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    Storing Topology Discovery Table Data in Mirrored Storage

    You can enable storage of topology discovery table data in mirrored storage by using the persist-discovery-data enable command. By default, the storage of topology discovery table data in mirrored storage is enabled.

    The topology discovery table is used to store digital subscriber line (DSL) parameters in the router. Based on the DSL parameters, quality-of-service (QoS) shaping for each subscriber is determined. When two devices such as the Broadband Remote Access Server (B-RAS) and digital subscriber line access multiplexer (DSLAM) are synchronized on the basis of the agreed capabilities, the DSLAM sends port-related information about the DSL in a topology discovery table message to the B-RAS.

    The DSLAM sends topology discovery table data to the B-RAS in the following scenarios:

    • When the layer 2 control (L2C) session is up
    • When the line parameter changes are sensed or reported in the B-RAS by the DSLAM
    • When the DSL is down

    JunosE Software inserts topology discovery table data from the DSLAM into mirrored storage so that the data continues to be available even after SRP switchover. Therefore the subscriber is able to use the existing port data until the Access Node Control Protocol (ANCP) session is re-established and the DSLAM sends the updated data. When the updated port data is received from the DSLAM, corresponding entries are modified in the mirrored storage.

    To enable storage of topology discovery table data in mirrored storage:

    • Issue the persist-discovery-data enable command in L2C Configuration mode.
    host1(config-l2c)#persist-discovery-data enable

    Use the no version to disable storage of topology discovery table data in mirrored storage and completely clear existing data in mirrored storage.

    Published: 2014-08-12