1. Virtual Signaling Transfer Point
  2. Overview of vSTP
  3. Stateful Application Feature
  4. Stateful Security Dynamic Learning
  5. Call Flow in Active Mode

2.8.4.3 Call Flow in Active Mode

This mode enables the following actions:

  • Learning of new VLRs. The status of existing VLRs get changed as per success or failure counts.
  • Handling the dynamic VLRs based on their status. The following table describes the dynamic VLRs with status and respective results:
    Status Result
    Whitelist Validation Success.

    VLR validation is not performed

    Blacklist Validation Failure
    Graylist VLR validation is not performed
    Note:
    • Success and Failure validation count is incremented based on validation result.
    • The GrayListed dynamic VLRs status can change to Whitelisted or Blacklisted
    Successful Validation Count When the net successful validation count reaches threshold, then VLR status is changed to Whitelisted.

    Note: success count - failure count >= success threshold

    Failure Validation Count When the net failure validation count reaches threshold, then VLR status is changed to Blacklisted.

    Note: failure count - success count > = failure threshold

VLR Validation in Active Mode

The following figure shows the vSTP call flow for VLR validation in active mode:

Figure 2-20 VLR Validation in Active Mode


img/vlr-validation-active-mode.png

  1. If the VLR is available in DPT or Whitelist Profile Table (WPT) as whitelist, then the validation is successful and LocUpdate is sent to HLR.
  2. In case the VLR is available in DPT as blacklist, then the message is rejected.
  3. If DPT entry is GL, then VLR validation is performed.
  4. If entry does not exists, then create new entry in DPT (as learn mode is also enabled in active mode).
  5. If entry is GL or entry doesn't exists in DPT, then perform validation such as lookup in UDR.
    • If IMSI record is found in UDR, then extract VLR from UDR response.
    • If record is not found in UDR then, send ATI to HLR and extract VLR from ATI ACK.
  6. If old and new VLRs are same, then validation is success, otherwise the validation is failed.
  7. Move VLR to BL/WL based on the threshold value, validation result, and raised event.
  8. On successful validation, send CreateorUpdate event to UDR.

Velocity Check in Active Mode

The following figure shows the vSTP call flow for Velocity check in active mode:

Figure 2-21 Velocity Check in Active Mode


img/velocity-check-active-mode.png

  1. If old and new VLRs are not same, then perform velocity check.
  2. If the status of the old VLR Blacklisted, then entry is not created in DPT. The velocity check results in Validation Failure.
  3. Perform lookup in DRT for old and new VLR combination. If entry exists and learning is complete (velocity_threshold exceeds), then perform velocity check using the entry.
  4. If no DRT entry is available, then create entry using long/lat table time and perform velocity check using that DRT entry. Update UDR if validation is successful. Also update VLR success or failure count, based upon the validation result.
  5. If entry is available but learning is not complete, then take time from LONG/LAT table and reset the time also with LonG/Lat table Time and Perform velocity check and VLRs count based upon the result.
  6. Update UDR if validation is successful.