WO2008092340A1 - A keep-alive method, system of address forwarding list item and an agent service device - Google Patents

Abstract

A Keep-Alive method of address forwarding list item includes: the agent service device transmits the Keep-Alive message to the device having network address transferring function (s401); after receiving the Keep-Alive message, the device having network address transferring function restarts the time count of the address forwarding list item ageing time matched with the Keep-Alive message address (s402). A Keep-Alive system of the address forwarding list item and an agent service device are also provided. For the calling service in NGN, the present invention refreshes the corresponding address forwarding list item in the device having network address transferring function through transmitting the Keep-Alive message so as to resolve the question that there is a session, but there is not a corresponding address forwarding list item in the device having network address transferring function in the prior art.

Description

 The method for reserving the address forwarding entry, the system, and the proxy service device. The application is submitted to the Chinese Patent Office on January 29, 2007, and the application number is 200710006082.0, and the invention name is "the address forwarding entry method and system." The priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference.

Technical field

 The present invention relates to the field of communications technologies, and in particular, to a keep-alive method, system, and proxy service device for an address forwarding entry.

Background technique

 With the development of IP technology, VoIP (voice over Internet Protocol) technology is gradually favored. NGN (Next Generation Network) based on SoftSwitch (softswitch) technology is gradually being adopted by major operators. And the recognition of the company. The NGN network structure is shown in Figure 1. It includes: service management layer, network control layer, core switching layer, and edge access layer. Among them, the business management layer includes: iOSS (integrated operation support system), policy server, U-NICA (Universal Network Intelligent Core Architecture) application server, IN (Intelligent Network, Intelligent Network) The network control layer includes a softswitch device; the core switch layer includes a packet core network; the edge access layer includes: a broadband access device, such as an IAD (Integrated Access Device); PSTN (Public Switched Telephone Network) Telephone network) equipment; PLMN (Public Land Mobile Network), such as 2G/3G access equipment; user equipment such as SIP (Session Initiation Protocol)/H.323 telephone, POTS (Plain) Old Telephone Service, plain old telephone service) and user equipment such as 2G/3G terminals.

NGN uses a packet-based transmission mode and a unified protocol to support diverse access modes. By separating services from call control, call control and bearer separation, a relatively independent service system is implemented, allowing services and networks to be separately provided and independent. development of. This kind of business is independent of the flexibility of the network, meets the needs of users to continuously update their business, and makes the network sustainable. In the signaling interaction between NGN services, in order to ensure normal addressing and routing of media stream packets, the protocol message payload usually carries address information, such as RTP (Real-time Transport) dynamically negotiated during signaling interaction. Protocol, Real-Time Transport Protocol) or RTCP (Real-time Transport Control Protocol) address and port information.

 In order to solve the problem of IP address exhaustion and network resource contention, NAT (Net Address Translation) needs to be added to the internal network edge of the router connected to the backbone network. As shown in Figure 2, NAT is used in the prior art. The NGN network structure diagram of the device. When the IP data packet sent by the internal network reaches the NAT device, the NAT is responsible for converting the internal network IP address into the legal IP address of the backbone network. When an externally sent data packet arrives at the NAT, the NAT is in the mapping table saved by referring to the NAT. The information is converted into the IP address of the internal network and forwarded to the internal terminal. At the same time, in order to improve the security of the internal network, it is necessary to use a firewall at the internal network exit to limit the types and traffic entering the internal network packets. The IP-based voice and video communication protocol requires the terminal to establish a data communication channel by using the IP address and port number, so there is a dilemma: NGN terminals must listen to incoming calls at any time, but the firewall does not allow the external network. Any unsolicited packets are passed.

 When the NGN service traverses a device with a network address translation function such as a NAT device or a firewall, the NAT/firewall only translates the address and port number of the IP packet header, and H.323, SIP, and MGCP (Media Gateway Control Protocol, The real media stream information of the protocol such as the media gateway control protocol is transmitted in the payload of the IP packet, and the private network address in the payload cannot be mapped to the public network address by the NAT/firewall and transmitted to the peer end, thus crossing the NAT/ The firewall is unable to communicate.

 In order to implement the NGN service traversing the NAT device/firewall, the prior art provides an ALG (Application Level Gateway) technology. As an enhancement of the NAT/firewall, the ALG also translates the corresponding address information field embedded in the IP header payload during address translation, for example, rewriting the Contact field in the SIP protocol Register message. However, this solution requires upgrading the NAT device/firewall to support the ALG function. This is not easy to implement for most enterprise networks that have deployed NAT devices, and the existence of a session but no corresponding NAT forwarding entries still exists. .

Another scheme for the NGN service to traverse the NAT/firewall is Full Proxy. This solution is to add a proxy service device outside the NAT device/firewall. As shown in Figure 3, it is an NGN with a proxy service device in the prior art. Network structure diagram. The signaling flow and media flow of all calls are transferred through the proxy service device. Softswitch when adding a proxy service device outside the NAT device/firewall The incoming message is proxied by the proxy service device. Since the proxy service device proxyes the signaling flow and the media stream of the call, and records the information on the softswitch side and the terminal side, it can traverse the NAT/firewall.

 The proxy service device stores the registration information of the NAT/firewall user, including the IP address and port number of the NAT/firewall, and also retains the corresponding NAT entry on the NAT/firewall device. However, the aging time of the address mapping entry in the NAT device/firewall is too long. If the entry is occupied for a long time and the NAT entry is not used, the aging time of the NAT entry is shorter. The entry will age after it times out. Therefore, some entries may be deleted during the session, because the entries on the device with the network address translation function are aged out, which causes the session to exist but the device with the network address translation function does not have the corresponding address forwarding entry. .

Summary of the invention

 The embodiment of the present invention provides a method, a system, and a proxy service device for a message forwarding entry in a network address translation device, so as to solve the problem that the proxy service device session exists in the prior art but has a network address translation function. The problem corresponding to the address forwarding entry.

 An embodiment of the present invention provides a keepalive method for an address forwarding entry, including:

 The proxy service device sends a keep-alive message to the device with the network address translation function;

 After receiving the keep-alive message, the device with the network address translation function re-times the aging time of the address forwarding entry that matches the keep-alive message address.

 The embodiment of the invention provides a keep-alive system for an address forwarding entry, including:

 a proxy service device, configured to send a keep-alive message;

 The device with the network address translation function is configured to receive the keep-alive message sent by the proxy service device, and re-time the aging time of the address forwarding entry that matches the keep-alive message address.

 An embodiment of the present invention provides a proxy service device, including:

The forwarding entry detecting unit is configured to detect whether the source IP address and the destination IP address of the proxy service device are respectively a device IP address with a network address translation function and a proxy service device IP address; the source port number and the destination port number are respectively A forwarding entry having a device port number of the network address translation function and a proxy service device port number; and sending a keep-alive message to the device having the network address translation function. Compared with the prior art, the embodiment of the invention has the following advantages:

 The present invention solves the problem that the call service in the NGN refreshes the corresponding address forwarding entry on the device with the network address translation function by sending the keep-alive message, thereby solving the problem that the session on the proxy service device exists but has the network address translation function. There is no problem with the corresponding address forwarding entry.

DRAWINGS

 1 is a structural diagram of a NGN network in the prior art;

 2 is a structural diagram of an NGN network having a NAT device in the prior art;

 3 is a structural diagram of an NGN network with a proxy service device in the prior art;

 4 is a flowchart of a keep-alive method for an address forwarding entry according to an embodiment of the present invention; FIG. 5 is a flowchart of setting a keep-alive message by a proxy service device according to an embodiment of the present invention;

 6 is a structural diagram of a keep-alive message in an embodiment of the present invention;

 Figure 7 is a schematic view of another embodiment of the present invention;

 Figure 8 is a simplified schematic view of another embodiment of the present invention;

 FIG. 9 is a structural diagram of a keep-alive system of an address forwarding entry according to an embodiment of the present invention; FIG. 10 is a structural diagram of a message generating unit in an embodiment of the present invention.

detailed description

 Corresponding software in embodiments of the invention may be stored in a computer readable storage medium. The embodiment of the present invention implements a keep-alive mechanism on the proxy service device, and periodically sends a Keep-Alive message to the NAT device/firewall, so as to periodically refresh the address forwarding entry on the NAT/firewall device to ensure NAT/ When there is a session between the firewall device and the proxy service device, the address forwarding entries on the NAT/firewall will not be aged.

 The embodiment of the present invention provides a keepalive method for an address forwarding entry. As shown in FIG. 4, the method includes the following steps: Step s401: The proxy service device sends a keep-alive message to a device with a network address translation function. Generally, the refresh interval of the aging mechanism of the address forwarding entry is about 30 seconds, and the interval for sending keep-alive packets is smaller than the refresh interval of the aging time.

Step s402: After receiving the keep-alive message, the device with the network address translation function obtains the IP header, the Ethernet header, and the UDP (User Datagram Protocol) header of the keep-alive message, and determines that the network has a network. Whether the address translation function matches the address forwarding entry, and the address matches: source IP address, destination IP address, source port number, and destination port number. Match. If yes, the aging time of the address forwarding entry is re-timed. For example, if the aging time has expired to 2.5 seconds, the aging time is re-timed from 0. If not, the aging time is reported. The text does not deal with it. In addition, if the content of the keep-alive message carries a message sent by the proxy service device to the device with the network address translation function, the message is extracted and processed accordingly.

 Before the step s401, the proxy service device sets the keepalive message, and the source port number and the destination port number in the keep-alive packet are respectively the port number of the proxy service device and the device port number with the network address translation function; The source IP address and the destination IP address are the IP addresses of the proxy service device and the device with network address translation function, respectively.

 As shown in FIG. 5, it is a flowchart of setting a keep-alive message by the proxy service device in the embodiment of the present invention. The process of setting up keep-alive 4 is as follows:

 Step 501: Find a destination address IP header of the keep-alive packet by searching the routing table.

 Step 502: Find an Address Resolution Protocol (ARP) table to obtain an Ethernet header of a destination MAC (Medium Access Control) address;

 In step 503 and step 504, the IP header and the Ethernet header of the keepalive text are constructed according to the IP header and the Ethernet header. Step 505: Determine whether the content of the keep-alive message is preset, for example, the alarm indication information of the lower-level device, or other Information, if the message content has been configured, go to step 506, if the message content is not configured, then go to step 507;

 Step 506: Fill in the content of the message into the content part of the message of the keep-alive message;

 Step 507, fill in the HELLO information;

 Step 508: Construct a UDP header and UDP data of the keep-alive message, where the content of the keep-alive message is in the UDP data; and then complete the setting of the keep-alive message.

 6 is a structural diagram of a keepalive message according to an embodiment of the present invention. The keep-alive message includes a 4-byte Ethernet header, a 20-byte IP header, an 8-byte UDP header, and an arbitrary byte of UDP data. The IP header specifically includes: a 1-byte version and length, a 1-byte differential service code point, a 2-byte total length, a 2-byte ID, a 2-byte fragmentation flag, and an offset, 1 Byte lifetime, 1-byte protocol number, 2-byte IP checksum, 4-byte source IP address, and 4-byte destination IP address; UDP header specifically includes: 2-byte source port, 2 Byte destination port, 2 bytes length, and 2 byte checksum.

In order to prevent there is no session between the device with network address translation and the proxy service device The resource waste caused by setting or sending the keep-alive packet, before step s401, further includes: the proxy service device detects whether the source IP address and the destination IP address are the IP address of the device having the network address translation function, and The proxy service device IP address; the source port number and the destination port number are forwarding entries of the device port number and the proxy service device port number respectively having the network address translation function. If the address forwarding entry exists, it proves that a session exists. Set or send keep-alive messages.

 In the embodiment of the present invention, the call service in the device with the network address translation function is configured to refresh the corresponding address forwarding entry on the device with the network address translation function by sending the keep-alive message to ensure that the device has the network address translation function. When a session exists, the corresponding address forwarding entry exists on the device with the network address translation function. In addition, the device with the network address translation function in the embodiment of the present invention may be a NAT device or a firewall device.

 Another embodiment of the present invention is shown in Fig. 7. I represents the address of the IAD, A represents the NAT-transformed address, B represents the proxy service device receiving address, C represents the proxy service device transmission address, and D represents the softswitch address. Assume that the middle router is ignored, C and D are on the same network segment, and A and B are on the same network segment. Figure 7 is simplified: I, A, B, C, and D represent the IP addresses of the devices, respectively. Port I, Port A, Port B, Port C, Port D represent the corresponding ports, and reports sent and received from the terminal IAD. The address translation process experienced by the text, as shown in Figure 8:

 For the packets sent from the IAD: The source IP address and source port of the packet are translated on the NAT, and the following entries are created:

 I: Port I -> B: Port B ==> A: Port A -> B : Port B ( 1 )

 The source IP address, source port, destination IP address, and destination port of the packet are translated on the proxy service device, and these key values are recorded. The following entries are created:

 A: Port A -> B: Port B ==> C: Port C -> D : Port D ( 2 )

 The packet sent back from the softswitch side is returned as follows: The source IP address, source port, destination IP address, and destination port of the packet are converted on the proxy service device, and these key values are recorded and established. 3⁄4 port entry:

 D: Port D -> C: Port C ==> B: Port B -> A : Port A ( 3 )

 The source IP address and source port of the packet are translated on the NAT. The following entries are created:

B: Port B -> A: Port A ==> B: Port B -> I : Port I ( 4 ) Since the proxy service device receives the NAT-based message at address B, the NAT address + port number is recorded, and is converted to the address C by the proxy service device and forwarded to the softswitch D. Therefore, the proxy service device can utilize the recorded NAT address. + Port number, A and Port A, sends Keep-Alive messages to the NAT device. If the above-mentioned entry (2) exists, indicating that the signaling flow exists, and the routing table of B to A is valid and the ARP table is valid, the following Keep-Alive packet flow is established according to the entry:

 D: Port D -> C: Port C ==> B: Port B -> A : Port A ( 5 ) The packets sent from A to B are actually assembled by the proxy service device. The basis for the Keep-Alive message assembly is: The source is the address + port number of the proxy service device, namely: B and Port B; The destination is the address + port number of the NAT device, namely: A and Port A; D: Port D -> C: Port C is an entry.

 The embodiment of the present invention provides a keep-alive system for an address forwarding entry, as shown in FIG. 9, including a device 100 having a network address translation function and a proxy service device 200. The proxy service device 200 is configured to send a keep-alive message to the device 100 having the network address translation function; and the device 100 having the network address translation function is configured to receive the keep-alive message and match the address of the keep-alive message address. The oldest time of the forwarding entry is re-timed, where the address matches: Source IP address, destination IP address, source port number, and destination port number match.

 The proxy service device 200 further includes a keep-alive message transmitting unit 201 and a forwarding entry detecting unit 202. The forwarding entry detection unit 202 is configured to detect whether the proxy service device 200 has a source IP address and a destination IP address, respectively, an IP address of the device 100 having the network address translation function and an IP address of the proxy service device 200; the source port number and The destination port number is a forwarding entry of the port number of the device 100 having the network address translation function and the port number of the proxy service device 200, and notifys the keep-alive packet sending unit 201 to send a keep-alive message when it exists; The text sending unit 201 is configured to send a keep-alive message to the device 100 having the network address translation function. The message is sent to the keep-alive message transmitting unit 201 under the trigger of the forwarding entry detecting unit 202 to transmit the keep-alive message.

The proxy service device may further include a detection timer unit 204 for triggering the forwarding entry detection unit 202 to detect when the timeout occurs. The keep-alive packet generating unit 203 further includes: an IP header setting sub-unit 2031, an Ethernet header setting sub-unit 2032, a message content adding sub-unit 2033, and a UDP setting sub-unit 2034, as shown in FIG. The IP header setting sub-unit 2031 obtains the IP header of the keep-alive packet by searching the routing table; the Ethernet header setting sub-unit 2032 obtains the Ethernet header of the keep-alive packet by searching the ARP table; the packet content adding sub-unit 2033 adds keep-alive The content of the message, the content of the message is HELLO or pre-configured information; the UDP setting sub-unit 2034 sets the UDP header and UDP data of the keep-alive message, wherein the UDP data stores the content of the keep-alive message.

 The device 100 having the network address translation function further includes: a matching processing unit 101, an aging timer refresh unit 102, an aging timer 103, and an address forwarding entry deletion unit 104. The matching processing unit 101 is configured to determine an address forwarding entry that matches the received keep-alive message address; the address forwarding entry deletion unit 104 is configured to delete the address forwarding entry when the aging timer 103 times out; The refreshing unit 102 is configured to cause the aging timer 103 to re-clock when the matching processing unit 101 finds an address forwarding entry that matches the received keep-alive address.

 In the embodiment of the keep-alive system of the address forwarding entry of the present invention, the call forwarding service in the NGN is configured to refresh the corresponding address forwarding entry on the device with the network address translation function by sending the keep-alive message to ensure the network address translation function. When a session on the device exists, the corresponding address forwarding entry exists on the device with the network address translation function. In addition, the device with the network address translation function in the embodiment of the present invention may be a NAT device or a firewall device.

 The above disclosure is only a few specific embodiments of the present invention, but the present invention is not limited thereto, and any changes that can be considered by those skilled in the art should fall within the protection scope of the present invention.

Claims

Rights request  A keep-alive method for an address forwarding entry, which is characterized by:  The proxy service device sends a keep-alive message to the device with the network address translation function;  After receiving the keep-alive message, the device with the network address translation function re-times the aging time of the address forwarding entry that matches the keep-alive message address.  The method of maintaining the address forwarding entry according to claim 1, wherein the proxy service device further includes: the proxy service device setting office before sending the keep-alive message to the device having the network address translation function The live-keeping message.  The method for maintaining the address forwarding entry according to claim 2, wherein before the proxy service device sends the keep-alive message to the device having the network address translation function, the method further includes: The function device IP address and the proxy service device IP address; the source port number and the destination port number are respectively forwarding entry entries of the device port number and the proxy service device port number having the network address translation function.  The method of maintaining the address forwarding entry according to claim 1, wherein the time interval for sending the keep-alive packet is smaller than the aging time.  The keepalive method of the address forwarding entry according to claim 1, wherein the keep-alive packet specifically includes: an Ethernet header, an IP header, a datagram protocol header, and datagram protocol data.  The keep-alive method of the address forwarding entry according to claim 5, wherein the content of the keep-alive message includes HELLO or pre-configured information in the datagram protocol data.  The keepalive method of the address forwarding entry according to claim 5, wherein the source port number and the destination port number in the datagram protocol header in the keep-alive message are respectively port numbers of the proxy service device. And a device port number having a network address translation function; the source IP address and the destination IP address in the IP header in the keep-alive message are respectively an IP address of the proxy service device and the device having the network address translation function.  8. A keep-alive system for an address forwarding entry, comprising:  a proxy service device, configured to send a keep-alive message; The device with the network address translation function is configured to receive the keep-alive message sent by the proxy service device, and re-time the aging time of the address forwarding entry that matches the keep-alive message address. 9. The keep-alive system of the address forwarding entry according to claim 8, wherein the proxy service device comprises:  The forwarding entry detecting unit is configured to detect whether the source IP address and the destination IP address of the proxy service device are respectively a device IP address with a network address translation function and a proxy service device IP address; the source port number and the destination port number are respectively A forwarding entry having a device port number of the network address translation function and a proxy service device port number; and sending a keep-alive message to the device having the network address translation function.  10. The keep-alive system of the address forwarding entry according to claim 8, wherein the device having the network address translation function comprises: a matching processing unit, an aging timer, an aging timer refreshing unit, and an address forwarding entry. Delete unit;  The matching processing unit is configured to determine an address forwarding entry that matches the received keep-alive message address;  The address forwarding entry deletion unit is configured to delete the address forwarding entry when the aging timer expires;  And the aging timer refreshing unit is configured to: when the matching processing unit determines an address forwarding entry that matches the address of the keep-alive message, the aging timer is re-timed.  11. A proxy service device, comprising:  The forwarding entry detecting unit is configured to detect whether the source IP address and the destination IP address of the proxy service device are respectively a device IP address with a network address translation function and a proxy service device IP address; the source port number and the destination port number are respectively A forwarding entry having a device port number of the network address translation function and a proxy service device port number; and sending a keep-alive message to the device having the network address translation function.  The proxy service device according to claim 11, further comprising: a keep-alive message generating unit, configured to set the keep-alive message.  The proxy service device according to claim 12, wherein the keep-alive message generating unit comprises: The IP header setting sub-unit is configured to obtain an IP header of the keep-alive message by searching the routing table; The Ethernet header setting sub-unit is configured to obtain the Ethernet header of the keep-alive message by searching the ARP table; the text content is added to the sub-unit, and is used to add the keep-alive message content;  The datagram protocol setting sub-unit is used to set the datagram protocol header and datagram protocol data of the keep-alive message.  The proxy service device according to claim 11, further comprising: a detection timer unit, configured to trigger the forwarding entry detection unit to perform a check when the timer expires