Using the PPPTRACE Utility

The PPPTRACE utility enables you to debug PPP data link problems. PPPTRACE fully decodes and displays PPP protocol exchanges. You can also examine network protocol data that flows through the PPP link in a partially decoded format. Because each captured frame is time stamped to an accuracy of one tenth of a second, PPPTRACE can also provide valuable timing information.

This topic describes the interface for PPPTRACE. You can use PPPTRACE to perform the following tasks:

• Observe real-time samples of data as it flows through the PPP interface.
• Capture the PPP protocol exchanges and troubleshoot any PPP connectivity problem. You can display and capture every LCP and NCP protocol exchange. This lets you pinpoint the cause of failure for a PPP connection, including the following:
  • Failure to negotiate LCP options
  • Failure to negotiate NCP options
  • Failure to authenticate a user or remote system ID
  • Delays in replying to LCP/NCP requests and verification of consequent retransmissions
  • Isolate problems as belonging to the hardware driver or the PPP data link

• Capture to RAM (fast capture) or to disk (for viewing at a later time on the same or different machine)
• Examine raw packet data in ASCII or hexadecimal format
• Switch monitoring among different PPP interfaces by pressing a single key

To start PPPTRACE, type the following command at the server prompt:

load ppptrace

The PPPTRACE Available Options menu enables access to the features of PPPTRACE. These features are described in Table 11 .

Table 11. PPPTRACE Options

Note that the Real-Time Monitor does not show all the frames on the display. Instead, it shows a sampling of frames and ignores the frames that came in while the display of a frame was in progress. If you capture the output to a disk file or RAM and display it later, all frames that were processed by the PPP interfaces are displayed.

WARNING:  The Real-Time Monitor can consume a large portion of your router CPU resources.

For example, a status value of [Raw Mode, Short, Hex] tells you that the data is being shown in Raw Mode (no decode of any PPP frames), Short Display (one line of data), and Hex. Use function keys F3 , F4 , or F5 to change any of the three configuration parameters dynamically.

WARNING:  When Multilink is used, all data frames are shown only on the first member of the Multilink group, though LCP packets are still shown for each link.

The Real-Time Monitor provides its functions through the following keys:

F2 ---Enables you to select an interface. Identify your interface (LSL board number) by viewing the port status window in NWCCON.

F3 ---Toggles the display between Raw Mode (no decode of any PPP frames) or Decode Mode (PPP frames fully decoded).

F4 ---Toggles the display between complete and short display format.

F5 ---Toggles the display between Hex or ASCII format.

F6 ---Enables you to freeze and resume the continuous display of data.

F7 ---Enables you to begin and stop capturing the continuous display of data to either a disk file or to RAM.

F8 ---Goes to next interface.

F9 ---Returns to preceding interface.

Using PPPDISP

PPPTRACE works with PPPDISP to provide a way to analyze the output of PPPTRACE. PPPDISP is a DOS executable utility that decodes the PPPTRACE output file and generates an ASCII format file. PPPDISP.EXE is located in SYS:SYSTEM\UTILS.

For example, to write the captured data to an output file to display in ASCII, complete mode, and frame mode, enter the following command:

PPPDISP source_filename destination_filename

If the destination filename is not specified, data is displayed on the console server window. The contents of the source file are converted so that they are displayed in ASCII or hex format, in complete or short display mode, and in one of three decode modes: raw, frame, or packet mode. Table 12 shows the arguments that can be used with this DOS executable file. These arguments are case-sensitive.

Table 12. PPPDISP Arguments