2.12.4 Random SLS

If the Random SLS option is selected, then vSTP randomly generates SLS values. This randomly generated SLS value is then used to select an outgoing linkset and a link in order to achieve load balancing.

This option is applicable to all the ITU SCCP (Class 0 and Class 1), ANSI SCCP Class 0, and ANSI ISUP messages.

For this option, the system-wide randsls parameter provides the flexibility to provision Random SLS value as Off, Class0, All (Class0 & Class1), or PerLs . The Per-Linkset randsls parameter can provide the additional flexibility to apply Random SLS generation on per linkset basis. User shall be able to provision specific linksets with Random SLS value as Off, Class0, or All (Class0 & Class1).

For ANSI MSUs, randsls is applied based on the configuration for ingress linkset . For ITU MSUs, it is applied based on the configuration for egress linkset .

• ITU Messages
  For ITU, this option is available system-wide as well as on per linkset basis. The following table describes the rules applied on incoming MSU when Random SLS option is selected for ITU:

  Table 2-13 Rules applied for Random SLS for ITU

  System-wide randsls ( in m3rloptions)	randsls on outgoing linkset	Random SLS
  Off	Has No Impact	Random SLS is not applied on any ITU message.
  All	Has No Impact	Random SLS is applied on all ITU SCCP messages.
  Class0	Has No Impact	Random SLS is applied on all ITU SCCP CLASS0 messages.
  PerLs	Off	Random SLS is not applied on any ITU message going through this linkset .
  PerLs	All	Random SLS is applied on all ITU SCCP messages going through this linkset .
  PerLs	Class0	Random SLS is applied on all ITU SCCP CLASS0 messages going through this linkset .

• ANSI Messages
  For ANSI, this option is available on per linkset basis only. The following table describes the rules applied on incoming MSU when Random SLS option is selected for ANSI:

  Table 2-14 Rules applied for Random SLS for ANSI

  System-wide randsls ( in m3rloptions)	randsls on outgoing linkset	Random SLS
  Off	Has No Impact	Random SLS is not applied on any ANSI message.
  All	Has No Impact	Random SLS is not applied on any ANSI message.
  Class0	Has No Impact	Random SLS is not applied on any ANSI message.
  PerLs	Off	Random SLS is not applied on any ANSI message going through this linkset .
  PerLs	All	Random SLS is applied on ANSI SCCP Class0 and ISUP messages going through this linkset .
  PerLs	Class0	Random SLS is applied on all ANSI SCCP CLASS0 messages going through this linkset .

Note:

The SLS modified using the above options is used for internal linkset and link selection only. The actual SLS field of the message does not get modified. Therefore, the SLS value received by vSTP remains the SLS value sent out by the vSTP.