMTS/cable modem to suppress repetitive or redundant portions in packet headers before transmitting on the DOCSIS link. This helps to conserve link bandwidth, especially with types of traffic, such as voice, where the header size tends to be as large as the size of the actual packet.
Service Classes
The QoS attributes of a service flow can be specified in two ways: either explicitly by defining all attributes, or implicitly by specifying a service class name. A service class name is a string that the CMTS associates with a QoS parameter set.
The service class serves the following purposes:
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Any service flow can have its QoS parameter set specified in any of three ways:
· By explicitly including all traffic parameters.
· By indirectly referring to a set of traffic parameters by specifying a service class name.
· By specifying a service class name along with modifying parameters.
The service class name is expanded to its defined set of parameters at the time the CMTS successfully admits the service flow.
Restrictions
In addition to the interoperability issues listed here, the CMTS must be running Cisco IOS Release 12.1(4)CX or Cisco IOS Release 12.1(7)CX1 to support DOCSIS 1.1 and the cable modem must also support the DOCSIS 1.1 feature set.
Limitations
Cisco IOS Release 12.1(7)CX1 supports the features listed in the DOCSIS 1.1 specification SP-RFIv1.1-IO3-991105. Additional features will be supported as they are added to the specification and as the specification is finalized.
DOCSIS 1.1 traffic is supported on Cisco uBR-MC1xC and Cisco uBR-MC28C cable interface line cards. The Cisco uBR-MC11 (FPGA) and Cisco uBR-MC16B line cards do not support DOCSIS 1.1.
In particular, the following DOCSIS 1.1 features are not supported in Cisco IOS Release 12.1(7)CX1:
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In addition, 1+1 redundancy and the HCCP protocol are not supported during DOCSIS 1.1 operation.
Interoperability Issues
This section describes some of the differences between DOCSIS 1.0, DOCSIS 1.0 with extensions, and DOCSIS 1.1.
Baseline Privacy Interface Plus
BPI+ encryption and authentication must be supported and enabled by both the cable modem and CMTS. In addition, the cable modem must contain a digital certificate that conforms to the DOCSIS 1.1 and BPI+ specifications.
Also, ensure that the system clocks on the CMTS and on the time-of-day (ToD) servers are synchronized. If this does not occur, the clocks on the CMs will not match the clocks on the CMTS, which could interfere with BPI+ operations. In particular, this could prevent the proper verification of the digital certificates on the CM.
Maximum Burst Size
Previously, the maximum concatenated burst size parameter could be set to zero to specify an unlimited value. In a DOCSIS 1.1 environment, this parameter should be set to a nonzero value, with a maximum value of 1522 bytes for DOCSIS 1.0 cable modems.
If a cable modem attempts to register with a maximum concatenation burst size of zero, the DOCSIS 1.1 CMTS will refuse to allow the cable modem to come online. This avoids the possibility that a DOCSIS 1.0 cable modem could interfere with voice traffic on the upstream by sending extremely large data packets. Since DOCSIS 1.0 does not support fragmentation, transmitting such data packets could result in unwanted jitter in the voice traffic.
In addition, DOCSIS 1.1 requires that the maximum transmit burst size be set to either 1522 bytes or the maximum concatenated burst size, whichever is larger. Do not set the maximum concatenation burst size to values larger than 1522 bytes for DOCSIS 1.0 cable modems.
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Provisioning
The format and content of the TFTP configuration file for a DOCSIS 1.1 cable modem are significantly different from the file for a DOCSIS 1.0 cable modem. A dual-mode configuration file editor is used to generate a DOCSIS 1.0 style configuration file for DOCSIS 1.0 cable modems and a DOCSIS 1.1 configuration file for DOCSIS 1.1 cable modems.
Registration
A DOCSIS 1.1 CMTS is designed to handle the existing registration TLVs from DOCSIS 1.0 cable modems as well as the new type TLVs from DOCSIS 1.1 cable modems. A DOCSIS 1.0 and DOCSIS 1.1 cable modem can successfully register with the same DOCSIS 1.1 CMTS.
A DOCSIS 1.1 cable modem can be configured to make an indirect reference to a service class that has been statically defined at the CMTS instead of explicitly asking for the service class parameters. When this registration request is received by a DOCSIS 1.1 CMTS, it encodes the actual parameters of the service class in the registration response and expects a DOCSIS 1.1-specific registration-acknowledge MAC message from the cable modem.
When a DOCSIS 1.0 cable modem registers with a DOCSIS 1.1 CMTS, the registration request explicitly requests all nondefault service-class parameters in the registration. The absence of an indirect service class reference eliminates the need for the DOCSIS 1.1 TLVs and eliminates the need to establish a local registration acknowledge wait state.
When a DOCSIS 1.1 CMTS receives a registration request from a DOCSIS 1.0 cable modem, it responds with the DOCSIS 1.0 style registration response and does not expect the cable modem to send the registration-acknowledge MAC message.
Performance
DOCSIS 1.0 cable modems lack the ability to explicitly request and provide scheduling parameters for advanced DOCSIS 1.1 scheduling mechanisms, such as unsolicited grants and real-time polling. DOCSIS 1.1 cable modems on the same upstream channel can benefit from the advanced scheduling mechanisms and a DOCSIS 1.1 CMTS can still adequately support voice traffic from DOCSIS 1.1 cable modems with DOCSIS 1.0 cable modems on the same upstream channel.
Related Documents
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Supported Platforms
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Supported Standards, MIBs, and RFCs
Standards
DOCSIS 1.1 specification SP-RFIv1.1-IO3-991105
Baseline Privacy Interface Plus Specification BPI+_I06-001215
MIBs
For DOCSIS 1.1 the new supported MIBs are:
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This is revision 05 of this MIB and replaces the DOCS-BPI-MIB, which is supported only in DOCSIS 1.0. As required by the DOCSIS specifications, a DOCSIS 1.1 CMTS and CM support only the attributes in DOCS-BPI-PLUS-MIB and not the attributes in DOCS-BPI-MIB.
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Standard IGMP management MIB.•
This MIB was released as RFC 2669.•
Extends RFC 2669 (DOCS-CABLE-DEVICE-MIB).•
Extends RFC 2670 (DOCS-IF-MIB).In addition, the CLI supports a new command (cable submgmt default) to set the default value of attributes in DOCS-SUBMGT-MIB. This command can be included in the Cisco IOS configuration file so that the new values are automatically set after a reboot or reload of the Cisco uBR7200 series router.
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In addition, DOCS-IF-MIB (RFC 2670) has been modified.
RFCs
RFC 2669 (DOCS-CABLE-DEVICE-MIB)
Prerequisites
Before you power on and configure the CMTS:
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After these prerequisites are met, you are ready to configure the CMTS. This includes, at a minimum, configuring a host name and password for the CMTS and configuring the CMTS to support IP over the cable plant and network backbone.
Caution
Configuration Tasks
Perform the configuration tasks outlined in your CMTS documentation to configure the CMTS. When the Cisco uBR7200 series has been upgraded to Cisco IOS Release 12.1 CX, it automatically enables all DOCSIS 1.1 features and sets them to their default values.
Command Reference
This section documents new or modified commands. All other commands are documented in the Cisco IOS Release 12.1 and Cisco IOS 12.1 T command reference publications. The following commands are new or have been modified to accommodate DOCSIS 1.1 functionality.
New Commands
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Modified Commands
Debug and Test Commands
Replaced Commands
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cable dci-response
To configure how a cable interface responds to DCI-REQ messages for cable modems on that interface, use the cable dci-response command in cable interface configuration mode.
cable dci-response [success | ignore | reject permanent | reject temporary]
Syntax Description
Defaults
The Cisco CMTS responds to DCI-REQ messages from all cable modems by sending a DCI-RSP response with the confirmation code of Success (0).
Command Modes
Cable interface configuration
Command History
Usage Guidelines
The Device Class Identification (DCI) messages are part of the Media Access Control Specification section of the DOCSIS 1.1 specification (revision SP-RFIv1.1-I05-000714 and above). A cable modem (CM) can optionally use the DCI-REQ message to inform the CMTS of certain capabilities, such as whether it is a CPE-controlled cable modem (CCCM).
The CMTS then responds with one of the following confirmation codes:
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Examples
The following example shows how to configure the CMTS so that it ignores all DCI-REQ messages from cable modems on the cable interface at slot 6:
router# config trouter(config)# int c6/0router(config-if)# cable dci-response ignorerouter(config-if)#The following example shows how to configure the CMTS so that it returns to its default behavior for the cable interface on slot 6, which is to respond to all DCI-REQ messages from cable modems by sending a DCI-RSP with a Success confirmation code:
router# config trouter(config)# int c6/0router(config-if)# cable dci-response successrouter(config-if)#
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Related Commands
cable dci-upstream-disable
To configure a cable interface so that it transmits a DOCSIS 1.1 Upstream Transmitter Disable (UP-DIS) message to a particular cable modem (CM), use the cable dci-upstream-disable command in cable interface configuration mode. To remove that configuration and return to the default configuration, use the no form of this command.
cable dci-upstream-disable mac-address [enable | disable]
no cable dci-upstream-disable mac-address [enable | disable]
Syntax Description
Defaults
The Cisco CMTS does not transmit UP-DIS messages to any cable modems.
Command Modes
Cable interface configuration
Command History
Usage Guidelines
The DOCSIS 1.1 specification (revision SP-RFIv1.1-I05-000714 and above) allows a CMTS to transmit an Upstream Transmitter Disable (UP-DIS) message to a CM. If the CM supports the UP-DIS message, it responds by immediately disabling its upstream transmitter circuitry. The CM must be power-cycled before it can begin transmitting on the upstream again.
Examples
The following example shows that the UP-DIS message is being enabled for the CM with the MAC address of 0123.4567.89ab.
router# config trouter(config)# int c6/0router(config-if)# cable dci-upstream-disable 0123.4567.89ab enablerouter(config-if)#Related Commands
Configures how the cable interface responds to DCI-REQ messages from cable modems on that interface.
Enables debugging of DCI-REQ, DCI-RSP, and UP-DIS messages.
cable service class
To set parameters for cable service class, use the cable service class command in global configuration mode.
cable service class class_index [keyword-options]
Syntax Description
Defaults
Values that are not specified are set to their DOCSIS 1.1 defaults, if applicable to the service-class schedule type.
Guest
