Notice on Rectification for SDH Trail Interruption on the U2000

Summary: The SDH(Huawei network product distributor) trail management window displays two trails with the same source or/and sink. A user regards one of them as a duplicate or useless service and deactivates it, which causes interruption of unrelated trails.

[Problem Description]
Trigger conditions:
SDH trail search is performed on one client while SDH trail creation is performed on another client simultaneously.
This problem also occurs on a single client if a user creates an SDH trail when automatic SDH trail search is in progress.
Fault symptom:
The SDH trail management window displays two trails with the same source or/and sink (NEs, ports, and timeslots). In this situation, the following fault symptoms occur:

• When a user queries the cross-connections of the two trails, cross-connections are displayed only for one of them or only some cross-connections are displayed for bothof them.
•  If user-defined information is configured, the information is displayed only for one of them.
•  If the trails are VC4 server trails, client trails can be queried only for one of them or only some client trails can be queried for both of them.

Deactivating any one of the trails will cause interruption of unrelated trails.
Identification method:

• Automatic: See the Readme file in the attached tool package.
• GUI-based: Check the SDH trail management window for two trails with the same source or/and sink.

[Root Cause]
1. When trail search begins, the U2000 loads network-wide trails to the memory for comparing them with those found after the search. Based on the comparison, the U2000 determines whether there are new trails.
2. Before trail search begins, the U2000 divides NEs into different areas. During trail search, the U2000 loads cross-connections area by area. As shown in the schematic diagram, the trail search starts from area A. Within this period, a user creates trail X between an NE in area B and another NE in area C.
3. When the trail search proceeds to areas B and C, the cross-connections of trail X form trail X+.
4. Trail X does not exist at the beginning. Therefore, the U2000 determines that trail X+ is a new trail and saves it to the database.
5. Trail X and trail X+ coexist in the database and use the same source and sink. Either trail X or trail X+ has no cross-connection.
6. It is also possible that trail X and trail X+ use the same source or sink and both of them have only some cross-connections, which depends on the timing of the search and creation.

[Impact and Risks]
After a user deactivates one of the two trails with the same source or/and sink, the other trail is unexpectedly interrupted as well as the client trails of the other trail.

[Measures and Solutions]

Recovery measures:

•  Upgrade the current U2000 to one of the following patch versions or a later version:

T2000 V200R007C03SPC108, U2000 V100R002C01CP5131, U2000 V100R003C00CP1052, U2000 V100R005C00 CP6031, U2000 V100R006C00CP2001, U2000 V100R006C02SPC300

• If you do not want to install a patch, delete the duplicate trails from the network(Huawei transport network) layer and search for network-wide SDH trails. Ensure that trail creation is not performed during the search. The tool attached in this document can find duplicate trails.

Workarounds:

• Search for SDH trails when trail creation is not performed.
•  Delete the existing duplicate trails from the network layer and search for network-wide SDH trails to restore the desired trail. Do not deactivate a trail directly.
•  Do not deactivate trails in batches.

If deactivation has been performed, verify that service interruption does not occur before deleting a trail.

Solutions:
Search for network-wide SDH trails after installing one of the following patches:

• T2000 V200R007C03SPC109
•  U2000 V100R002C01CP5032 (in offices that require security rectification)
•  U2000 V100R002C01CP5033 (in offices that do not require security rectfication)
•  U2000 V100R005C00CP6137
•  U2000 V100R006C00CP3102
•  U2000 V100R006C02SPC301

This tool (a script) can check the existence of trails with the same source or/and sink on the U2000. To successfully execute the tool, you are required to enter the password for the database user sa. The tool creates three temporary tables and one store procedure during a check and deletes them after the check is complete. The tool does not modify any user data. After a check is complete, the tool returns the names of duplicate trails.