INTERWORKING SYSTEM BETWEEN IP NETWORKS USING DIFFERENT IP ADDRESS FORMAT, APPLICATION LAYER GATEWAY (ALG) SERVER, STUN SERVER, NETWORK ADDRESS TRANSLATOR, INTERWORKING METHOD THEREOF, AND SIP MESSAGE ROUTING METHOD THEREOF

• US 20110191493A1
• Filed: 02/11/2011
• Published: 08/04/2011
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: KT Freetel Co., Ltd. (KT Corporation)
• Original Assignee: KT Freetel Co., Ltd. (KT Corporation)
• Inventors: Lee, Ho-Jin, Bak, Sang-Man, Lee, Jang-Won
• Granted Patent: US 8,346,962 B2
• Time in Patent Office: Days
• US Class Current: 709/238
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• 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 61/2585 through application level gateway [ALG]
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/104 in the network
• CPC Class Codes: H04L 65/1043 Gateway controllers, e.g. media gateway control protocol [MGCP] controllers
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]

Abstract

Disclosed are an interworking system between IP networks using different IP address format, an application layer gateway (ALG) server, a network address translator, an interworking method, and a SIP message routing method. The interworking system between a local network using a private IP and a public network using a public IP includes a STUN server and an application layer gateway (ALG) server. The STUN server provides binding information of header information of a public IP binding request. The application layer gateway (ALG) server performs a public IP binding request with header information changed by IP masquerading, and performs routing by applying the received binding information to media receiving address information of a SIP message.

Claims

1. A SIP message routing method of a node for interworking between a local network using a private IP address and a public network using a public IP address, the SIP message routing method comprising:

(a) checking a transmitting subject and a method of the received SIP message;

(b) applying the network address translation based on the checked message transmitting subject and the method to the media and RTCP receiving address information of the SIP message;

(c) specifying the address of the node selected based on the checked message transmitting subject in routing path information of the SIP message; and

(d) routing the SIP message to the corresponding destination address.

2. The SIP message routing method of claim 1, wherein (b) comprises:

translating the media and RTCP receiving address information into a public IP, mapping the public IP on the pre-translation information, and temporarily storing mapping information results when the transmitting subject is a local network and the method is a session invite request message; and

storing the temporarily stored mapping information in a SIP address allocation table when the transmitting subject is a public network and the method is a response message to the session invite request message.

3. The SIP message routing method of claim 2, wherein (c) comprises:

specifying a public IP address of the node when the message transmitting subject is a local network; and

specifying a private IP address of the node when the message transmitting subject is a public network.

4. The SIP message routing method of claim 3, further comprising, after (d), receiving a SIP service request message by using a private IP address of the node when the transmitting subject is a local network;

receiving a SIP service request message by using a public IP address of the node when the transmitting subject is a public network; and

routing the received message to the corresponding destination.

5. The SIP message routing method of claim 4, wherein (b) further comprises:

applying the network address translation to transport information of the SIP message, the transport including one of host name or network address information of the transmitting subject.

6. The SIP message routing method of claim 5, wherein (b) comprises performing the network address translation by using a network address translation table.

7. A SIP message routing method of a node for interworking between a local network using a private IP address and a public network using a public IP address, the SIP message routing method comprising:

(a) transmitting a public IP binding request in which header information is inserted in media and RTCP receiving address information in the private IP format extracted from the SIP message received from a call transmitting terminal;

(b) receiving a public IP binding response including the header information translated into a public IP; and

(c) applying the media and RTCP receiving address information translated into a public IP to the SIP message, and transmitting the SIP message to a call receiving terminal.

8. The SIP message routing method of claim 7, wherein the method comprises, before (a):

receiving the SIP message from the call transmitting terminal;

checking a transmitting subject and a method of the SIP message; and

determining whether the networks of the transmitting subjects of the SIP message correspond to each other and whether the message is a request message or a response message.

9. The SIP message routing method of claim 8, wherein (a) comprises:

extracting m/c/a attribute values in the SDP of the SIP message when the networks of the transmitting subjects of the SIP message are different and the message is a session request message; and

changing the header information of the public IP binding request with the extracted m/c/a attribute values.

10. The SIP message routing method of claim 7, wherein (c) comprises:

changing the media and RTCP receiving address information included in the SIP message with the media and RTCP receiving address information translated into the public IP;

selecting the public IP address or the private IP address based on the transmitting subject of the SIP message;

specifying the selected IP address in routing path information of the SIP message; and

transmitting the SIP message in which the media and RTCP receiving address information translated into the public IP and the routing path are specified.