# US 10,771,431 B2 · Synchronizing IP information of virtual machines

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- Number: US 10,771,431 B2
- Document ID: US10771431B2
- Status: Granted
- Kind: B2
- Application number: 14/216,631
- Filed: 2014-03-17
- Published: 2014-10-02
- Granted: 2020-09-08
- Earliest claimed: 2013-03-27
- Assignees: Lenovo Enterprise Solutions (Singapore) Pte. Ltd.
- Applicants: Lenovo Enterprise Solutions (Singapore) Pte. Ltd.
- Inventors: Xiang H. Dong; Shi X. Ruan; Yun Sun; Zheng D. Zhu
- Web page: https://patentgrep.com/patent/US10771431B2

## CPC

- H04L 61/5076: Update or notification mechanisms, e.g. DynDNS
- G06F 9/45533: {Hypervisors; Virtual machine monitors}
- G06F 9/45558: {Hypervisor-specific management and integration aspects}
- H04L 61/103: across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]
- G06F 2009/45595: {Network integration; Enabling network access in virtual machine instances}
- H04L 61/5014: using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

One embodiment discloses a method and apparatus for synchronizing IP information of virtual machines. The method includes: obtaining an IP relevant message of at least one virtual machine within a subnet, recording IP information and connection information of the at least one virtual machine based on the IP relevant message, and modifying connection information of a specific virtual machine in response to migration of the specific virtual machine. The apparatus corresponds to the method. With the method and apparatus above, IP information and connection information of respective virtual machines within the subnet are recorded regularly and routinely. Once a certain virtual machine is migrated, updating and modifying connection information of the migrated virtual machine is only needed, but without a need for resending a request to the Dynamic Host Configuration Protocol (DHCP) server. Thus, network disruptions caused by non-synchronization of IP information when the virtual machine is migrated are avoided.

## Claims

### Claim 1

A method for synchronizing internet protocol (IP) information of virtual machines in a switch, the method comprising:
prior to a migration of a virtual machine within a subnet:
obtaining, by a switch, an IP relevant message of the virtual machine within the subnet by snooping a transmission of another device in the subnet;
recording, by the switch, IP information and connection information of the virtual machine based on the IP relevant message; and
in response to migration of the virtual machine, modifying, by the switch, connection information of the virtual machine while maintaining the IP information of the virtual machine through migration.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the IP relevant message comprises the IP confirmation message of the at least one virtual machine, and wherein the transmission is the broadcast message from the DHCP server.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the IP relevant message comprises the IP confirmation message of a virtual machine of the at least one virtual machine hosted by the server that is connected to the switch, and wherein the transmission is the unicast message from the DHCP server.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the IP relevant message comprises the IP confirmation message of a second virtual machine of the at least one virtual machine that is hosted by another server that is connected to another switch in the subnet, and wherein the IP confirmation message is obtained by snooping a broadcast from the another switch in the subnet.

### Claim 5 (depends on 4)

The method according to claim 4, wherein the connection information comprises:
connection status information; and
a lease time corresponding to the IP information, and wherein recording the IP information and the connection information of the at least one virtual machine comprises:
recording the connection status information of a first virtual machine of the at least one virtual machine that is connected to the switch as a first status;
recording the connection status information of the second virtual machine of the at least one virtual machine that is connected to another switch as a second status; and
deleting IP information for a third virtual machine in response to a lease time corresponding to the IP information for the third virtual machine having expired.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the specific virtual machine is migrated in from another switch or migrated out from the switch, and wherein the switch modifying the connection information of the specific virtual machine comprises:
modifying the connection status information of the specific virtual machine from the second status into the first status and recording determined connection parameter information of the specific virtual machine in response to the specific virtual machine migrating in from another switch; and
modifying the connection status information of the specific virtual machine from the first status into the second status in response to the specific virtual machine migrating out from the switch.

### Claim 7 (depends on 1)

The method according to claim 1, further comprising the switch maintaining a record table that stores the IP information and the connection information of virtual machines in the subnet, the record table comprising a plurality of entries, each entry storing information for a specific virtual machine including:
a media access control (MAC) address;
an IP address;
a port;
a virtual local area network (VLAN);
a lease time; and
connection status information indicating an active connection or an inactive connection.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the switch obtaining the IP relevant message of the at least one virtual machine within the subnet comprises obtaining an IP release message of a certain virtual machine of the at least one virtual machine, and
wherein the switch recording the IP information and connection information of the at least one virtual machine comprises deleting IP information of the certain virtual machine.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the IP relevant message is a unicasted DHCP ACK packet, and wherein the switch broadcasting the IP confirmation message within the subnet more than one time comprises, prior to broadcasting the IP confirmation message:
the switch modifying a target media access control (MAC) address of the DHCP ACK packet as FF:FF:FF:FF:FF:FF;
the switch modifying a target IP address as 255.255.255.255;
the switch recalculating an IP head checksum; and
the switch maintaining other fields of the DHCP ACK packet.

### Claim 10

An apparatus for synchronizing internet protocol (IP) information of virtual machines in a switch, the apparatus comprising at least one hardware processor and logic integrated with and/or executable by the at least one hardware processor, the logic being configured as:
a message obtaining unit configured to obtain, prior to a migration of a virtual machine within a subnet, an IP relevant message of the virtual machine within the subnet by snooping a transmission of another device in the subnet;
a recording unit configured to record, prior to the migration of the virtual machine within the subnet, IP information and connection information of the virtual machine based on the IP relevant message; and
a modifying unit configured to modify, in response to migration of the virtual machine, connection information of the virtual machine while maintaining the IP information of the virtual machine through migration.

### Claim 11 (depends on 10)

The apparatus according to claim 10, wherein the IP relevant message comprises the IP confirmation message of the at least one virtual machine, and wherein the transmission is the broadcast message from the DHCP server.

### Claim 12 (depends on 10)

The apparatus according to claim 10, wherein the IP relevant message comprises the IP confirmation message of a virtual machine of the at least one virtual machine that is connected to the switch, wherein the transmission is the unicast message from the DHCP server, wherein the IP relevant message further comprises a unicasted DHCP ACK packet, and wherein the message obtaining unit is further configured to, prior to broadcasting the IP confirmation message:
modify a target media access control (MAC) address of the DHCP ACK packet as FF:FF:FF:FF:FF:FF;
modify a target IP address as 255.255.255.255;
recalculate an IP head checksum; and
maintain other fields of the DHCP ACK packet.

### Claim 13 (depends on 10)

The apparatus according to claim 10, wherein the IP relevant message comprises the IP confirmation message of a second virtual machine of the at least one virtual machine that is hosted by another server that is connected to another switch in the subnet, and wherein the message obtaining unit is configured to obtain the IP confirmation message by snooping a broadcast from the another switch in the subnet.

### Claim 14 (depends on 13)

The apparatus according to claim 13, wherein the connection information comprises connection status information, and wherein the recording unit is configured to:
record the connection status information of a first virtual machine of the at least one virtual machine that is connected to the switch as a first status; and
record the connection status information of the second virtual machine of the at least one virtual machine that is connected to another switch as a second status.

### Claim 15 (depends on 14)

The apparatus according to claim 14, wherein the modifying unit is configured to modify the connection status information of the specific virtual machine from the second status into the first status and record determined connection parameter information of the specific virtual machine in response to that the specific virtual machine being migrated in from another switch.

### Claim 16 (depends on 14)

The apparatus according to claim 14, wherein the modifying unit is configured to modify the connection status information of the specific virtual machine from the first status into the second status in response to the specific virtual machine being migrated out from the switch.

### Claim 17 (depends on 10)

The apparatus according to claim 10, wherein the message obtaining unit is configured to obtain an IP release message of a certain virtual machine of the at least one virtual machine, wherein the recording unit is configured to delete IP information of the certain virtual machine, and wherein the recording unit is configured to maintain a record table that stores the IP information and the connection information of virtual machines in the subnet, the record table comprising a plurality of entries, each entry storing information for a specific virtual machine including:
a media access control (MAC) address;
an IP address;
a port;
a virtual local area network (VLAN);
a lease time; and
connection status information indicating an active connection or an inactive connection.

### Claim 18 (depends on 10)

The apparatus according to claim 10, wherein the modifying unit is configured to modify a connection parameter of the specific virtual machine in response to the specific virtual machine being migrated within the switch.

### Claim 19

A computer program product, comprising a non-transitory computer readable storage medium having program instructions embodied therewith, the embodied program instructions readable/executable by a processor to cause the processor to perform a method comprising:
prior to a migration of a virtual machine within a subnet:
obtaining an IP relevant message of the virtual machine within the subnet by snooping a transmission of another device in the subnet;
recording IP information and connection information of the virtual machine based on the IP relevant message; and
modifying connection information of the virtual machine in response to migration of the virtual machine, while maintaining the IP information of the virtual machine through migration.

### Claim 20 (depends on 19)

The computer program product as recited in claim 19, wherein the embodied program instructions are configured to snoop the IP relevant message of the at least one virtual machine within the subnet from the transmission selected from a group consisting of: the broadcast message from the DHCP server, the unicast message from the DHCP server, the IP confirmation message of a second virtual machine of the at least one virtual machine that is connected to another switch in the subnet, and the IP release message of the certain virtual machine of the at least one virtual machine, wherein the IP relevant message is a unicasted DHCP ACK packet that comprises the IP confirmation message of the at least one virtual machine, and wherein the method comprises, prior to broadcasting the IP confirmation message:
modifying a target media access control (MAC) address of the DHCP ACK packet as FF:FF:FF:FF:FF:FF;
modifying a target IP address as 255.255.255.255;
recalculating an IP head checksum; and
maintaining other fields of the DHCP ACK packet.