Learning a MAC address

1. A method for learning a Medium Access Control (MAC) address, applied in an edge device in an interconnection network of data centers, said method comprising:

based on a receipt of a request message from a first node to a second node, creating by the edge device a session cache item, wherein the session cache item includes: an Internet Protocol (IP) address of the second node, an IP address of the first node, and a first relationship between a MAC address of the first node and a first port of the edge device through which the request message was received;

based on a receipt of a response message from the second node to the first node, updating, by the edge device, the session cache item having the IP address of the first node and the IP address of the second node, wherein the updated session cache item further includes a second relationship between a MAC address of the second node and a second port of the edge device through which the response message was received; and

providing the first relationship and the second relationship to a data plane of the edge device to facilitate data packet forwarding between the first node and the second node.

2. The method of claim 1 , further comprising: forwarding, by the edge device, the response message to the first node via the first port indicated in the session cache item.

3. The method of claim 1 , wherein providing the first relationship and the second relationship to the data plane includes:

advertising a local MAC address in the session cache item through the first port in the session cache item;

receiving a remote MAC address advertised by another edge device; and

providing the first relationship and the second relationship to the data plane;

wherein one of the first relationship and the second relationship is between the local MAC address and first port in the session cache item, and the other relationship is between the received remote MAC address and a port through which the remote MAC address was received.

4. The method of claim 1 , wherein:

the first relationship is between a local MAC address and an output port corresponding to the local MAC address, in which the output port is a local port that the edge device accesses the local MAC address; and

the second relationship is between a remote MAC address and an output port corresponding to the remote MAC address, in which the output port is a port corresponding to a link between the edge device and a remote edge device.

5. The method of claim 1 , further comprising:

after the session cache item is created to include the first relationship, changing the session cache item to a first state indicating that a MAC address learning session is under establishment;

after the session cache item is updated with the second relationship, updating the session cache item from the first state to a second state indicating that the MAC address learning session has been established; and

wherein the first relationship and the second relationship are provided to the data plane of the edge device when the session cache item is in the second state.

6. The method of claim 5 , further comprising:

receiving a message broadcasted by a migrated node,

finding, in local session cache items, a session cache item containing an IP address of the migrated node, and

if the found session cache item is in the first state, updating the found session cache item according to a port through which the message from the migrated node was received, and if the found session cache item is in the second state, deleting the found session cache item if the migrated node is currently a local node of the edge device, and updating the found session cache item if the migrated node is currently a remote node of the edge device.

7. The method of claim 6 , wherein updating the found session cache item according to the port through which the message was received comprises:

if the found session cache item does not contain a MAC address of the migrated node, adding the MAC address of the migrated node and an output port corresponding to the MAC address of the migrated node in the found session cache item, and updating the session cache item to the second state; and

if the found session cache item contains the MAC address of the migrated node, updating the output port corresponding to the MAC address of the migrated node in the session cache item to the port through which the message was received.

8. The method of claim 6 , wherein the updating the session cache item if the migrated node is currently a remote node of the edge device comprises:

if an output port corresponding to a MAC address of the migrated node in the found session cache item is a local port, deleting the found session cache item; and

if the output port corresponding to the MAC address of the migrated node in the found session cache item is a port corresponding to a link between the edge device and a remote edge device, updating the output port corresponding to the MAC address of the migrated node in the session cache item to the port corresponding to the link receiving the message.

9. The method of claim 5 , further comprising:

when the session cache item is changed to the first state, starting a first timer of the session cache item to indicate that the session cache item is in the first state;

when the session cache item is updated from the first state to the second state, stopping the first timer, and starting a second timer of the session cache item to indicate that the session cache item is in the second state; and

if the first timer or the second timer expires, deleting the session cache item corresponding to the timer that expires, wherein an expiry time of the first timer is irrelevant to that of the second timer.

10. An edge device in an interconnection network of data centers, comprising:

a processor; and

a non-transitory computer readable medium storing instructions that when executed by the processor cause the processor to:

based on a receipt of a request message from a first node to a second node, create a session cache item, wherein the session cache item includes: an Internet Protocol (IP) address of the second node, an IP address of the first node, and a first relationship between a Medium Access Control (MAC) address of the first node and a first port of the edge device through which the request message was received;

based on a receipt of a response message from the second node to the first node, update the session cache item having the IP address of the first node and the IP address of the second node, wherein the updated session cache item further includes a second relationship between a MAC address of the second node and a second port of the edge device through which the response message was received; and

provide the first relationship and the second relationship to a data plane of the edge device to facilitate data packet forwarding between the first node and the second node.

11. The edge device of claim 10 , wherein the instructions are to cause the processor to forward the response message to the first node via the first port indicated in the session cache item.

12. The edge device of claim 10 , wherein when providing the first relationship and the second relationship to the data plane, the processor is further to:

advertise a local MAC address in the session cache item through a port corresponding to a remote MAC address in the session cache item;

receive a remote MAC address advertised by another edge device; and

provide the first relationship and the second relationship to the data plane, wherein the first relationship is between the local MAC address and an output port corresponding to the local MAC address in the session cache item, and the second relationship is between the received remote MAC address and a port through which the remote MAC address was received.

13. The edge device of claim 10 , wherein:

the first relationship is between a local MAC address and an output port corresponding to the local MAC address, in which the output port is a local port that the edge device accesses the local MAC address; and

the second relationship is between a remote MAC address and an output port corresponding to the remote MAC address, in which the output port is a port corresponding to a link between the edge device and a remote edge device.

14. The edge device of claim 10 , wherein the processor is further to:

after the session cache item is created to include the first relationship, change the session cache item to a first state indicating that a MAC address learning session is under establishment; and

after the session cache item is updated with the second relationship, update the session cache item from the first state to a second state indicating that the MAC address learning session has been established;

wherein the first relationship and the second relationship are provided to the data plane of the edge device when the session cache item is in the second state.

15. The edge device of claim 10 , wherein the processor is further to:

receive a message broadcasted by a migrated node,

find, in local session cache items, a session cache item containing an IP address of the migrated node, and

if the found session cache item is in the first state, update the found session cache item according to a port through which the message from the migrated node was received, and if the found session cache item is in the second state, delete the found session cache item if the migrated node is currently a local node of the edge device, and update the found session cache item if the migrated node is currently a remote node of the edge device.