TRAVERSAL OF SYMMETRIC NETWORK ADDRESS TRANSLATOR FOR MULTIPLE SIMULTANEOUS CONNECTIONS

• US 20110035501A1
• Filed: 10/22/2010
• Published: 02/10/2011
• Est. Priority Date: 03/05/2008
• Status: Active Grant

• Current Assignee: Sony Interactive Entertainment Inc. (Sony Group Corp.)
• Original Assignee: Sony Computer Entertainment Incorporated (Sony Group Corp.)
• Inventors: Takeda, Yutaka
• Granted Patent: US 8,015,300 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: H04L 2101/668 Internet protocol [IP] address subnets
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 61/2564 for a higher-layer protocol, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 61/2575 using address mapping retrieval, e.g. simple traversal of user datagram protocol through session traversal utilities for NAT [STUN]
• CPC Class Codes: H04L 61/2578 without involvement of the NAT server

Abstract

Handling of multiple connections during NAT traversal for a node behind a symmetric NAT is disclosed. The likelihood of connection failure during symmetric NAT traversal may be reduced by serializing critical time windows after port prediction. Once a connection request has been sent for a first connection, port prediction for a subsequent connection may be delayed until a connectivity check has begun for the first connection. This process may be repeated to handle NAT traversal for multiple simultaneous connections to different nodes.

Claims

1. A method for peer-to-peer connection over a network between a first node behind a first symmetric network address translator (NAT) and two or more other nodes, the method comprising:

a) sending a connection request message containing the list of predicted transport addresses from the first node to a second node;

b) receiving a provisional response to the connection request message at the first node;

c) performing a check of connectivity between the first node and the second node using the predicted transport addresses; and

d) delaying port prediction for communication between the first node and a third node until after d) has begun.

2. The method of claim 1, further comprising:

e) after d), performing the port prediction for communication between the first node and a third node, wherein the first node constructs a list of predicted transport addresses on the first NAT;

f) sending a connection request message containing the list of predicted transport addresses from the first node to a third node;

g) performing a check of connectivity between the first node and the third node using the predicted transport addresses.

3. The method of claim 2, further comprising:

h) delaying port prediction for communication between the first node and a fourth node until after g).

4. The method of claim 1 wherein performing the connectivity check includes sending Session Traversal Utility for NAT (STUN) packets from the second node to the one or more transport addresses provided by the first node in the connection request message.

5. The method of claim 4 wherein performing the connectivity check further includes sending a STUN packet response from the first node to the second node, wherein the STUN packet response includes a transport address of an external port on the first NAT through which one of the STUN packets sent from the second node reached the first node.

6. The method of claim 1, further comprising:

waiting for a period of time T_W after a), but before b) in response to a message from the second node indicating that the second node is queued for connection to another node;

canceling the communication session between the first node and the second node; and

repeating a), b), c), d),

wherein the amount of time T_W is greater than or equal to zero and less than a timeout for connectivity failure between the first and second nodes.

7. The method of claim 1, wherein c) includes sending one or more test packets from the first node to the second node using a transport address from the list of predicted transport addresses.

8. The method of claim 10 wherein d) includes delaying port prediction for communication between the first node and the third node until after a first of the one or more test packets has been sent.

9. A node, comprising:

a processor;

a memory;

a network interface; and

instructions embodied in the memory and configured for execution on the processor, the instructions comprising;

a set of instructions that, when executed, cause the node to;

i) send a connection request message containing the list of predicted transport addresses from the node to a second node;

ii) receiving a provisional response to the connection request message at the node;

iii) performing a check of connectivity between the first node and the second node using the predicted transport addresses; and

iv) delaying port prediction for communication between the node and a third node until after iii) has begun.