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Voice Feature Guide 01

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
VBD Fault Diagnosis

VBD Fault Diagnosis

This topic describes the purpose and implementation principles of the voice band data (VBD) fault diagnosis feature.

NOTE:

Based on your requirements, VBD fault diagnosis may obtain some contents of users' communications (the information cannot restore the integrity communications contents) for the purpose of safeguarding network operations and protecting services. Huawei alone is unable to collect or save the content of users' communications. You must comply with the laws and regulations of the countries concerned for using the VBD fault diagnosis feature. You are obligated to take considerable measures to ensure that the content of users' communications is fully protected when the content is being used and saved.

Introduction

The VBD fault diagnosis feature enables the OLT to obtain voice packets, signaling packets, and voice control packets when a narrowband service fault occurs on the OLT. Then, O&M engineers can use these packets for rapid fault location. The narrowband service fault can be:
  • Poor quality of voice communication
  • High failure ratio of the fax or modem service
  • One-way audio or no audio
NOTE:
Voice control packets contain higher-layer communication protocols used between the control board and service boards of the OLT as well as digital signal processor (DSP) commands for processing internal board data.
The VBD fault diagnosis feature supports:
  • Remote fault location: removes the need of onsite fault location.
  • Rapid fault location: enables O&M personnel to obtain voice packets, signaling packets, and voice control packets based on fault symptoms, thereby improving fault location efficiency.
  • Intelligent fault locating: Intelligently associates with the packet capturing tasks, which lowers skills required for maintenance personnel and simplifies operations.
  • Secure and reliable data obtaining: The obtained voice packets, signaling packets, and voice control packets do not contain any user privacy information, such as called numbers, names, short messages, or frequency shift keying (FSK) data.

Networking Applications

Figure 1-152 shows the networking of the voice VBD fault diagnosis feature.

Figure 1-152 Networking of the VBD fault diagnosis feature

Carrier's administrator grants packet capturing rights to the O&M personnel. Then, the O&M personnel capture packets on a specified PC (packet capturing server). The OLT filters out users' communication content from the captured packets, encapsulates the filtered packets into UDP packet payloads, and sends the UDP packets to the PC.
NOTE:
Authorized packet capturing complies with local laws and regulations and is performed carrier's authorization. Authorized packet capturing is used to capture voice packets, signaling packets, and voice control packets that do no contain user sensitive information and the captured data is only used for fault location.

Figure 1-153 shows the process of obtaining voice packets.

Figure 1-153 Process of obtaining voice packets

  1. The carrier's administrator uses the administrator account to remotely log in to the OLT from the PC and grants packet capturing rights to the O&M personnel.
  2. The O&M personnel enable a general voice packet capturing tool, such as wireshark, on the PC, use a non-administrator account to remotely log in to the OLT, capture voice packets through the maintenance port.
    NOTE:
    To safeguard network operations and protect services, the O&M personnel can use only a non-administrator account to log in to the OLT.
  3. The OLT sends the obtained voice packets to the PC.
  4. The O&M personnel stop capturing voice packets.
  5. The carrier's administrator cancels the packet capturing permission.

Basic Concepts Related to Authorized Media Stream Packet Capturing

Capturing all voice packets of a call easily discloses user privacy information. To protect user privacy, the OLT provides differentiated VBD fault diagnosis modes. By doing so, VBD fault diagnosis can be enabled without bringing the risk of disclosing user privacy information.

Table 1-22 lists the VBD fault diagnosis modes that the OLT provides.
Table 1-22 VBD fault diagnosis modes

Mode

Description

Usage Scenario

Full packet capturing

The OLT does not filter or replace any information in the captured Real-Time Transport Protocol (RTP) or time division multiplexing (TDM) tracing packets.

This mode applies when the captured packets do not contain the content of users' communications. In this mode, packets can be captured as many as possible, which facilitates fault location. This mode is used to diagnose fax or modem negotiation failures.

Fuzzy packet capturing

The OLT retains the minimum data that identifies the fax or modem signal tone in RTP and TDM tracing packets, which prevents the original content of users' communications from being restored. Specifically, the OLT retains only 10 ms of data (data generated in a 10-millisecond duration) from every 80 ms of data and erases the 70-ms data. In this way, packets are captured in a discontinuous way and the original content of users' communications cannot be restored.

This mode applies when the OLT cannot determine whether a user will initiate a VBD call, or when the content of users' communications will be transmitted after a VBD call is set up. This mode is used when the local or peer end cannot identify a fax or modem signal tone or a fax or modem negotiation between the local and peer ends fails.

Packet header-only capturing

The OLT captures only the IP, UDP, and RTP headers of RTP packets. It replaces the payloads of the RTP packets with fixed data. In addition, the OLT does not capture TDM tracing packets.

This mode applies when the VBD negotiation process ends. This ensures that no content of users' communications will be captured. This mode is used to locate voice quality faults, such as packet loss, jitter, delay, one-way audio, and no audio.

Working Principles of Authorized Media Stream Packet Capturing

Figure 1-154 and Figure 1-155 show the application of the voice packet capturing modes in a fax or modem call and in a common call (Taking the local ringback tone as an example).

Figure 1-154 Application of the voice packet capturing modes in a fax or modem call

Figure 1-155 Application of the voice packet capturing modes in a common call

For the calling party:
  1. After the calling party picks up the phone, the OLT starts the full packet capturing mode.
  2. After detecting the first dual tone multiple frequency (DTMF) number, the OLT switches to the packet header-only capturing mode, which prevents disclosure of the user DTMF numbers.
  3. When the calling party hears ringback tones, the capturing mode does not changed.
  4. After the call is set up between the calling and called parties, the OLT switches to the fuzzy packet capturing mode and starts a fuzzy packet capturing protection timer (35s). The fuzzy packet capturing protection timer limits the fuzzy packet capturing duration and protects user communication security.
    NOTE:
    The call may be a VBD call, during which the VBD signal tone may not be identified. Therefore, the fuzzy packet capturing mode is required to locate faults where the VBD signal tone fails to be identified.
  5. If the OLT detects the fax or modem signal tone and the two ends of the fax or modem service are at the negotiation phase, the OLT switches to the full capturing mode because no communication data is involved at the negotiation phase. In this way, the OLT can capture most fault-related packets, which facilitates rapid fault location.
    NOTE:
    This step is involved only in a fax or modem call.
  6. Before the negotiation phase ends, the OLT switches to the fuzzy packet capturing mode.
    NOTE:
    This step is involved only in a fax or modem call.
  7. When the fuzzy packet capturing protection timer times out, the OLT switches to the packet header-only capturing mode, which protects user communication security.
For the called party:
  1. When the phone of the called party rings, the OLT starts the full packet capturing mode.
  2. When sending FSK data to the called party, the OLT switches to the packet header-only capturing mode, which prevents the content of users' communications from being captured.
  3. After the call is set up between the calling and called parties, the OLT switches to the fuzzy packet capturing mode and starts a fuzzy packet capturing protection timer (35s). The fuzzy packet capturing protection timer limits the fuzzy packet capturing duration and protects user communication security.
    NOTE:
    The call may be a VBD call, during which the VBD signal tone may not be identified. Therefore, the fuzzy packet capturing mode is required to locate faults where the VBD signal tone fails to be identified.
  4. If the OLT detects the fax or modem signal tone and the two ends of the fax or modem service are at the negotiation phase, the OLT switches to the full capturing mode because no communication data is involved at the negotiation phase. In this way, the OLT can capture most fault-related packets, which facilitates rapid fault location.
    NOTE:
    This step is involved only in a fax or modem call.
  5. Before the negotiation phase ends, the OLT switches to the fuzzy packet capturing mode.
    NOTE:
    This step is involved only in a fax or modem call.
  6. When the fuzzy packet capturing protection timer times out, the OLT switches to the packet header-only capturing mode, which protects user communication security.
NOTE:
When detecting the first DTMF number (or an RFC 2833-compliant DTMF number), the OLT switches to the packet header-only capturing mode to protect the numbers dialed by users.

Working Principles of Authorized Signaling Packet Capturing

Figure 1-156 shows the application of authorized signaling packet capturing.

Figure 1-156 Application of authorized signaling packet capturing

After authorized signaling packet capturing is enabled, the OLT performs the following operations on the signaling packets, such as SIP, MGCP, or H.248 packets, received from the softswitch/IP multimedia subsystem (IMS) or received by the OLT:
  1. Filters packets based on ports. The OLT captures the signaling packets only on the ports with signaling packet capturing enabled.
  2. Filters out sensitive personal information, including phone numbers, names, short messages, FSK data, and DTMF data, from the captured signaling packets.
  3. Encapsulates the signaling packets into UDP payloads in the format of "ETH header+IP header+UDP header+signaling" and sends the UDP payloads to the PC.

The O&M personnel enable a general voice packet capturing tool, such as wireshark, on the PC to capture voice packets and analyze the voice packets for fault location.

Working Principles of Authorized Voice Control Packet Capturing

Figure 1-157 shows the application of authorized voice control packet capturing.

Figure 1-157 Application of authorized voice control packet capturing

After authorized voice control packet capturing is enabled, OLT performs the following operations on the packets transmitted between the control board and service boards or between service boards:
  1. Converts voice control data into bit data in the same format.
  2. Filters out sensitive personal information, including phone numbers, names, short messages, FSK data, and DTMF data, from the captured voice control packets.
  3. Encapsulates the voice control packets into UDP payloads in the format of "ETH header+IP header+UDP header+voice control data" and sends the UDP payloads to the PC.

The O&M personnel enable a general voice packet capturing tool, such as wireshark, on the PC to capture voice packets and analyze the voice packets for fault location.

Configuration Procedure

Perform the following steps to capture voice packets:
  1. Run the remote-capture whitelist add command to add a specified user port on the PC to the remote packet capturing whitelist.

    Only the ports in the remote packet capturing whitelist can be used to capture voice packets.

    NOTE:
    The carrier's administrator must grant the operation rights to the O&M personnel for this step.
  2. Run the remote-capture parameters command to set the IP address and port number of the PC where voice packets can be captured.
  3. Run the remote-capture trace command to configure the port or channel for capturing packets and the packet capturing duration, and start voice packet capturing.
  4. Run the undo remote-capture trace command to manually stop capturing voice packets.
  5. After capturing voice packets, run the remote-capture whitelist delete command to delete the user port from the remote packet capturing whitelist.

Configuration Results

After the configuration, you can:
  • Run the display remote-capture state command to query packet capturing status on the port.
  • Capture voice packets on the PC where the general voice packet capturing tool, such as wireshark, is enabled.
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Updated: 2019-02-22

Document ID: EDOC1100067358

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