1. Virtual Signaling Transfer Point User Guide
  2. vSTP Features
  3. SLS Rotation
  4. Combining SLS Rotation Options

2.12.5 Combining SLS Rotation Options

In order to provide an even distribution of ITU and ANSI messages sent by M3RL, vSTP allows to combine the Random SLS, Use of Other CIC Bit, Incoming Bit Rotation, and Outgoing Bit Rotation options in the following manner:

ITU Messages

If a user activates the above options for a given linkset, then the ITU SLS field is processed in the following order:

  1. If the randsls parameter value is set as ON, then 8-bit random SLS is generated.

    Note:

    Random SLS of ITU is based on either the global option or outgoing linkset parameter. For more details on Random SLS, see SLS Rotation.

  2. If the global slscnv or slsci parameters for outgoing linkset are ON, then the 4-bits ITU SLS is converted to 8-bits SLS using 4-to-8 Bit SLS Conversion option.

  3. If it is an ITU-ISUP message, then the least-significant 4-bits of the modified SLS are modified using the Other CIC Bit option.

  4. The least-significant 4-bits of the modified SLS are modified using Incoming Bit Rotation or Outgoing Bit Rotation.

  5. The modified SLS is used by the existing linkset and link selection algorithms to select a linkset and link.

  6. The Message is sent out to the selected link containing the original and unmodified SLS field.

For ANSI Messages

If a user activates these options for a given linkset, then the ANSI SLS field is processed in the following order:

  1. If the randsls parameter value is set as ON, then 8-bit random SLS is generated.

    Note:

    Random SLS of ANSI is based on the incoming linkset parameter with the value of global option set as is PerLs. For more details on Random SLS, see SLS Rotation.

  2. If RANDSLS is applied and the system-wide slsreplace parameter value is true, then the randomly generated SLS is replaced in the MSU and Step 5 is executed.

  3. If the global slscnv or slsci parameters for outgoing linkset are ON, then the 5-bits ANSI SLS is converted to 8-bits SLS using 5-to-8 Bit SLS Conversion option.

  4. If Random SLS is not applied, then the converted SLS is modified using the Incoming Bit Rotation option.

  5. The modified SLS is used by the existing linkset and link selection algorithms to select a linkset and link.

  6. The SLS is modified using standard 5th bit rotation, replaced in the MSU and sent out to selected link.