Methods and switch devices for switching data frames in a communications network

1 . A method performed by a source switch device, for switching data frames in a communications network comprising a plurality of switch devices including the source switch device, wherein the source switch device is provided with a switch identifier (switch ID) and wherein each port of the source switch device is provided with a port number, and said each port of the source switch device is associated with a virtual local area network identifier (VLAN ID), the method comprising:

receiving a data frame from a source host node that is connected to the source switch device, wherein the data frame includes a source Media Access Control (MAC) address of the source host node, and a source Internet Protocol (IP) address of the source host node;

modifying the data frame by replacing the source MAC address of the received data frame with information comprising: the switch ID, a VLAN ID associated with a port of the source switch device from which port the data frame is received, and the source IP address;

determining that there is a MAC address table in the source switch device;

in response to determining that there is a MAC address table in the source switch device, and

in response to determining that the MAC address table in the source switch device does not include an entry comprising the source IP address and the source MAC address,

including in the entry of the MAC address table, the source IP address, the source MAC address, a port number indicating the port of the source switch device from which port the data frame is received, and the VLAN ID associated with the port of the source switch device from which port the data frame is received;

in response to determining that there is no MAC address table in the source switch device,

generating a MAC address table and including in an entry of the generated MAC address table, the source IP address, the source MAC address, a port number indicating the port of the source switch device from which port the data frame is received, and the VLAN ID associated with the port of the source switch device from which port the data frame is received; and

forwarding or flooding the modified data frame to at least one switch device of the plurality of switch devices.

2 . The method according to claim 1 , wherein at least 12 bits of a source MAC address field of the received data frame are configured for the VLAN ID.

3 . The method according to claim 1 , wherein a switch ID is obtained for said each of the plurality of switch devices.

4 . The method according to claim 1 , wherein the data frame includes a sender MAC address, and the method comprises replacing the sender MAC address of the received data frame with information comprising: the switch ID, the VLAN ID associated with the port of the source switch device from which port the data frame is received, and the source IP address.

5 . The method according to claim 1 , if the received data frame is a unicast message or an Address Resolution Protocol (ARP) reply message, the method further comprising fetching a switch ID from a destination MAC address field of the received data frame, and determining an entry of a switch table of the source switch device, where the fetched switch ID from the destination MAC address field of the received data frame is associated with a port number in the entry of the switch table, and forwarding the received data frame through a port indicated by the port number to another switch device of the plurality of switch devices.

6 . The method according to claim 1 , wherein the modified data frame is a modified broadcast frame or a modified broadcast message.

7 . The method according to claim 1 , wherein each port of a switch device of the plurality of switch devices is provided with a port number, and said each port of the switch device of the plurality of switch devices is associated with a VLAN ID.

8 . The method according to claim 7 , wherein the modified data frame is configured to pass through a port of the switch device of the plurality of switch devices if a VLAN ID associated with the port of the switch device is equal to 0, or if the modified data frame has a same VLAN ID as that associated with the port of the switch device.

9 . A source switch device for switching data frames in a communications network comprising a plurality of switch devices including the source switch device, wherein the source switch device is provided with a switch identifier (switch ID), and wherein each port of the source switch device is provided with a port number, and said each port of the source switch device is associated with a virtual local area network identifier (VLAN ID), the source switch device comprising a processor and a memory, the memory containing instructions executable by the processor, whereby the source switch device is operative to:

receive a data frame from a source host node that is connected to the source switch device, wherein the data frame includes a source Media Access Control (MAC) address of the source host node, and a source Internet Protocol (IP) address of the source host node;

modify the data frame by replacing the source MAC address of the received data frame with information comprising: the switch ID, a VLAN ID associated with a port of the source switch device from which port the data frame is received, and the source IP address;

determine if there is a MAC address table in the source switch device;

if determine that there is the MAC address table in the source switch device, and if the MAC address table in the source switch device does not include an entry comprising the source IP address and the source MAC address,

include in the entry of the MAC address table, the source IP address, the source MAC address, a port number indicating the port of the source switch device from which port the data frame is received, and the VLAN ID associated with the port of the source switch device from which port the data frame is received;

if determine that there is no MAC address table in the source switch device,

generate a MAC address table and include in an entry of the generated MAC address table, the source IP address, the source MAC address, the port number indicating the port of the source switch device from which port the data frame is received, and the VLAN ID associated with the port of the source switch device from which port the data frame is received; and

forward or flood the modified data frame to at least one switch device of the plurality of switch devices.

10 . The source switch device according to claim 9 , wherein at least 12 bits of a source MAC address field of the received data frame are configured for the VLAN ID.

11 . The source switch device according to claim 9 , wherein a switch ID is obtained for each of the plurality of switch devices.

12 . The source switch device according to claim 9 , wherein the data frame includes a sender MAC address, and the source switch device is operative to replace the sender MAC address of the received data frame with information comprising: the switch ID, the VLAN ID associated with the port of the source switch device from which port the data frame is received, and the source IP address.

13 . The source switch device according to claim 9 , if the received data frame is a unicast message or an Address Resolution Protocol (ARP) reply message, the source switch device is further operative to fetch a switch ID from a destination MAC address field of the received data frame, and determine an entry of a switch table of the source switch device, where the fetched switch ID from the destination MAC address field of the received data frame is associated with a port number in the entry of the switch table, and forward the received data frame through a port indicated by the port number to another switch device of the plurality of switch devices.

14 . The source switch device according to claim 9 , wherein each port of a switch device of the plurality of switch devices is provided with a port number, and said each port of the switch device of the plurality of switch devices is associated with a VLAN ID.

15 . The source switch device according to claim 14 , wherein the modified data frame is configured to pass through a port of the switch device of the plurality of switch devices if a VLAN ID associated with the port of the switch device is equal to 0, or if the modified data frame has a same VLAN ID as that associated with the port of the switch device.

16 . A transit switch device for switching data frames in a communications network comprising a plurality of switch devices including the transit switch device, the transit switch device comprising a processor and a memory, the memory containing instructions executable by the processor, whereby the transit switch device is operative to:

receive a modified data frame from a source switch device, wherein the modified data frame is modified from a data frame including a source Media Access Control (MAC) address of a source host node, and a source Internet Protocol (IP) address of the source host node, by replacing the source MAC address of the data frame with information comprising: a switch ID of the source switch device, a VLAN ID associated with a port of the source switch device from which port the data frame is received, and a source IP address of the source host node;

fetch from a source MAC address field of the received modified data frame, the switch ID of the source switch device;

determine if there is a switch table in the transit switch device;

if determine that there is no switch table in the transit switch device,

generate a switch table, and including in an entry of the generated switch table, the fetched switch ID and a port number indicating a port of the transit switch device from which port the modified data frame is received;

if determine that there is a switch table in the transit switch device, and if the switch table in the transit switch device does not include an entry comprising the fetched switch ID and the port number indicating the port of the transit switch device from which port the modified data frame is received,

include in the entry of the switch table, the fetched switch ID and the port number indicating the port of the transit switch device from which port the modified data frame is received; and

forward or flood the modified data frame to at least one switch device of the plurality of switch devices.

17 . The transit switch device according to claim 16 , if the modified data frame is a unicast message or an ARP reply message, the transit switch device is further operative to fetch a switch ID from a destination MAC address field of the modified data frame, and determine an entry of a switch table of the transit switch device, where the fetched switch ID from the destination MAC address field of the modified data frame is associated with a port number in the entry of the switch table, and forward the modified data frame through a port indicated by the port number to another switch device of the plurality of switch devices.

18 . A destination switch device, for switching data frames in a communications network comprising a plurality of switch devices including the destination switch device, the destination switch device comprising a processor and a memory, the memory containing instructions executable by the processor whereby the destination switch device is operative to:

receive a modified data frame from a transit switch device, wherein the modified data frame is modified from a data frame including a source Media Access Control (MAC) address of a source host node, and a source Internet Protocol (IP) address of the source host node, by replacing the source MAC address of the data frame with information comprising: a switch ID of a source switch device, a VLAN ID associated with a port of the source switch device from which port the data frame is received, and a source IP address of the source host node;

fetch from a source MAC address field of the received modified data frame, the switch ID;

determine if there is a switch table in the destination switch device;

if determine that there is no switch table in the destinations witch device,

generate a switch table, and including in an entry of the generated switch table, the fetched switch ID and a port number indicating a port of the destination switch device from which port the modified data frame is received;

if determine that there is a switch table in the destination switch device, and if the switch table in the destination switch device does not include an entry comprising the fetched switch ID and the port number indicating the port of the destination switch device from which port the modified data frame is received,

include in the entry of the switch table, the fetched switch ID and the port number indicating the port of the destination switch device from which port the modified data frame is received; and

forward or flood the received modified data frame to at least a destination host node that is connected to the destination switch device.

19 . The destination switch device according to claim 18 , if the modified data frame is a unicast message or an ARP reply message, the destination switch device is further operative to fetch a switch ID from a destination MAC address field of the modified data frame, and determine an entry of a switch table of the destination switch device, wherein the fetched switch ID from the destination MAC address field of the modified data frame is associated with a port number in the entry of the switch table, wherein the fetched switch ID from the destination MAC address field of the modified data frame is the same as a switch ID of the destination switch device, and the destination switch device is further operative to forward the modified data frame through a port indicated by the port number to the destination host node.