DOCSIS Configuration

This chapter describes the provisioning flow in a Broadband Access Center (BAC) DOCSIS deployment. It also provides information required before configuration and describes the available tools.

•DOCSIS Workflow

•Using MIBs with Dynamic DOCSIS Templates

•BAC Features for DOCSIS Configurations

•Troubleshooting DOCSIS Networks

Note See DOCSIS Option Support, page 8-15, for information on DOCSIS options supported by this
BAC release.

DOCSIS Workflow

Figure 4-1 shows the provisioning workflow contained in the DOCSIS Provisioning Specification. Each step is described subsequently.

Figure 4-1 DOCSIS Provisioning Flow

Table 4-1 describes the potential problems that can exist at various DOCSIS provisioning steps illustrated in Figure 4-1.

Table 4-1 DOCSIS Workflow Description 

Step
DOCSIS Workflow
Potential Problems

CM1 -1

DHCP Discover

•The init(d) state

•No addresses available

•Incorrect BAC shared secret

•Incorrectly configured Class of Service

•DOCSIS template parsing errors (invalid option, include file - not found, and so on)

Network Registrar DHCP

•Incorrect DHCP configuration

•DHCP server not there in provisioning group

BAC Network Registrar Extension

•Network Registrar extension cannot contact DPEs

•Network Registrar extension fails to find any DPEs in provisioning group

•Verify extensions are connected to the RDU

•Network Registrar extension gets DPE cache miss, sends request to RDU

RDU

•No appropriate scopes defined (or do not match BAC RDU configuration)

•Incorrect RDU IP address

•Incorrect RDU port (default 49187)

•RDU cannot be pinged from DPE

•Configuration generation is failing at the RDU

•RDU licenses exceeded, not configured

•Device detection is failing at the RDU

DPE

•DPEs not assigned to provisioning group

•DPEs cannot be pinged from the DHCP server

•DPE interfaces not enabled for provisioning

CM-2

DHCP Offer

Routing issues between DHCP and CMTS2

CM-3

DHCP Request

init(i) state

DHCP server did not provide all the parameters required

CM-4

DHCP Ack

 

CM-5

TFTP Request

•Init(o) state

•Routing issues between CMTS and DPE

•No route from TFTP server (DPE) to modem

•DPE cache miss (static file, and RDU down or does not have file)

•File not found at TFTP server (DPE)

•DPE cache miss (dynamic file)

•DPE IP validation failure (for example, the IP address of the device is not what was expected, the Dynamic Shared Secret is enabled on CMTS, or a hacker is spoofing as a DOCSIS modem)

CM-6

TFTP Response

Routing issues between DPE and CMTS

CM-7

ToD Request

init(t) state - No route from time server (DPE) to modem

CM-8

ToD Response

 

CM-9

CM registration with CMTS

•reject(m) - * CMTS shared secret mismatch with BAC or DPE DOCSIS shared secret

•reject(c) - * delivered incorrect DOCSIS configuration file (1.1 file to 1.0 CM)

CM-10

CMTS registration Ack

Acceptable states are:

•online

•online(d)

•online(pk)

•online(pt)

1 CM = cable modem

2 CMTS = cable modem termination system


Using MIBs with Dynamic DOCSIS Templates

For a full list of MIBs that BAC ships with, see SNMP VarBind, page 8-5.

Two versions of the DOCSIS MIB are loaded into the RDU:

•DOCS-CABLE-DEVICE-MIB-OBSOLETE (experimental branch)

•DOCS-CABLE-DEVICE-MIB (mib2 branch)

For information on how to use them, see DOCSIS MIBs, page 8-5.

You can add MIBs using an API call or by modifying rdu.properties. For more details, see Configuring Euro PacketCable MIBs, page 5-30.

You can add SNMP TLVs to a template:

•When no MIB is available. See Adding SNMP TLVs Without a MIB, page 8-8.

•With vendor-specific MIBs. See Adding SNMP TLVs With Vendor-Specific MIBs, page 8-9.

BAC Features for DOCSIS Configurations

This section describes BAC value-added features as they relate to the DOCSIS technology.

Dynamic Configuration TLVs

The DPE adds the following TLVs when it receives a TFTP request for dynamic DOCSIS configuration:

•TLV 19: TFTP Server Timestamp (optional)—Displays in the Configure DOCSIS Defaults page as the TFTP Time Stamp Option. See Table 11-4 for more information. This TLV requires NTP synchronization on CMTS and DPE.

•TLV 20: TFTP Server Provisioned Modem Address (optional)—Displays in the Configure DOCSIS Defaults page as the TFTP Modem Address Option. See Table 11-4 for more information.

Note This feature is incompatible with the Cisco CMTS DSS feature. If DSS is set on the Cisco CMTS, you must ensure that the TFTP Server Provisioned Modem Address is disabled.

•TLV 6: CM MIC Configuration Setting (required)

•TLV 7: CMTS MIC Configuration Setting (required)—Displays in the Configure DOCSIS Defaults page as the CMTS Shared Secret. See Table 11-4 for more information.

Note When configuring CMTS MIC, note the following CMTS IOS release dependencies:

•DOCSIS 2.0 CMTS MIC requires CMTS IOS 12.3BC when including TLV 39 or TLV 40.

•Certain CMTS IOS commands are assumed to be configured by BAC:

–ip dhcp relay information option

–no ip dhcp relay information check

–cable helper-address x.x.x.x

where x.x.x.x is the IP address of the Network Registrar DHCP server.

–cable dhcp-giaddr primary

DPE TFTP IP Validation

For dynamic configuration files, the DPE TFTP server verifies if the IP address of the TFTP client matches the expected DOCSIS cable modem IP address. If it does not match, the request is dropped. This feature is incompatible with the Cisco CMTS DMIC feature.

Use the no tftp verify-ip command to disable the verification of requestor IP addresses on dynamic configuration TFTP requests. For detailed information, refer to the Cisco Broadband Access Center DPE CLI Reference, 2.7.1.

DOCSIS 1.0, 1.1, 2.0 Support

BAC 2.7.1 supports DOCSIS 1.0, 1.1, and 2.0. See Support Tools and Advanced Concepts, page 13-1, for information describing the TLVs and options that this BAC release supports in each DOCSIS version.

Dynamic DOCSIS Version Selection

BAC can detect a cable modem's DOCSIS version from an incoming DHCP request. It can also detect the CMTS DOCSIS version from a customer-supplied source that provides a mapping of GIADDR to the CMTS DOCSIS version.

Using this information, BAC, if so configured, determines the optimum DOCSIS configuration file for the device. This is the highest common DOCSIS version between the device and the CMTS. For example, if the device supports DOCSIS 2.0 and the CMTS supports DOCSIS 1.1, the DOCSIS 1.1 file is used.

Note You can specify the DOCSIS version by using the Configuration File Utility. For more information, see Using the Configuration File Utility, page 8-27. This function that the file utility performs is different from RDU verification, during which the RDU DOCSIS Version Selector feature determines the latest DOCSIS version supported by a CMTS.

DOCSIS Configuration File Based on DOCSIS Version

The following Class of Service properties are supported by the BAC administrator user interface and the API: 

/cos/docsis/file/1.0

/cos/docsis/file/1.1

/cos/docsis/file/2.0

Optionally, you can add these properties to a DOCSIS Class of Service to associate a DOCSIS configuration filename with a particular DOCSIS version. Each of these properties (if set) causes the RDU to establish a database relationship between the Class of Service and the file named by the property value, as is done for the existing DOCSIS configuration filename property.

GIADDR-Based Dynamic DOCSIS Version Selection

During configuration generation, the service-level selection extension for DOCSIS modems looks for the /docsis/cmts/version/giaddrToVersionMap property. The value of this property is the name of an external file containing a mapping of the GIADDR to the DOCSIS version supported by the cable modem. This mapping file must be named giaddr-docsis-map.txt.

Note You can add the giaddr-docsis-map.txt to the RDU:

•From the API via the Configuration.addExternalFile() call.

•From the administrator user interface via Configuration > External Files. See Adding External Files, page 11-27.

The giaddr-docsis-map.txt file must include the necessary information in the following format:

IPv4_address DOCSIS_version

•IPv4_address—IPv4 address of the CMTS interface

•docsis_version—DOCSIS version that the cable modem supports

For example, if the CMTS interface had IP address 10.30.0.1 with DOCSIS version 1.0, the file would include: 

10.30.0.1 1.0

Note If the device GIADDR is not found in the mapping file, the extension uses the value of the /docsis/cmts/version/default property for the DOCSIS version of the cable modem. The default value of this property is 1.0.

To dynamically update the giaddr-docsis-map.txt file, edit it and replace it in the RDU via the replaceExternalFile API or via the administrator user interface.

Note If the properties for the DOCSIS version selection are not specified on the Class of Service, the original file is used, allowing for systematic upgrades across the network.

Troubleshooting DOCSIS Networks

For information on troubleshooting the DOCSIS technology with respect to BAC and the Cisco uBR7246 CMTS, refer to Troubleshooting uBR Cable Modems Not Coming Online at:
http://www.cisco.com/en/US/tech/tk86/tk89/technologies_tech_note09186a0080094eb1.shtml