METHOD BASED ON THE COMBINATION OF THE UPnP AND STUN FOR NAT TRAVERSAL

• US 20110264739A1
• Filed: 05/03/2009
• Published: 10/27/2011
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Zhengzhou Seanet Technologies Company Limited
• Original Assignee: Institute Of Acoustics Chinese Academy Of Sciences
• Inventors: Wang, Jinlin, Su, Shaowei, Lu, Yifeng, Ren, Hao, Feng, Zhentan
• Granted Patent: US 8,560,607 B2
• Time in Patent Office: Days
• US Class Current: 709/204
• CPC Class Codes: H04L 61/256 NAT traversal
• 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 67/104 Peer-to-peer [P2P] networks

Abstract

The present invention relates to a method based on the combination of UPnP and STUN for NAT traversal. The method of the present invention effectively takes the advantages of UPnP and STUN. In particularly, when UpnP fails to traverse NAT, STUN is applied to perform the NAT traversal for the second time, so that the efficiency of the successful traversal is effectively improved. For the symmetric NAT traversal, a Port-Adding Sample Estimation method based on NAT adding port mapping is provided for port estimation, to avoid the defects resulted from the third-party agent and the blindness of the speculation approach. And, where both of the communication peers in the P2P streaming media system are behind NAT, the method that the part of the ordinary outer peers with the sufficient bandwidth acts as the Auxiliary-Relay peers is provided to release the pressure of the relay server so that the bottle-neck of the communication is broken through.

Claims

1. A method based on the combination of UPnP and STUN for NAT traversal, is characterized of including the steps as follow:

(1) the peer joining into the P2P streaming media system broadcast-searches the message for UPnP device in the internal net by the SSDP protocol;

void Search(char* name, const char* type), wherein, according to the requirement of UPnP standard, the parameter name is “

WANIPConnection” and

the parameter type is “

service”

meaning searching UPnP service;

(2) if searching UPnP service succeeds, sending the Port-Adding message to the NAT gateway control URL by the SOAP protocol;

void InvokeCommand(char* name, char* args), wherein the parameter name is control command “

AddPortMapping”

to UPnP device, and args is the several other parameters required by UPnP standard,

so that after adding port mapping the inner peer can connect with the outer peer for data communication, and NAT traversal is realized; and

(3) if searching fails, the peer initiates STUN model to perform NAT traversal for the second time;

void GetMapAddr(int&

extIP, int&

extPort, NatType&

natType), wherein the parameters extIP and extPort are the outer IP and Port obtained by STUN, and the parameter natType is the type of NAT determined during traversing.

2. The method based on the combination of UPnP and STUN for NAT traversal according to the claim 1, is characterized that the said step (3) further comprises:

(1) if NAT is Cone NAT, the said peer communicates with the other peers by the outer IP and Port obtained by STUN;

(2) if NAT is the symmetric NAT, the said peer performs NAT traversal by Port-Adding Sample Estimation method,

wherein the said Port-Adding Sample Estimation method includes the steps as follow;

the peer behind the symmetric NAT sends three connections to the STUN Server in the outer web in order, the server feeds back the mapping ports added by three connections, which are set into P₁, P₂ and P₃, and then the peer works as follow according to their changing rules,

2a) if P₁, P₂ and P₃ are the arithmetical progression, the way that the symmetric NAT adds port-mapping is to increase the original port in the tolerance d in order, so that the peer behind the symmetric NAT can communicate with the other peers by adding the tolerance d to the original outer port as its new outer communication port and filling it into the load of the data communication, and

2b) if P₁, P₂ and P₃ are not the arithmetical progression, the symmetric NAT adds port-mapping randomly, and the peer estimates the overall rule for port mapping according to the sample of port-adding,

the peer behind the symmetric NAT sends N−

3 connections again to the STUN server, to constitute the sample observations with the sample size of N together with three former connections, and the sample observation are in the interval [a, b ] divided into M sub-intervals (M<

N), wherein a=n₀<

n₁<

. . . <

n<sub>M−

1</sub><

n_M=b.

assuming that each sub-interval (n_i, n_i+1)(i=0, 1, . . . , M−

1) includes t_i observations, the formula as follows can be obtained by concluding based on Bernoulli law of large numbers and definition of probability density;

φ

_N(χ

)=t_i/NΔ

n_i (Δ

n_i=n_i+1−

n_i), wherein the graph of φ

_N(χ

) is the distribution histogram of the overall rule for port-mapping over [a, b],

and, a sub-interval in which the NAT mapping port distributes can be determined by observing the Δ

n_i with the relative high value of φ

_N(χ

), followed by speculating the next port-mapping added by the symmetrical NAT by Ergodic way in the said sub-interval, so that the speculating efficient is improved.

3. The method based on the combination of UPnP and STUN for NAT traversal according to the claim 1, is characterized of further comprising Peer Auxiliary-Relay method,

wherein if the both of communication peers in the P2P streaming media system are behind NAT, the peer will take the part of the outer ordinary communication peers with the sufficient bandwidth as its auxiliary relay peer.

4. The method based on the combination of UPnP and STUN for NAT traversal according to the claim 3, is characterized that the said Peer Auxiliary-Relay method further comprise:

1) the outer peers which have joined into the P2P streaming media system register with the relay server at first and the relay server will keep a list of the outer peers;

2) the relay server will probe all of the registered outer peers with heartbeat mechanism and select the M outer peers with the smallest RTT as the candidate of the auxiliary relay peers;

3) the inner peer registers with the relay server, and at the time of registering, the relay server transmits one list of the outer peers to the peer;

4) the inner peer randomly chooses the N (N<

M) outer peers to send connection, and selects the peer with the smallest RTT as its auxiliary relay peer while sending the registering information to the said auxiliary relay node; and

5) at the time of determining its own auxiliary relay peer, the inner peer obtains the information of the other communication peers registered on this auxiliary relay peer, so that when communicating with the other peers behind NAT, the inner peer will query the registering list of its auxiliary relay peer at first, wherein if the peer to be communicated is listed, the said auxiliary relay peer will be used to relay, otherwise the relay server will be used.