ZDO_SrcRtgIndCB 怎么触发的

请问ZDO_SrcRtgIndCB这个函数，什么条件下会调用

参考工程内的说明可知该函数用于通知收到的ZDO可用的src路由记录。

/*********************************************************************
 * @fn          ZDO_SrcRtgIndCB
 *
 * @brief       This function notifies the ZDO available src route record received.
 *
 * @param       srcAddr - source address of the source route
 * @param       relayCnt - number of devices in the relay list
 * @param       relayList - relay list of the source route
 *
 * @return      none
 */
void ZDO_SrcRtgIndCB (uint16 srcAddr, uint8 relayCnt, uint16* pRelayList )
{
  zdoSrcRtg_t srcRtg;

  srcRtg.srcAddr = srcAddr;
  srcRtg.relayCnt = relayCnt;
  srcRtg.pRelayList = pRelayList;

  if( zdoCBFunc[ZDO_SRC_RTG_IND_CBID] != NULL )
  {
    zdoCBFunc[ZDO_SRC_RTG_IND_CBID]( (void*)&srcRtg );
  }
}

那调用ZDO_SrcRtgIndCB这个函数在哪呢？