In this section:

You can configure some additional attributes for ANSI-specific features such as Link Craft Referral, False Link Congestion, and Circular Route Detection Test (CRDT). For information about how to configure the CRDT, refer to Configuring the Circular Route Detection Test.

For additional information about these attributes, see GR-246-CORE issue 10 T1.111.4 section 12.2 and 12.3 and GR-82-CORE section 4.2.4.10.1.

Configuring T19 Notification

The T19 Notification attribute affects the behavior of the ANSI Link Craft Referral timer (ANSI T19). If this attribute is set to ENABLED, the system logs each T19 expiry event after unsuccessful activation of an SS7 link. If this attribute is set to DISABLED, no system logs are generated when an SS7 link fails to come into service within T19.

Configuring the T19 Link Reset

The T19 Link Reset attribute affects the behavior of the ANSI Link Craft Referral timer (ANSI T19). If this attribute is set to ENABLED, the link is reset after each expiry of the T19 timer. If this attribute is set to DISABLED, the link is not reset after the expiry of T19 timer.

Configuring the T19 Attempts

This T19 Attempts attribute affects the behavior of the ANSI Link Craft Referral timer (ANSI T19). If this attribute is set to FOREVER, the timer runs forever until the link is activated. After each expiry of the timer, the link is either reset or is continually activated depending on the T19 Link Reset attribute setting (see Configuring the T19 Link Reset).

If this attribute is set to ZERO, the timer is disabled and does not run.

If this attribute is set to ONE, the link activation is stopped and the link is deactivated after the first T19 expiry.

If this attribute is set to TWO or THREE and if the T19 Link Reset attribute is set to ENABLED, the link reset continues forever.

If this attribute is set to TWO or THREE and if T19 Link Reset attribute is set to DISABLED, the link is activated for one or two periods of T19 duration depending on the selection. The timer stops the link activation and deactivates the link after the last T19 expiry.

Configuring the T31 False Link Congestion

The T31 False Link Congestion attribute affects the behavior of the L3 False Link Congestion timer (ANSI T31).

If this attribute is set to DISABLED_ALL_CONGESTION_LEVELS, the timer does not run.

If this attribute is set to ENABLED_ALL_CONGESTION_LEVELS, the timer is started whenever the link congestion level changes to a value greater than Level 0. The timer is restarted on every change of congestion level between Level 1, Level 2 and Level 3. When the congestion level drops to Level 0, the timer is canceled. If the timer expires or is canceled, the link is restarted.

If this attribute is set to ENABLED_ALL_EXCEPT_LEVEL1, the congestion Level 1 is not considered for starting and restarting the timer. If the congestion level changes to Level 2 or Level 3, the timer is started. The timer is restarted whenever the congestion level changes between Level 2 and Level 3. When the congestion level drops to Level 1 or Level 0, the timer is canceled. If the timer expires or is cancelled, the link is restarted.

The timer value originates from the timer T31 and should be in the range of 10 000 milliseconds to 120 000 milliseconds. The default attribute value is 30 000 milliseconds. Whenever the link is restarted due to expiry of the timer, then the management is notified by the system log.

Configuring the CRDT Support

The CRDT Support attribute provides support for the ANSI Circular Route Detection Test (CRDT). The ANSI CRDT procedure is supported on ANSI STPs, as per GR-246-CORE Issue 10 T1.111.7 (Method A) and GR-82-CORE Issue 10. The CRDT procedure may be explicitly enabled or disabled for ANSI STPs using this attribute. If the SS7 Variant is not set to ANSI, or if the STP Routing feature is not enabled then this attribute has no effect. Setting this attribute to DISABLED resets the state of all routes that were marked as prohibited for failing a CRDT test.

The three configurable attributes (N, M, and Timer Loop) in the ANSI CRDT method A are defined as follows:

  • When congestion status increases on a link, sample N MSUs (range 50-200) sent on that link.

  • From the N MSUs, compute the M most common Destination Point Codes (DPCs), range 3-10).

  • Send test messages to those destinations.

  • If a test message comes back within CRDT Timer Loop (10 - 20s) then there is a loop in the MTP3 routing tables in the network. Disable the tested routes and those of lower priority.

Configuring the NTT Unallocated Signaling Point Number (USN) Support

The NTT USN Support attribute provides USN support for the NTT and TTC SS7 Variants. This attribute is ENABLED and not configurable for NTT, configurable for TTC with default DISABLED, and is DISABLED and not configurable for other SS7 variants.

If the NTT USN Support is ENABLED, an MTP3 NA that receives a SRT with an unknown Destination Point Code is answered with an USN sent to the SRT originator on the incoming link instead of the usual TFP.

To configure the SS7 Variant Specific Configuration attributes

  1. From the Main Menu, click MTP3.

  2. Click the NA you want to configure.

  3. Click SS7 Variant Specific Configuration.
      

  4. Configure the attributes.

    Tip

    The Restore Debug Defaults action restores the MTP3 NA logging configurations to their default values and clears the associated logging alarms.

  5. Click Continue.

 

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