Apparatus and methods for handling name resolution over IPV6 using NAT-PT and DNS-ALG

• US 7,864,780 B1
• Filed: 04/29/2003
• Issued: 01/04/2011
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Satapati, Suresh
• Primary Examiner(s): Mills; Donald L
• Assistant Examiner(s): Baron; Henry
• Application Number:
  US10/427,206
• Time in Patent Office: 2,807 Days
• Field of Search: 370/392, 370/466, 370/401, 370/252, 370/389, 370/236, 455/432
• US Class Current: 370/395.54
• CPC Class Codes: H04L 61/251 between different IP versions
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/167 Adaptation for transition between two IP versions, e.g. between IPv4 and IPv6 translation of Internet protocol [IP] addresses H04L61/2503

Abstract

Methods and apparatus for processing a DNS query by a NAT device are disclosed. A NAT device (e.g., NAT-PT device) receives the DNS query from a node. The NAT device then sends two DNS queries to a DNS server. Specifically, each of the DNS queries requests an IP address in a different version of IP (e.g., IPv4 or IPv6). For example, each of the DNS queries may request an A record or an AAAA record. When the NAT device receives two DNS replies from the DNS server, it forwards only one of the DNS replies to the node. Specifically, the DNS reply that is forwarded includes at least one answer record. DNS replies that do not include at least one answer record, or are received subsequent to forwarding the DNS reply to the node, are dropped by the NAT device.

Claims

1. A method, comprising:

receiving by a device adapted for performing Network Address Translation and Protocol Translation a single DNS query from a node, the single DNS query requesting an IP address for a name;

automatically sending by the device two DNS queries to a DNS server in response to the single DNS query received from the node, the two DNS queries including a first DNS query that includes the name and a second DNS query that includes the name, the two DNS queries conforming to two different IP protocols, wherein the node is in a domain conforming to a first one of the two different IP protocols and the DNS server is in a domain conforming to a second one of the two different IP protocols;

receiving by the device a first DNS reply from the DNS server;

receiving by the device a second DNS reply from the DNS server, the second DNS reply being received subsequent to the first DNS reply; and

when the first DNS reply includes at least one answer resource record, automatically forwarding the first DNS reply to the node and dropping the second DNS reply, wherein forwarding the first DNS reply is performed without waiting for the second DNS reply to be received;

wherein sending the second DNS query is performed automatically without waiting for a DNS reply corresponding to the first DNS query to be received.

2. The method as recited in claim 1, wherein the DNS server is in an IPv4 domain and the node is in an IPv6 domain.

3. The method as recited in claim 1, further comprising:

performing protocol translation on an IP header of the first DNS reply prior to forwarding the first DNS reply to the node.

4. The method as recited in claim 1, further comprising:

performing network address translation on an IP header of the first DNS reply prior to forwarding the first DNS reply to the node.

5. The method as recited in claim 1, further comprising:

performing protocol translation on a destination IP address of the first DNS reply prior to forwarding the first DNS reply to the node.

6. The method as recited in claim 5, wherein performing protocol translation comprises:

converting the destination and source IP address from an IPv4 address to an IPv6 address.

7. The method as recited in claim 5, wherein performing protocol translation comprises:

converting the destination and source IP address from a 32 bit address to a 128 bit address.

8. The method as recited in claim 5, wherein performing protocol translation comprises:

converting the destination and source IP address from an IPv6 address to an IPv4 address.

9. The method as recited in claim 5, wherein performing protocol translation comprises:

converting the destination and source IP address from a 128 bit address to a 32 bit address.

10. The method as recited in claim 5, further comprising:

performing network address translation on the destination IP address prior to forwarding the first DNS reply to the node.

11. The method as recited in claim 1, further comprising:

performing protocol translation on an address provided in a payload of the first DNS reply prior to forwarding the first DNS reply to the node.

12. The method as recited in claim 11, further comprising:

modifying a type provided in a payload of the first DNS reply prior to forwarding the first DNS reply to the node.

13. The method as recited in claim 12, wherein modifying the type comprises changing the type from A to AAAA.

14. The method as recited in claim 12, wherein modifying the type comprises changing the type from AAAA to A.

15. The method as recited in claim 1, further comprising:

performing protocol translation on a destination IP address provided in an IP header of at least one of the two DNS queries prior to sending the two DNS queries to the DNS server.

16. The method as recited in claim 15, further comprising:

performing network address translation on the destination IP address provided in the IP header of at least one of the two DNS queries prior to sending the two DNS queries to the DNS server.

17. The method as recited in claim 1, further comprising:

performing protocol translation on one or more IP addresses provided in an IP header of at least one of the two DNS queries prior to sending the two DNS queries to the DNS server.

18. The method as recited in claim 1, further comprising:

performing network address translation on one or more IP addresses in an IP header of at least one of the two DNS queries prior to sending the two DNS queries to the DNS server.

19. The method as recited in claim 1, wherein sending two DNS queries comprises:

generating a second DNS query from the single DNS query received from the node, each of the DNS queries requesting an IPv4 address or an IPv6 address.

20. The method as recited in claim 1, wherein each of the DNS replies is an A record or an AAAA record.

23. The method as recited in claim 1, further comprising:

determining whether the first DNS reply includes at least one answer resource record;

wherein forwarding the first DNS reply is performed when the first DNS reply includes at least one answer resource record;

wherein dropping the second DNS reply is performed without determining whether the second DNS reply includes at least one answer resource record.

24. The method as recited in claim 1, wherein forwarding the first DNS reply is performed independent of the protocol of each of the DNS replies.

26. The method as recited in claim 1, wherein forwarding the first DNS reply is performed prior to receiving the second DNS reply.

27. The method as recited in claim 1, wherein sending two DNS queries comprises:

generating a second DNS query from the DNS query received from the node, the two DNS queries including a request for an IPv4 address and a request for an IPv6 address.

28. The method as recited in claim 1, wherein sending two DNS queries comprises:

generating a second DNS query from the single DNS query received from the node.

29. The method as recited in claim 1, further comprising:

when the first DNS reply does not include at least one answer resource record, forwarding the second DNS reply to the node and dropping the first DNS reply.

21. A computer-readable storage medium storing thereon computer-readable instructions, comprising:

instructions for processing a single DNS query after receiving the single DNS query from a node, the single DNS query requesting an IP address for a name;

instructions for automatically sending two DNS queries to a DNS server in response to the single DNS query received from the node, the two DNS queries including a first DNS query that includes the name and a second DNS query that includes the name, the two DNS queries conforming to two different IP protocols, wherein the node is in a domain conforming to a first one of the two different IP protocols and the DNS server is in a domain conforming to a second one of the two different IP protocols; and

instructions for automatically forwarding a first DNS reply that has been received from the DNS server to the node when the first DNS reply includes at least one answer resource record;

instructions for dropping a second DNS reply that has been received from the DNS server when the first DNS reply includes at least one answer resource record;

wherein forwarding the first DNS reply is performed independent of the protocol of the first DNS reply;

wherein sending the second DNS query is performed automatically without waiting for a DNS reply corresponding to the first DNS query to be received.

22. A device adapted for performing Network Address Translation and Protocol Translation, comprising:

a processor; and

a memory, at least one of the processor or the memory being adapted for;

receiving a single DNS query from a node, the single DNS query requesting an IP address for a name;

automatically sending two DNS queries to a DNS server in response to the single DNS query received from the node, the two DNS queries including a first DNS query that includes the name and a second DNS query that includes the name, the two DNS queries conforming to two different IP protocols, wherein the node is in a domain conforming to a first one of the two different IP protocols and the DNS server is in a domain conforming to a second one of the two different IP protocols;

receiving a first DNS reply from the DNS server;

receiving a second DNS reply from the DNS server subsequent to the first DNS reply; and

when the first DNS reply includes at least one answer resource record, automatically forwarding the first DNS reply to the node and dropping the second DNS reply, wherein forwarding the first DNS reply is performed independent of the protocol of the first DNS reply;

wherein sending the second DNS query is performed automatically without waiting for a DNS reply corresponding to the first DNS query to be received.

25. The device as recited in claim 22, at least one of the processor or the memory being further adapted for:

determining whether the first DNS reply includes at least one answer resource record;

wherein forwarding the first DNS reply is performed when the first DNS reply includes at least one answer resource record;

wherein dropping the second DNS reply is performed without determining whether the second DNS reply includes at least one answer resource record.