+/**
+ * Get all the 802.1q VLAN configuration.
+ * Retrieves all the VLAN configuration in 802.1q mode.
+ * @note The switch should be in 802.1q mode.
+ * @note You must be logged on a switch.
+ * @param nga A pointer to the ngadmin structure.
+ * @param vlans A pointer to an array of unsigned shorts which will receive
+ * VLAN ids. Must not be NULL. \n
+ * The array size must be sizeof(unsigned short)*(*nb).
+ * @param ports A pointer to an array of unsigned chars which will receive the
+ 802.1q configuration for each VLAN. Must not be NULL. \n
+ The array size must be sizeof(unsigned char)*ports_count*(*nb).
+ * @param nb A pointer to an integer which contains the maximum number of
+ elements allowed in the array. Must not be NULL. \n
+ It will receive the actual number of VLAN written in the arrays.
+ * @return ERR_OK when everything is well or an error code otherwise.
+ **/