Router and method for connecting an IPv4 network and an IPv6 network

1. A method performed by a router connected to an Internet Protocol Version 6 (IPv6) network and an Internet protocol Version 4 (IPv4) network, the method comprising:

receiving, from an IPv4 compliant device connected to the IPv4 network, a request for an IPv6 network resource enabled by an IPv6 compliant device connected to the IPv6 network;

obtaining from a first resource directory an external IPv4 address and an external IPv4 port number corresponding to the IPv6 network resource, the first resource directory comprising a name, a local IPv6 address, and a local IPv6 port, for the IPv6 network resource, the external IPv4 address, and the external IPv4 port number;

creating an entry in a network address translation table for enabling communication between the IPv4 compliant device and the IPv6 network resource, the entry comprising the external IPv4 address, the external IPv4 port number, the local IPv6 address and the local IPv6 port number for the IPv6 network resource, and a local IPv4 address and a local IPv4 port for the IPv4 compliant device; and

transmitting the external IPv4 address and the external IPv4 port number to the IPv4 compliant device.

2. The method of claim 1 , wherein the external IPv4 address is an IPv4 address of the router.

3. The method of claim 1 , wherein, before receiving the request for the IPv6 network resource, the method further comprises:

storing the external IPv4 address and the external IPv4 port number corresponding to the IPv6 network resource in the first resource directory.

4. The method of claim 1 , further comprising storing in the entry the local IPv4 address and the local IPv4 port number of the IPv4 compliant device.

5. The method of claim 1 , further comprising:

receiving, from the IPv4 compliant device, one or more packets destined to the external IPv4 address and the external IPv4 port; and

forwarding the one or more packets to the local IPv6 address and the local IPv6 port of the IPv6 network resource.

6. The method of claim 1 , wherein the method further comprises, before receiving the request for the IPv6 network resource:

receiving, from the IPv4 compliant device, a request to discover IPv6 network resources in the IPv6 network; and

transmitting information about at least one of the IPv6 network resources to the IPv4 compliant device.

7. The method of claim 1 , wherein the IPv6 network resource is indicated in a link format in the first resource directory.

8. The method of claim 1 , wherein the first resource directory has a first identifier, and the method further comprises transmitting the first identifier to the IPv4 compliant device.

9. The method of claim 8 , wherein the first identifier is transmitted to the IPv4 compliant device in a Hypertext Transfer Protocol, HTTP, message or a Constrained Application Protocol, CoAP, message.

10. A router for connecting an Internet Protocol Version 6 (IPv6) network and an Internet Protocol Version 4 (IPv4) network, the router comprising:

a processor; and

a memory storing instructions configured so that when executed on the processor, the instructions cause the router to:

receive, from an IPv4 compliant device connected to the IPv4 network, a request for an IPv6 network resource enabled by an IPv6 compliant device connected to the IPv6 network;

obtain from a first resource directory an external IPv4 address and an external IPv4 port number corresponding to the IPv6 network resource, the first resource directory comprising a name, a local IPv6 address, and a local IPv6 port, for the IPv6 network resource, the external IPv4 address, and the external IPv4 port number;

create an entry in a network address translation table for enabling communication between the IPv4 compliant device and the IPv6 network resource, the entry comprising the external IPv4 address, the external IPv4 port number, the local IPv6 address and the local IPv6 port number for the IPv6 network resource, and a local IPv4 address and a local IPv4 port for the IPv4 compliant device; and

transmit the external IPv4 address and the external IPv4 port number to the IPv4 compliant device.

11. The router of claim 10 , wherein the external IPv4 address is an IPv4 address of the router.

12. The router of claim 10 , wherein the instructions are further configured so as to cause the router to, before receiving the request for the IPv6 network resource, store the external IPv4 address and the external IPv4 port number corresponding to the IPv6 network resource in the first resource directory.

13. The router of claim 10 , wherein the instructions are further configured so as to cause the router to store in the entry the local IPv4 address and the local IPv4 port number of the IPv4 compliant device.

14. The router of claim 10 , wherein the instructions are further configured so as to cause the router to:

receive, from the IPv4 compliant device, one or more packets destined to the external IPv4 address and the external IPv4 port; and

forward the one or more packets to the local IPv6 address and the local IPv6 port of the IPv6 network resource.

15. The router of claim 10 , wherein the instructions are further configured so as to cause the router to, before receiving the request for the IPv6 network resource,

receive, from the IPv4 compliant device, a request to discover IPv6 network resources in the IPv6 network; and

transmit information about at least one of the IPv6 network resources to the IPv4 compliant device.

16. The router of claim 10 , wherein the IPv6 network resource is indicated in a link format in the first resource directory.

17. The router of claim 10 , wherein the first resource directory has a first identifier, and wherein the instructions are further configured so as to cause the router to transmit the first identifier to the IPv4 compliant device.

18. The router of claim 17 , wherein the first identifier is transmitted to the IPv4 compliant device in a Hypertext Transfer Protocol, HTTP, message or a Constrained Application Protocol, CoAP, message.

19. The router of claim 17 , wherein the first identifier is a part of the link format for the IPv6 network resource.

20. A non-transitory computer-readable medium comprising, stored thereupon, a computer program product comprising a computer program, wherein the computer program comprises instructions configured so that, when executed on a router connected to an Internet Protocol Version 6 (IPv6) network and an Internet protocol Version 4 (IPv4) network, the instructions configure the router to:

receive, from an IPv4 compliant device connected to the IPv4 network, a request for an IPv6 network resource enabled by an IPv6 compliant device connected to the IPv6 network;

obtain from a first resource directory an external IPv4 address and an external IPv4 port number corresponding to the IPv6 network resource, the first resource directory comprising a name, a local IPv6 address, and a local IPv6 port, for the IPv6 network resource, the external IPv4 address, and the external IPv4 port number;

create an entry in a network address translation table for enabling communication between the IPv4 compliant device and the IPv6 network resource, the entry comprising the external IPv4 address, the external IPv4 port number, the local IPv6 address and the local IPv6 port number for the IPv6 network resource, and a local IPv4 address and a local IPv4 port for the IPv4 compliant device; and

transmit the external IPv4 address and the external IPv4 port number to the IPv4 compliant device.