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New and existing cable subscribers select the services they desire and provide information about their computer equipment. Cisco Subscriber Registration Center (CSRC) combines this information with cable network configuration information to create a configuration profile for each subscriber's equipment. These profiles ensure that each time subscribers turn on their computers and cable modems, the proper network addresses are assigned and the proper configuration files are transferred to the subscribers' equipment. The cable modems are automatically configured to support the services the subscribers selected.
As the cable network administrator, you define the services that network devices and applications support, and you define a variety of quality-of-service levels. You then bundle the service levels into service packages. You can then use the User Registrar component of CSRC to manage the aspects of your service offerings that are visible to the subscriber (for example, the service name, description, and price), and associate these with the corresponding service package.
You can use Modem Registrar to dynamically generate DOCSIS configuration files, based on configuration information that you define. To help you effectively manage your installation, you need to understand the concepts and specifications that Modem Registrar implements. This chapter discusses each of the following concepts:
The Data-Over-Cable Systems Interface Specification (DOCSIS) is a specification written by leading North American cable operators, CableLabs, and their vendor representatives.
DOCSIS version 1.0 is the base cable modem standard from CableLabs. This version is sufficient for general Internet access.
DOCSIS version 1.1 is a superset of DOCSIS 1.0. It includes extensions to support enhanced quality of service for applications such as IP telephony.
Modem Registrar supports the options for both DOCSIS versions 1.0 and 1.1. The new options for DOCSIS 1.1 include options 22, 23, 24, 25, 26, 28, and 29.
You can define the services that network devices and applications support. For example, the following are typical services that you might define:
Based on these services, you can use Modem Registrar to do the following:
A service type is a component of a service that you offer your subscribers. For each service type defined, you also define various levels and qualities of service called service levels. You can define as many service levels for a service type as needed.
For example, Table 2-1 lists example service types and levels that you might define for specific services.
| Service | Service Type | Service Levels |
|---|---|---|
Browsing the Web | Browsing speed | High Medium Low |
Voice over IP | Quality of sound | Telephone Broadcast Digital CD |
Home networking | Devices-supported | 1 5 20 |
A service tuple is a service type and level pair. For example, the service tuple data-bandwidth=10 Mbps consists of the service type data-bandwidth and the service level 10 Mbps.
Table 2-2 lists additional service types and levels that you might define, based on your service offerings.
| Service Type | Service Level | Service Type Description |
|---|---|---|
Data-bandwidth | 10 Mbps 2 Mbps 512 Kbps 256 Kbps | Data bandwidth offerings. |
Min-traffic-rate | Best High Medium Low | Minimum traffic rate offerings. |
Devices-supported | 4 3 2 1 | Number of supported devices. |
For information on configuring service types and levels, see "Configuring Service Types" section.
A service class is a collection of service types required for a specific service you offer. Each service class includes the attributes and values that define the type or quality of service associated with a given class. You can specify more than one service type for each service class.
For example, Table 2-3 lists service classes you might define based on your offering to subscribers.
| Service Class | Service Class Description |
|---|---|
Data | Required types for data service. |
Voice | Required types for voice service. |
Diskspace | Required types to specify disk space allotment. |
You might specify the following service types for the service class called data only:
You can define the precedence order for the service types included in a service class. When the TFTP server assembles option values to generate a DOCSIS configuration file, the server uses the precedence order of service types to determine which value of an option to use. Modem Registrar assigns the highest precedence order to the first service type listed for the class and the lowest precedence order to the last service type listed for the class.
For example, Table 2-4 lists the service types you might define for the service class called data. On the Modem Registrar page, the service types are listed in the order shown in the table. The data-bandwidth service type has the highest precedence because it appears first in the list of service types. The devices-supported service type has the lowest precedence because it appears last in the list.
| Service Class: Data |
|---|
| Service Types |
Data-Bandwidth (highest precedence) |
Devices-Supported |
Network-Access (lowest precedence) |
For more information about precedence order, see the "Precedence Order of Scopings" section and the "Precedence Order in Option Sets" section.
For information about configuring service classes, see the "Configuring Service Classes" section.
A service package characterizes a quality of service a subscriber can select. For example, Table 2-5 lists the service packages you might define based on the qualities of service you offer.
| Service Package | Service Package Description |
|---|---|
Basic Student | Limited service |
Family Plus | Premium service |
Internet | Standard service |
Each service package requires that you specify a single service class on which to base the service package. Each service class can become the template for one or more service packages.
The service class has one or more service types associated with it and each service type has one or more service levels associated with it. When you create a service package, you select the service level you want to implement for each service type.
The service types for each service class have a precedence order that you defined in the service class. The precedence order determines which value of an option the TFTP server uses in a cable modem's DOCSIS configuration file. For more information about precedence order, see the "Precedence Order of Scopings" section and the "Precedence Order in Option Sets" section.
Table 2-6 lists three sample service packages you might offer your subscribers: Basic Student, Family Plus, and Premium. Each of these packages is associated with the service class, types, and levels indicated in the table. The service types are listed in the highest to lowest precedence order.
| Service Package | Service Class | Service Type=Service Level | Service Package Description |
|---|---|---|---|
Basic Student | Data | Data-bandwidth=10 Mbps Min-traffic-rate=medium Devices-supported=1 | Limited service |
Family Plus | Data | Data-bandwidth=10 Mbps Min-traffic-rate=high Devices-supported=5 | Premium service |
Platinum | Data | Data-bandwidth=10 Mbps Min-traffic-rate=best Devices-supported=4 | Deluxe service |
For information about configuring service packages, see the "Configuring Service Packages" section.
Option set scopings are special purpose units, containing option sets and DOCSIS options for which you specify a value. The TFTP server uses the DOCSIS options in each scoping to generate the cable modem configuration file.
You configure the option set scopings from the most general scoping to the most specific scoping. The default scoping is the most general scoping that you can configure. It contains the DOCSIS options that apply to all cable modems. Typically, you will assign most of the DOCSIS options values to the more general scopings since these scopings apply to most cable modems in your installation.
The cable modem scoping is the most specific scoping that you can configure. It contains the DOCSIS options that apply only to a specific cable modem. Typically, you will assign fewer DOCSIS option values to the specific scopings since these scopings apply only to special cases.
The following lists the option set scopings from most general to most specific:
For more information about each of the option set scopings you can configure, see the following sections.
For more information about the option set scopings internal to Modem Registrar, see the "Option Set Scopings Internal to Modem Registrar" section.
The default scoping is used to define the DOCSIS options that apply to all cable modems in your installation. This scoping is the most general scoping you can configure. It consists of the default option set, a pre-defined option set that you can modify. Typically, the default option set is more densely populated with DOCSIS options than the other more specific option sets that you define for special cases.
For information about configuring the default option set, see "Configuring the Default Option Set."
The CMTS group scoping is an optional scoping used to manage groups of CMTS devices. The CMTS group scoping may contain multiple option sets for which you define DOCSIS options. Each CMTS group option set may have multiple CMTS scopes assigned to it, allowing you to manage these systems at the group level instead of individually. The group level can refer to one or more headends or distribution hubs.
For information about configuring the CMTS group option set, see the online Help information for the CMTS group option set pages.
The CMTS scoping is a required scoping used to manage the CMTS devices that communicate with cable modems in your installation. The CMTS scoping should contain an option set for each CMTS device in your installation. At a minimum, Modem Registrar requires that you define at least one CMTS option set.
You can assign DOCSIS options to a CMTS option set; however, Modem Registrar does not require you to do so.
For information about configuring the CMTS option set, see "Configuring CMTS Option Sets."
The subnet scoping is a required scoping used to associate a subnet with its servicing CMTS. The subnet scoping models your physical installation and must contain an option set for each subnet in your installation. At a minimum, Modem Registrar requires that you define at least one subnet option set.
You can assign DOCSIS options to a subnet option set; however, Modem Registrar does not require you to do so.
For information about configuring the subnet option set, see "Configuring Subnet Option Sets."
The vendor scoping is an optional scoping used to manage cable modems manufactured by specific vendors. The vendor scoping can contain an option set for each vendor's cable modem in your installation. Modem Registrar does not require you to define vendor option sets.
You can assign DOCSIS options to a vendor option set; however, Modem Registrar does not require you to do so.
For information about configuring the vendor option set, see "Configuring Vendor Option Sets."
Under special circumstances, you might need to configure individual options for a particular cable modem. The cable modem scoping is an optional scoping used to manage individual cable modems. You create a cable modem option set for each particular cable modem you choose to configure.
The cable modem might have an associated vendor option set, depending on whether the vendor prefix in the modem's MAC address is associated with a vendor option set. The TFTP server checks the first six hexadecimal digits of the modem's MAC address for the vendor prefix. If present, the TFTP server uses the associated vendor option set when assembling DOCSIS options for the cable modem.
The cable modem has a service associated with it that is chosen by the subscriber or the administrator. This service selection indicates the service package for the cable modem. The TFTP server uses the service package to determine which options from the relevant option set scopings to apply to the cable modem. The TFTP server also uses dynamically generated option values from the dynamic cable modem scoping when assembling the DOCSIS configuration file.
You can use the options you define in the cable modem option set scoping to modify the options you defined in other scopings. Because cable modem option sets are more specific, the TFTP server uses the options you define in cable modem option sets instead of those defined in other option set scopings, unless a suppress rule applied to an option in a less specific scoping prevents the TFTP server from using the option defined in the cable modem option set.
The number of cable modem option sets you define can be quite large if you define an option set for each cable modem in your installation. For this reason, you will typically want to use cable modem option sets sparingly and for only special circumstances.
For information about configuring cable modem option sets, see the online Help information for the cable modem pages.
The option set scopings discussed in the following sections are internal to Modem Registrar. You cannot configure these scopings.
The DOCSIS specifications distinguish between mandatory options and excluded options. Mandatory options are those options that must be included in configuration files. For example, option 3 must appear in either DOCSIS version 1.0 or version 1.1 configuration files.
Excluded options are those options that apply only to a particular DOCSIS version. These options must be excluded from configuration files that are generated for another DOCSIS version. For example, options 22 through 29 must not appear in version 1.0 configuration files.
The DOCSIS version scoping is a built-in scoping internal to Modem Registrar. This scoping contains option sets with pre-defined options for DOCSIS version 1.0 and version 1.1. Mandatory options and excluded options are defined using option rules. For more information, see the "Option Rules" section.
Modem Registrar allows you to specify DOCSIS version 1.0 and version 1.1 options for all option set scopings. The TFTP server uses the DOCSIS version scoping to assemble only those options that are appropriate for a particular cable modem. When you examine the list of all options applied to a particular cable modem, the options assembled from the DOCSIS version scoping are identified as coming from the DOCSIS 1.0 or DOCSIS 1.1 option set, or a DOCSIS hybrid option set.
You cannot modify the option sets in the DOCSIS version scoping. Options defined in more specific option sets, such as vendor option sets, may override the mandatory options in the DOCSIS version option sets. However, mandatory options may not be suppressed; Modem Registrar will include them in the DOCSIS configuration file. More specific option sets cannot override or suppress excluded options.
The dynamic cable modem scoping is a temporary option set scoping that is defined as the TFTP server assembles the DOCSIS configuration file.
The dynamic cable modem scoping consists of a dynamic option set that contains the following options:
You can also override an option defined in the dynamic cable modem scoping by assigning the option in the option sets of other less specific scopings. To do this, in the less specific scoping, you must first apply the replace rule to the option and then apply the suppress rule.
The Modem Registrar user interface provides a flexible method for customizing DOCSIS configuration files. To simplify the configuration process, Cisco recommends that you define option sets for the most general to the most specific option set scopings. The following lists the order in which Cisco recommends you create option sets within the scopings:
As you move from general to specific scopings, DOCSIS options are more sparsely assigned. For example, the default option set contains the options that apply to all cable modems, while the cable modem option set, if it exists, contains the options that apply only to that cable modem.
At a minimum, you must create option sets for the following option set scopings, in the order listed:
1. Default option set scoping---The default option set scoping makes it easier to manage options that apply to all cable modems in your installation. You do not create the default option set. However, you must assign options to it.
2. CMTS option set scoping---The CMTS option set scoping is required to identify the CMTS that services cable modems.
3. Subnet option set scoping---The subnet option set scoping is required to identify the CMTS with which cable modems on that subnet communicate.
You can also create the following option sets, but Modem Registrar does not require you to do so.
The precedence order determines which value of an option is applied to a cable modem. Options defined in the most specific option set scopings take precedence over the same options defined in more general scopings. If an option defined in the default scoping is also defined in other more specific scopings, the TFTP server uses the value of the option in the most specific scoping. For example, options defined in the CMTS scoping take precedence over options defined in the default scoping.
The option rule assigned to an option determines how that option is treated when the TFTP server encounters the same option in more specific scopings. For more information, see the "Option Rules" section.
Within each option set you can define options that are common to all service types and levels, or that apply to a specific service type and level. Within an option set, the TFTP server assembles options specified in the common options, unless the same option is specified in a service type and level chosen in the cable modem's service package.
If a particular service tuple (service type and level) is part of the service package associated with the cable modem, the options defined in an option set for the specific service tuple have a higher precedence order than do the common options defined in the option set. When the same option is defined for both the common options and for a specific service tuple, the TFTP server uses the value of the option defined for the service tuple.
If the cable modem does not have an associated service package (it is unprovisioned), the TFTP server uses the value of the option defined in the common options.
For example, assume that the service chosen for the cable modem is associated with the Basic Student package. Table 2-7 lists the service types and levels defined for this package. The service tuples are listed in the highest to lowest precedence order (for example, data-bandwidth=10 Mbps has the highest priority)
| Service Type | Service Level |
|---|---|
| |
| |
| |
Option 4.1 is defined in the common options and for the following two service tuples in the Basic Student package (see Table 2-8):
data-bandwidth=10 Mbps min-traffic-rate=medium
The TFTP server determines which value of option 4.1 to use based on precedence order. In Table 2-8, the service tuple data-bandwidth=10 Mbps has the highest precedence order as defined by the Basic Student package (see Table 2-8). The service tuple min-traffic-rate=medium has the second highest precedence order and the common options have the lowest precedence order.
| CMTS Option Set: abacus.cisco.com | Option | Value | Rule |
|---|---|---|---|
Data-bandwidth=10 Mbps | 4.1 | 1 | Replace |
Min-traffic-rate=medium | 4.1 | 2 | Replace |
Common options | 4.1 | 16 | Replace |
The DOCSIS options you define in option sets are classified as one of the following categories:
The option category is used in combination with the option instances (see the "Single-Instance and Multi-Instance Options" section) to determine the options that you can configure for an option set.
In addition to options being simple or compound (see the "Option Categories" section), options can also be single-instance or multi-instance. If only one copy of an option can be defined in the option set, the option is single-instance. If more than one copy of an option can be defined, the option is multi-instance.
Option sets can contain the following single-instance and multi-instance options:
The option category (see the "Option Categories" section) and the option instances are used to determine the options that you can configure for an option set.
The TFTP server can assemble the suboptions of a single-instance compound option from more than one option set. When this occurs, the option is said to be split across the option sets from which it will be assembled. All single-instance compound options are splitable.
For example, option 15 (Telephone Settings) is a splitable option. The TFTP server might assemble suboptions 15.7 (Username) and 15.8 (Password) from an individual cable modem option set scoping and assemble other suboptions of option 15 from other more general option set scopings.
Each DOCSIS option defined in an option set has an option rule associated with it. The TFTP server assembles options from the most general to the most specific option set scopings. When it encounters the same option in a more specific option scoping, it uses the option rule to determine how to treat the option.
The option rules are the following:
The category of an option and whether the option is a single-instance or multi-instance option determine which option rules you can associate with the option and how the TFTP server interprets the rules. The following sections discuss the rules for single-instance and multi-instance options, and the way in which the TFTP server interprets the available rules.
For more information on option categories, see the "Option Categories" section.
For more information on single-instance or multi-instance options, see the "Single-Instance and Multi-Instance Options" section.
The following rules are available for single-instance options, both simple and compound. The replace rule is the default.
Within a single option set, you can specify only one replace rule for a single-instance simple option number, and at most you can specify only one replace rule for any of the suboptions of a single-instance compound (splitable) option. If you choose the suppress rule, you can specify only one per single-instance simple option number and at most one for any of the suboptions of a single-instance compound (splitable) option.
The TFTP server interprets the option rules for single-instance simple options and single-instance compound options as follows:
The following rules are available for multi-instance options, both simple and compound. The replace rule is the default.
Within a single option set, you may specify the following:
The TFTP server interprets the option rules for multi-instance simple options and multi-instance compound options as follows:
Table 2-9 shows the options available for specific categories (simple and compound) and instances (single-instance and multi-instance), and it indicates the option rules (replace, append, and suppress) that can be applied.
| Category | Single-Instance | Multi-Instance | ||
|---|---|---|---|---|
Simple | Options | Rules | Options | Rules |
1, 2, 3, 9, 18, 19, 20, 21, 28, 29 | 10, 11, 14 | Replace (all instances) Append (add a complete instance) Suppress (all instances) | ||
Compound | 15, 17 | (applicable to individual suboptions) Replace Suppress | 4, 22, 23, 24, 25, 26, 43 | Replace (all instances) Append (add a complete instance) Suppress (all instances) |
Posted: Fri Oct 15 12:37:08 PDT 1999
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