The invention relates to method for determining a virtual machine migration. The Examining Division refused the application, as it considered no objective technical problem was credibly solved.
The Board agreed with the Appellant and considered that at least one of the distinguishing features provided the effect that a unique identifier of a virtual machine is obtained efficiently. Since the skilled person had no hint, or without hindsight would not obtain the unique identifier as claimed, the subject matter of the claim involves an inventive step
Here are the practical takeaways from the decision T 1573/21 (DETERMINING VIRTUAL MACHINE DRIFTING / Huawei) of August 30, 2023, of the Technical Board of Appeal 3.5.05.
Key takeaways
The invention
The invention was defined by the Board as follows:
The current application pertains to a method for determining a virtual machine migration. On a host machine, a client component obtains a unique identifier of a virtual machine from an Address Resolution Protocol, ARP, packet from the virtual machine. The client component determines if this identifier exists in a local record stored on the host machine. If the identifier does not exist in the local record, it is added to the record and sent to a server in a packet, together with the address of the host machine. This packet enables the server to determine if the virtual machine was migrated: this is the case if the identifier exists in a record on the server, but is associated with the address of a different host machine.

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Method Claim 1
Is it patentable?
In the decision under appeal, the Examining Division considered there were distinguishing features, as follows:
3.2 According to the decision under appeal, D1 did not disclose the following two features of claim 1:
(a) the server determines that the virtual machine is migrated when the unique identifier of the virtual machine exists in a record of the server and the address of the host machine carried in the packet is different from a host machine address corresponding to the unique identifier of the virtual machine in the record of the server
(b) the unique identifier of the virtual machine is obtained by either intercepting or receiving an Address Resolution Protocol, ARP, packet carrying the unique identifier of the virtual machine from the virtual machine on the host machine.
However, the Division considered that no technical problem was solved by the invention, and thus was not inventive.
3.4 The examining division argued that no objective technical problem was credibly solved over the scope of claim 1 and made a reference to a “case when a virtual machine which was previously located on the client is again migrated back to that client, this client won’t send a packet to the server since the local record is still present as it doesn’t get deleted when a virtual machine is migrated to another server. Therefore, the correct detection of a migration is not consistently achieved and thus a proper definition of a technical effect (which goes beyond the well-known technical effects of data exchange in a network) provided by the differing features is not possible”.
The board notes that this objection in the decision under appeal relates to distinguishing feature (a) only. It is not necessary to take a position on it because distinguishing feature (b) establishes an inventive step, as explained below.
3.5 The technical effect caused by feature (b) is that a unique identifier of a virtual machine is obtained efficiently (see paragraph 62 of the description of the application in suit).
3.6 The objective technical problem to be solved is accordingly “how to efficiently obtain a unique identifier of a virtual machine“.
Based on the above analysis, the Board assessed if it was obvious to the skilled person:
3.7 Faced with this problem, the skilled person would not receive any hint from document D1 to intercept or receive an ARP packet and to obtain a unique identifier from the packet. Firstly, D1 discloses in paragraph 123 that an identifier of a new virtual machine is sent to a firewall coordinator, but does not specify how such identifier is to be obtained.
Secondly, ARP packets, as such, are generally known. However, it is not apparent how a skilled person, without resorting to hindsight, would specifically select an ARP packet as a source for a unique identifier of a virtual machine.
Therefore, the Board found the subject-matter of the claim involves an inventive step.
More information
You can read the full decision here: T 1573/21 (DETERMINING VIRTUAL MACHINE DRIFTING / Huawei) of August 30, 2023, of the Technical Board of Appeal 3.5.05.