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The following section is only applicable to the DSC 8000. For more information, see Limitations for DSC Platforms.

The Sonus Signaling System allow you to enable remote loop back on a single LSL Channel (DS0 Level) within one port on the T1 or E1 interface card without affecting traffic on the other channels on this port. This process is useful to verify the integrity of the signaling path internal to the I/O card.

If the Sonus Signaling Systems are connected to a node in remote loopback mode, link alignment fails at MTP3 because the SLTM/SLTA exchange fails. If the circuit path is well established, the links cycle through MTP2 alignment (L2 proving then L2 in service then L3 failure). MTP3 does not go into service until the loopback is removed.


Initiation of a loopback on a channel causes this LSL Channel to go out of service. However, traffic on all the other LSL Channels on the same port and interface card is not affected. The LSL Channel is unavailable for use while a loopback is enabled on this link.

The Sonus Signaling Systems support the following loopback features for the LSL Channels on a port at DS0 level:



To remove an applied loopback, you must manually set the Loopback Mode attribute to DISABLED (see To apply or remove a remote loopback on an LSL Channel).

The following figure shows the signal path local loopback for an LSL Channel.

Figure : Loopback on an LSL Channel (DSC)

To apply or remove a remote loopback on an LSL Channel

  1. From the Main Menu, click the required card on the Sonus Signaling System image.

  2. Click the required I/O card.

  3. Click the LSL channel that you want to loopback.

  4. Click the required LSL channel.

  5. In the Loopback Mode drop-down list, select the required option.

  6. Click Continue.


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