CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Entry of PCT/JP2019/008855 filed on Mar. 6, 2019, which claims priority from Japanese Patent Application 2018-041047 filed on Mar. 7, 2018, the contents of all of which are incorporated herein by reference, in their entirety. The present invention relates to a terminal apparatus, a switch, a network system, a test method and a program.

BACKGROUND

Field

In recent years the demand for ensuring reliability of network is increasing, and it is an urgent issue to promptly identify a fault location when a certain path failure has occurred. In order to ensure reliability, means by which a path is configured in a redundant manner may be used. As a method, a link aggregation function (LAG function: IEEE 802.3ad) may be enumerated in a case of an Ethernet (registered trademark) network. This LAG function is a function of ensuring a path redundancy and improving reliability by regarding a plurality of physically connected lines (links) as logically one line (link). This LAG function is also referred to as a port trunking function.

In a network for which reliability is demanded, a network management system is often introduced which allows monitoring failure information of individual apparatuses (for example, an Ethernet (registered trademark) switch or the like) in the network and manage a fault location. However, individual apparatuses in a network often cannot autonomically detect a failure occurring in it. As a method of confirming normality of the network in such a case, use may be made of a method of confirming whether or not a packet arrives, by software called ping. Confirmation by ping confirms normality in a network by confirming whether or not a packet arrives between terminals ending with an IP (Internet Protocol).

However, this ping issues an IP packet to a terminal etc. and confirms communication based on a response thereof but cannot directly designate an intermediate physical path in a LAG. Accordingly, in a network in which path redundancy is ensured by LAG or the like, it is difficult to grasp a state of a physical line (link) only with ping. For example, if a packet by ping did not arrive, it is difficult to identify a section where an abnormality has occurred.

Patent Literature (PTL) 1 discloses a frame transmission apparatus in a communication apparatus in which a plurality of physical ports are bundled into a logical port, wherein the frame transmission apparatus supports overall confirmation of normality of a plurality of frame transfer paths within the apparatus. The frame transmission apparatus disclosed in this literature is provided with a plurality of ports possessed by a line unit and a setting control unit. This setting control unit confirms normality of a frame transfer state within the apparatus, by transferring a maintenance frame from a first port to a second port in the apparatus. If the first port is a logical port in which a plurality of physical ports are link-aggregated, this setting control unit selects each of the plurality of physical ports as a transmission source port, and transfers a plurality of maintenance frames from a plurality of physical ports to the second port.

Patent Literature 2 discloses a detection apparatus that can achieve improvement in accuracy of detection of a section in which a failure has occurred in a network. According to this literature, the detection apparatus transmits to a storage apparatus a packet group for quality analysis including unique transmission source MAC addresses of the maximum number of links among the number of links of individual sections in a path that is a target for detection of a failure occurrence section, in accordance with a prescribed distribution rule. Next, the detection apparatus identifies, from the result transmitted, a combination of transmission source MAC addresses for which packet loss has actually occurred. Next, in a case where the quality analysis packet group is distributed to individual links in individual sections in accordance with a prescribed distribution rule, the detection apparatus identifies a group of transmission source MAC addresses in the quality analysis packets distributed to the individual links. The detection apparatus detects a failure occurrence section from a group of transmission source MAC addresses corresponding to the combination of transmission source MAC addresses where packet loss has actually occurred.

[PTL 1] Japanese Patent Kokai Publication No. 2015-2413A

[PTL 2] Japanese Patent Kokai Publication No. 2013-157957A

SUMMARY

The following analysis is given according to the present invention. The method of Patent Literature 1, however, only assumes a case where a trunk is configured for both transmission source and transmission destination of LBM.

In the method of Patent Literature 2 it is possible to detect in which section of LAG configured in a multi-stage manner a failure has occurred, but there is a problem in that it is not possible to identify in which physical link thereof the failure has occurred.

It is an object of the present invention to provide a terminal apparatus, a switch, a network system, a test method and a program that can contribute to improving efficiency of testing a logical link configured in multiple stages by using link aggregating technology as represented by link aggregation.

According to a first aspect, provided is a terminal apparatus comprising: an inspection execution part that executes an inspection by transmitting a test packet to a prescribed destination apparatus reached via a plurality of logical links, the logical link being configured by a switch having a function of aggregating a plurality of physical links between the switch and an adjacent switch to use the physical links as a logical link; and a test packet creation part that creates, based on a rule of selecting a physical link as a component of the logical link by the switch, a plurality of kinds of test packets for which a transmission source address(es) of the test packet(s) is(are) so rewritten to enable confirmation of normality of the plurality of physical links between the terminal apparatus and the prescribed destination apparatus.

According to a second aspect, provided is a switch having a function of aggregating a plurality of physical links between the switch and an adjacent switch to use the physical links as a logical link, wherein the switch selects the physical link by using a rule of selecting the physical link based on a transmission source address of a prescribed test packet and switch-unique information, and transfers the test packet.

According to a third aspect, provided is a network system including the abovementioned terminal apparatus and switch.

According to a fourth aspect, provided is a test method, wherein a terminal apparatus comprising an inspection execution part that executes an inspection by transmitting a test packet to a prescribed destination apparatus reached via a plurality of logical links, the logical link being configured by a switch having a function of aggregating a plurality of physical links between the switch and an adjacent switch to use the physical links as a logical link repeats a step of creating, based on a rule of selecting a physical link as a component of the logical link by the switch, a test packet for which a transmission source address of the test packet is so rewritten to enable confirmation of normality of the plurality of physical links between the terminal apparatus and the prescribed destination apparatus, and a step of transmitting the test packet, to confirm normality of the plurality of physical links between the terminal apparatus and the prescribed destination apparatus. This method is associated with a particular mechanism, which is a terminal apparatus that transmits the abovementioned test packet.

According to a fifth aspect, provided is a program for realizing the functionality of the abovementioned terminal apparatus, or a program for implementing the test method indicated in the abovementioned fourth aspect. It is to be noted that this program may be implemented by a computer having a memory and may be recorded (stored) on a computer-readable (non-transient) storage medium. That is, the present invention may be embodied as a computer program product.

According to the present disclosure, it is possible to improve efficiency in testing of a logical link configured in multiple stages by using link aggregating technology as represented by link aggregation.

