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Data-Over-Cable Systems Interface Specification (DOCSIS) cable modems require precisely specified configuration files. The options specified in the configuration files apply to specific cable modems and are influenced by the network to which the cable modem is connected and the set of hardware between the subscriber and the headend. While Solaris-based systems provide standard TFTP service, its configuration capabilities are inadequate for configuring cable modems. Windows NT does not provide any TFTP services.
To meet the configuration requirements of cable modems, Modem Registrar enhances the Cisco Network Registrar (CNR) TFTP server with dynamic configuration capabilities. This server replaces the TFTP server available on Solaris systems. Before using Modem Registrar, you must disable all existing TFTP services on the host on which the Cisco Network Registrar TFTP server is installed to avoid overlapping of services.
The Cisco TFTP server provides the following capabilities:
This chapter explains how to control TFTP server activities and to configure TFTP server settings.
You can use the Configure TFTP Server page (see Figure 4-1) to control TFTP server activities and to configure TFTP server settings. Typically, you only need to define these policies once, although you can choose to modify them at a later time.
You can manage the following TFTP activities and settings:
You can use the Control TFTP Server page (see Figure 4-2) to control the following TFTP server activities:
To control TFTP server activity, do the following:
Step 1 Log in to Modem Registrar (see the "Logging In to Modem Registrar" section).
Step 2 On the Main Menu page, click TFTP Server.
Step 3 On the Configure TFTP Server page, click Control.
Step 4 On the Control TFTP Server page, click the button for the activity you want to control.
You can use the Configure Bootstrap Settings page (see Figure 4-3) to set parameters for the external interface to the LDAP Server. The bootstrap settings you specify enable the TFTP server to communicate with the appropriate LDAP Server.
To configure bootstrap settings, do the following:
Step 1 Log in to Modem Registrar.
Step 2 On the Main Menu page, click TFTP Server.
Step 3 On the Configure TFTP Server page, click Bootstrap.
Step 4 On the Configure Bootstrap Settings page, enter the LDAP server's DNS name or IP address in the LDAP Hostname or IP Address field.
Step 5 In the LDAP Port field, enter the port number reserved for the LDAP Server. The default is 389.
Step 6 In the LDAP Username and LDAP Password fields, enter the administrator username and password you use to log in to the LDAP server.
Step 7 In the LDAP Root DN field, enter the root distinguished name (DN) for the CSRC configuration.
Step 8 Select the LDAP Use SSL checkbox if you want the TFTP server to use the Secure Sockets Layer (SSL) security when communicating with the LDAP server.
Step 9 In the LDAP Initial Communication Timeout field, enter the number of seconds you want to allow the TFTP server to initially attempt to communicate with the LDAP Server.
Step 10 In the LDAP Maximum Communication Timeout field, enter the maximum number of seconds you want to allow the TFTP server to re-attempt (re-try) to communicate with the LDAP server.
Step 11 Click OK to save the information. The Configure TFTP Server page appears.
You can use the Configure TFTP Settings page (see Figure 4-4) to control standard TFTP file services, such as file access and communication timeouts.
To configure TFTP settings, do the following:
Step 1 Log in to Modem Registrar.
Step 2 On the Main Menu page, click TFTP Server.
Step 3 On the Configure TFTP Server page, click TFTP.
Step 4 On the Configure TFTP Settings page, enter the TFTP home directory in the Home Directory field. This is the TFTP directory that you want the TFTP server to use to resolve relative paths for data files. For example:
Step 5 For Windows NT systems, select the drive letter that you want the TFTP server to use when a drive letter is not specified in the path being considered. The Default Drive Letter pull-down list displays drives C through Z. If you do not specify a drive letter, Windows NT uses the drive on which the Windows NT operating system is installed.
If your system is not running Windows NT, you must leave the Default Drive Letter field blank. The UNIX version of TFTP server ignores this setting.
Step 6 For the Directory Access field, select the Use Home Directory as Root checkbox if you want the TFTP server to use the home directory as root when resolving absolute and relative paths to allow access to files. Alternate directories that you specify are ignored.
Selecting the Use Home Directory as Root checkbox allows access to only paths that resolve to existing files beneath the home directory. You must use the UNIX directory delimiter ( / ) for both Windows NT and UNIX paths.
For example, consider the following configuration settings:
Using the example configuration, the home directory C:/program files/network registrar/data/tftp is effectively equivalent to the path C:/. Therefore, paths, such as the following access the file pathname in the directory C:/program files/network registrar/data/tftp:
This behavior is the same for UNIX systems, except the drive letter specification is omitted.
Step 7 In the Alternate Directories edit box enter the alternate directory paths that you want the TFTP server to use to allow access to absolute paths that are not contained in the home directory. You may specify up to 32 alternate directory strings, one directory per line. Each line must end with RETURN, delimiting the end of each path. The default is NULL.
For example, consider the following configuration settings:
Specifying alternate directories resolves relative paths to the following:
Absolute paths, such as the following resolve to C:/DUMP/pathname:
Absolute paths, such as the following resolve to D:/TFTP/pathname:
The path /TFTP/pathname is not allowed because the drive letter substituted is C and not D. The relative path /TFTP/pathname resolves to C:/TFTP/pathname, not to D:/TFTP/pathname.
Step 8 Select the Access Mode checkbox for the type of requests you want the TFTP server to service.
Step 9 In the Maximum File Size field, enter the maximum file size in kilobytes that you want the TFTP server to write to the local disk. The default maximum file size is 1024 KB.
Step 10 In the Initial Retransmission Time field, enter the number of seconds you want the TFTP server to wait for a response before initially retransmitting the same packet. You must enter a positive integer. The default is five seconds.
Step 11 In the Session Timeout field, enter the number of seconds you want the TFTP server to continue retransmitting packets before terminating the TFTP session. You must enter a positive integer. The default is 60 seconds.
Step 12 In the DOCSIS Pathname Prefix field, enter the root path that the TFTP server will use to signal a DOCSIS configuration file generation request. The TFTP server retrieves this prefix during startup as one of its DOCSIS configuration parameters. The default is /docsis.
The DOCSIS pathname prefix is used only when you enable DOCSIS access and starts DOCSIS file generation for a TFTP read request whose path matches this prefix. Home directory and alternate directories are searched only when the DOCSIS prefix does not match the pathname in the TFTP read request.
Step 13 Click OK to save the information you entered. The Configure TFTP Server page appears.
You can use the Configure Advanced Settings page (see Figure 4-5) to do the following:
To configure advanced settings, do the following:
Step 1 Log in to Modem Registrar.
Step 2 On the Main Menu page, click TFTP Server.
Step 3 On the Configure TFTP Server page, click Advanced.
Step 4 On the Configure Advanced Settings page, select the Log DOCSIS Configuration Files checkbox if you want to save DOCSIS configuration files as physical files on the TFTP server's disk. You can find these files in the CNR logs directory under TFTP.
If you do not select the Log DOCSIS Configuration Files checkbox, DOCSIS configuration file information is stored in memory only until the configuration file has been transmitted successfully to the requesting cable modem.
Step 5 In the Maximum Number of Configuration Files to Log field, enter the maximum number of log files you want to save on the TFTP server's disk. You must enter a positive integer and you must have selected the Log DOCSIS Configuration Files checkbox in the previous step. The default is 100.
Step 6 Select the Log Level radio button for the type of information you want the TFTP server to save in the log files. The default is Errors, Warnings, and Information.
Step 7 Select the Trace Level radio button for the type of trace information you want the TFTP server to save in the log files about incoming and outgoing TFTP packets. The default is none. Trace information is written to the file_tftp_1_trace file in the CNR logs directory.
Step 8 Click OK to save the information you provided. The Configure TFTP Server page appears.
Posted: Tue Aug 17 09:17:35 PDT 1999
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