42 and the neighboring device 2, and other stacked network switches 11 are now connected to the switch device 42 and the neighboring device 2 with the settings of LACP connections, and are connected to the last switch with the settings of LACP. Such configuration is referred to as the loop topology.

In some embodiments, after the operations of step 507 are completed, the to-be-tested stack 1 has been changed into the loop topology and is available to be subjected to a testing procedure to test routing efficiency associated with the L3 connection. It is noted that in this embodiment, the operations of step 507 are done with respect to settings of the L3 connection, while in other embodiments, the operations of step 507 are done with respect to settings of a layer 2 (L2) connection. In other embodiments, the computing device 41 may be configured such that a user is able to choose whether to test routing efficiency associated with the L2 connection prior to the steps of the method as shown in FIG. 2 being performed. It is noted that the testing procedure for testing the routing efficiency is well known in the related art, details thereof are omitted herein for the sake of brevity.

Then, in step 508, the computing device 41 deactivates the number (i) of network switches 11 that are activated in step 501. It is noted that in practice, the computing device 41 may transmit a deactivation signal to each of the (i) of network switches 11; alternatively, since the deactivated switch has already been deactivated, the computing device 41 may transmit the deactivation signal to each of the (i−1) of network switches 11 that are still activated and may not transmit the deactivation signal to the deactivated switch.

In step 509, the computing device 41 determines whether there is a network switch 11 that has not yet been activated. In a case where it is determined that there is a network switch 11 that has not yet been activated (meaning that the to-be-tested stack 1 includes at least one additional network switch 11 that can be added to the changed topology), the flow proceeds to step 510. Otherwise, in a case where it is determined that there is not a network switch 11 that has not yet been activated, the method is terminated.

In step 510, the computing device 41 adds one to the number (i), and activates the number (i) of network switches 11 included in the to-be-tested stack 1. In the embodiment of FIG. 2, (i) now equals 4, and the number (i) of network switches 11 include the last switch and the number (i−1) of network switches 11 that are arranged from the top of the column (i.e., the first (i−1) network switches 11 of the to-be-tested stack 1). In addition, connections between the network switches 11 that are established in the previous steps are disconnected, and the network switches 11 may be controlled to restart. The operations of step 510 may generally be implemented in a cases where the additional network switch 11 is present in the to-be-tested stack 1. Afterwards, the flow goes back to step 502. As such, the method may continue until it is determined that there is not a network switch 11 that has not yet been activated.

FIG. 4 is a block diagram of a system for automatically changing a topology of a plurality of network switches according to one embodiment of the disclosure. The system includes a to-be-tested stack 1′, a neighboring device 2, a switch device 42 and a computing device 41. It is noted that the combination of the to-be-tested stack 1′, the neighboring device 2 and the switch device 42 may be referred to as a topology structure.

In the embodiment of FIG. 4, the to-be-tested stack 1′ includes a number M of network switches 11′. In some embodiments, M is not smaller than 5. Each of the network switches 11′ may similarly be embodied using a network switch that supports multi-layer functionalities within the Ethernet, supports a number of routing protocols, and is said to be “stackable”. In the embodiment of FIG. 4, the network switches 11′ are said to be stacked in the following manner. The network switches 11′ are arranged in a top-down column with two adjacent network switches 11′ being physically connected to each other using a physical cable or a wire (i.e., stacking cables, indicated by the solid lines). One of the network switches 11′ that is placed on the top (i.e., at the start of the column) is also referred to as a master switch (U_first) that is used for communicating with the external environment, and one of the network switches 11′ that is placed on the bottom (i.e., at the end of the column) is also referred to as a last switch (U_last). One of the network switches 11′ that is neither the master switch nor the last switch may be assigned as a backup switch (U_backup) for the master switch, and each of the network switches 11′ that is neither the master switch nor the backup switch may be referred to as a slave switch. It is noted that four slave switches (including the last switch) are present in the embodiment of FIG. 4, while additional slave switches may be employed in other embodiments. Moreover, in other embodiments, another one of the network switches 11′ included in the to-be-tested stack 1′ may be assigned as the master switch, and yet another one of the network switches 11′ included in the to-be-tested stack 1′ may be assigned as the backup switch. That is to say, the assignment of the master switch and the backup switch is not limited to the configuration of FIG. 4.

In addition to the above connection, each of the network switches 11′ that is not the last switch is also directly connected to the last switch, and the one of the network switches 11′ that is arranged at the top of the column (i.e., the master switch, also referred to as a first switch) is connected to one of the network switches 11′ that is arranged at a third position counted from the bottom to the top of the column and that is labelled as (U_last-2), the connections being indicated by the broken lines. For the sake of simplified description, the one of the network switches 11′ that is arranged at the third position counted from the bottom to the top of the column and that is labelled as (U_last-2) is referred to as a third-to-last switch hereafter.

FIGS. 5A and 5B constitute a flow chart illustrating steps of an exemplary method for automatically switching a topology of a plurality of network switches according to one embodiment of the disclosure. In the embodiment of FIGS. 5A and 5B, the method is implemented using the system of FIG. 4. It is noted that the embodiment of FIGS. 5A and 5B illustrates the topology of the to-be-tested stack 1′ being changed from the point-to-point topology to the mesh topology.

In the embodiment of