KR100451167B1 - Gateway system and packet processing method thereof - Google Patents

Abstract

The present invention relates to a gateway system and a packet processing method thereof, and more particularly, to enable communication between terminals in a network and internet access of terminals without changing any existing network settings of terminals in a network serviced by the gateway. . The present invention for this purpose is a gateway system for communication between terminals and the Internet access of the terminal, means for transmitting a proxy ARP response message to the terminal when the ARP request is received from the terminal having the IP address of the previous network, and And means for performing packet routing with reference to ARP cache information for communication between a terminal having an IP address of a network and a terminal having a different IP band from the terminal.

Description

GATEWAY SYSTEM AND PACKET PROCESSING METHOD THEREOF

The present invention relates to a gateway (Gateway) implementation, and more particularly, to a gateway system and a packet processing method thereof does not require changing the existing network configuration of the terminal.

The research and development of communication technology attempted since the late 1960s enabled packet-based data communication, and in 1975 the TCP / IP specification for packet-based data communication was determined.

TCP / IP (Trnasmission Control Protocol / Internet Protocol) generally tends to separate TCP and IP into separate protocols, but TCP / IP does not refer to each protocol, but rather to TCP / IP communication. It means many protocols involved.

One of the TCP / IP protocols is the Address Resolution Protocol (ARP).

This corresponds to the data link layer of OSI, which sends a broadcast packet on the network to receive a response from the machine and dynamically converts the IP address into a MAC address, which is a physical address of hardware.

In general, the TCP / IP-based network is configured such that the gateway 110 assigns an IP address to the terminal 120 to enable internet communication and intra-network communication.

The terminal 120 may be set to a network automatically or manually.

First, if the terminal 120 is automatically configured for the network, the DHCP server 111 gives the terminal 120 an available IP address used in the network and a default gateway IP address for performing the Internet access service of the network. do.

The available IP address assigned by the DHCP server 111 to the terminal 120 becomes a public IP address 101 or a private IP address 102 according to the IP address granting policy of the network.

The gateway 110 becomes a default gateway for the terminal 120 having a public IP address or a private IP address.

On the contrary, if the network configuration of the terminal 120 is made manually, when the terminal 120 is correctly set to the IP address and default gateway address of the network to which the terminal 120 belongs (103) and the terminal 120 belongs to the previous one. If it is set to the IP address of the existing network and the default gateway address (104), it can be considered. Here, in the former case, the Internet connection is normally performed (107). In the latter case, network access service is impossible unless the gateways support the Mobile IP function due to incorrect network configuration information.

However, if the mobile IP technology is used, the terminal 120 can freely access any network on the Internet, which maintains its IP as it is.

However, for this purpose, there is a requirement that the terminal 120 should be equipped with Mobile IP technology called a home agent in the gateway of the network to which the terminal 120 originally belongs, and the foreign agent technology should be mounted in the gateway of the network to which the terminal 120 currently belongs. do.

The connection state of the general gateway 210 is installed between the terminal 220 and the Internet 230 as shown in the configuration diagram of FIG. 2 to handle the flow of inbound packets and outbound packets. It is composed.

If the terminal 220 is configured as an automatic network and is assigned a public IP or a private IP, and the gateway 210 operates as a default gateway for the terminal, outbound packets destined for the Internet are routed through the gateway.

The terminal 220 transmits the packet to the default gateway by determining that the packet is an outbound packet destined for the Internet using its IP address and netmask information.

At this time, for packet transmission to the gateway 210, the terminal 220 sends an ARP (Address Resolution Protocol) request message to find the layer 2 MAC address of the default gateway.

In this case, since the default gateway of the terminal 220 is set correctly, the target IP address of the ARP request message matches the IP address of the gateway 210, and the gateway 210 responds with an ARP response message. A packet is sent to the gateway 210 for routing.

However, conventionally, when the terminal is set to the IP address and default gateway information of the network to which the terminal previously belongs, the target IP address of the ARP request message is identical to the IP address of the gateway of the previous network. There is a problem that there is no response and packet routing fails. That is, conventionally, if the terminal does not change its network configuration information to the IP address and default gateway address of the network to which the terminal belongs, packet routing will fail.

In addition, conventionally, even when using the existing DHCP-based automatic network configuration information setting function, the terminal requests the setting of 'get IP address automatically', and once set, the network configuration information of the previous network to which the terminal belongs It has the disadvantage of being deleted. In other words, the conventional technology must change the setting to 'Automatically obtain an IP address' setting so as not to go through the manual configuration process in the terminal, which requires a change of the configuration information and at the same time the network configuration of the network to which the terminal belongs. The disadvantage is that the information is deleted.

However, with the recent rise of home network technology, Internet access terminals of one-sided PCs are beginning to expand to various terminals, such as digital information appliances, and users of these information appliances are inferior in technology familiarity to conventional PC users. Therefore, the configuration process for accessing these terminals to the Internet is aimed at a so-called 'Zero configuration' that is transparent to the general user.

Accordingly, the present invention provides a gateway system and a packet thereof invented to enable communication between terminals in a network and internet access of terminals without changing any existing network settings of terminals in a network serviced by a gateway to improve the conventional problems. The purpose is to provide a treatment method.

That is, the present invention uses a middleware technology in which discovery between terminals is automatically performed in a small network such as a home network, thereby enabling communication between terminals in the network and internet access of the terminals even if the terminals do not change existing network configuration information. The purpose is to make it.

1 is a configuration diagram of a TCP / IP based network.

2 is a configuration diagram showing a connection state of a general gateway.

3 is an operation flowchart showing an ARP request packet processing procedure in an embodiment of the present invention.

4 is a flowchart illustrating a packet routing process in an embodiment of the present invention.

5 is an operational flowchart for inbound packet flow processing in an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

210: gateway 220: terminal

In order to achieve the above object, the present invention provides a gateway system for communication between terminals and Internet access of a terminal in a network, wherein a response to an ARP request packet transmitted by a terminal to know the MAC address of its default gateway is simulated. It is characterized in that it is configured to enable the terminal having a proxy (RP) ARP unit to communicate with a terminal having an IP band different from its own IP band.

The gateway system is configured to achieve packet routing by further utilizing IP / MAC / interface ARP cache information of terminals in a network obtained through a broadcasting mechanism of a middleware technology in which discovery between terminals is automatically performed in a network such as a home network. It is characterized by enabling communication between terminals using different IP bands.

The middleware technology is UPnP.

The gateway system converts the IP address of the previous network of the terminal into a NAT (Network Address Translation) public IP address for the outbound packet flow from the terminal having the IP address of the previous network to the Internet, and the terminal has its own IP band. It is characterized in that it is configured to communicate with the terminal on the Internet using a different IP band. However, if the terminal having the IP address of the previous network is in the same network as the terminal using a different IP band from its own IP, the IP / IP of the terminals in the network acquired through the broadcasting mechanism of the middleware technology without NAT address translation. Configure packet routing to further leverage MAC / interface ARP cache information.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Gateway 210 for the embodiment of the present invention is installed between the terminal 220 and the Internet 230, as shown in the configuration of Figure 2 of the inbound (inbound) and outbound (outbound) packet It is configured identically to the prior art to process the flow.

The operation and the effect of the embodiment of the present invention configured as described above will be described with reference to the operation flowcharts of FIGS. 3 to 5.

The gateway 210 may communicate between terminals through a broadcast mechanism of a middleware technology in a small network such as a home network so that the terminal 220 may enable communication with the terminals in the network and the Internet even if the terminal 220 does not change the existing network configuration information. Let discovery be automatic.

In addition, the terminal 220 informs its existence at the initial boot-up through a middleware broadcasting mechanism using IP multicast.

By going through this process, the terminals in the network have their mutually synchronized IP / MAC / interface ARP cache information.

The middleware technology in the above is assumed to be Universal Plug and Play (UPnP).

First, the ARP request packet processing process of the gateway in the embodiment of the present invention will be described with reference to the operation flowchart of FIG.

The terminal 220 transmits an ARP request packet to find the MAC address of its default gateway in order to route a packet destined for an IP band different from its own IP band. Here, it is assumed that the gateway 210 operates as a default gateway of the terminal 220.

Therefore, the default gateway 210 receives the ARP request packet and determines whether the target IP at the terminal 220 is the same as its own IP (My IP), and if it is determined that the target IP and the own IP are the same, the ARP response packet is received. Send it. (S301 ~ S303)

In addition, the gateway 210 transmits an ARP request packet to a default gateway of the terminal 220 so that the terminal 220 having an IP address of a network belonging to the previous one communicates with a terminal having a different IP band from its own IP band. Implement a proxy ARP unit that virtually performs the response when sending a message. (S301, S302, S304, S306)

That is, when the gateway 210 receives the ARP request packet and determines that the target IP at the terminal 220 is not the same as its IP, the gateway 210 checks whether the target IP address exists in the ARP cache table. S304)

Accordingly, if the target IP address does not exist in the ARP cache table, the gateway 210 sends a proxy ARP response message, sets the target IP of the ARP request message to the ARP sender IP, and sets its MAC address to the ARP target HA. (S306)

Thereafter, the gateway 210 may receive a packet destined for a terminal of another IP band from a terminal having an IP address of a previous network.

That is, when implementing the Proxy ARP unit as described above, the above-mentioned ARP cache information is referred to so as not to interfere with communication between terminals having the same IP band in the network, and the ARP request packet is the ARP cache entry for the target IP. Proxy ARP response is made only if it does not exist (S306).

In addition, in the embodiment of the present invention, the gateway 210 uses the ARP cache information described above in packet routing to enable communication between terminals in a network using different IP bands.

A packet routing process in which the gateway 210 further uses ARP cache information will be described with reference to the operation flowchart of FIG. 4.

First, upon receiving a packet, the gateway 210 checks whether a destination address exists in the ARP cache table. (S401, S402).

At this time, if the destination address of the packet does not exist in the ARP cache information, the gateway 210 checks whether the source address of the packet is the public IP band and the interface IP band of the gateway.

Accordingly, when the sender address of the packet is the public IP and the interface IP band managed by the gateway, the gateway 210 immediately performs packet routing (S406).

By the way, if the source address of the packet is the public IP band and the interface IP band managed by the gateway, packet routing is immediately performed (S406), but the source address of the packet is not the public IP or the public IP address, but the gateway is If it is not the interface IP band to be managed, the gateway 210 sends outbound packets destined for the Internet to allow a terminal having an IP address of a previous network to communicate with a terminal on the Internet using an IP band different from its own. The source address of the terminal 220, that is, converts the IP address or private IP address of the previous network 220 into its own NAT public IP address, and performs packet routing with reference to the NAT public IP address (S405, S406).

When the packet is received, if the destination address of the packet exists in the ARP cache information, the gateway 210 directly forwards the packet to the corresponding interface (S403).

That is, when the terminal having the IP address of the previous network communicates while being in the same network as the terminal using a different IP band from its own IP gateway, the gateway 210 forwards the packet through the Proxy ARP response process (S306) of FIG. If the receiving terminal is present in the ARP cache information after receiving it, since the packet can be sent directly without routing the packet, NAT address translation is not performed. (S401 to S403).

In the embodiment of the present invention, a process of processing an inbound packet flow from the Internet 230 to the gateway 210 will be described with reference to the operation flowchart of FIG. 5.

First, when a packet is received, the gateway 210 checks whether a destination address of the received packet exists in the NAT address translation table (S501).

Accordingly, when the destination address of the packet exists in the NAT address translation table, the gateway 210 converts the destination address of the packet into an existing IP address, that is, the IP address of the previous network of the terminal, and transmits the packet to the final destination terminal 220. In order to find out the MAC address of the terminal 220 by transmitting an ARP request message (S502, S503).

Here, the target IP address of the ARP request is the IP address of the previous network of the terminal extracted from the NAT address translation table.

Thereafter, the gateway 210 transmits the packet transmitted from the Internet 230 to the terminal 220.

As described in detail above, the present invention has an effect of providing convenience to a user by enabling communication and internet access between various terminals in the network without changing any existing network settings of the terminals in the network.

In particular, when the present invention is applied to the home network field, IP multicast and DNS services can be used without restriction in the network serviced by the gateway, thereby satisfying the basic requirements of middleware (eg, UPnP) gateways in the home network field. It can be used as a vendor specific extension function that enables communication and internet access between terminals in a network without changing existing network settings of terminals in the network.

In other words, the conventional technology applying the Mobile IP technology requires the terminal to be equipped with a technology called a home agent in the gateway of the network to which the terminal originally belongs so that the terminal can freely access any network on the Internet while maintaining its IP. The foreign agent should be equipped with a gateway of the current network. However, if the present invention is applied, communication and internet access with various types of terminals in the current network belong to the terminal regardless of the gateway implementation of the network to which the terminal originally belongs. Make it possible.

Claims (8)

In the gateway system for communication between the terminal and the Internet connection of the terminal, Means for transmitting a proxy ARP response message to the terminal when an ARP request is received from a terminal having an IP address of a previous network; And a means for performing packet routing with reference to ARP cache information for communication between a terminal having an IP address of a previous network and a terminal having a different IP band from the terminal. The method of claim 1, wherein the proxy ARP response is And if the target IP at the terminal does not match its own IP and the target IP does not exist in the ARP cache table. The method of claim 1, wherein the ARP cache information is Gateway system characterized in that the automatic discovery of the terminal in the network by the UPnP broadcast mechanism to obtain. The apparatus of claim 1, wherein the means for performing packet routing is For outbound packets, if the target address does not exist in the ARP cache table, and the source address of the packet is also not a public IP or a public IP address but is not the interface IP band governed by the gateway, the source address is converted to a NAT public IP. , And configure the target address to be converted to an existing IP address when the target address exists in the ARP cache table for inbound packets. The gateway system according to claim 4, wherein the existing IP address is an IP address or a private IP address of a previous network of the terminal. In the packet processing method of the gateway system for the communication between the terminal and the Internet connection of the terminal, When the ARP request is received from the terminal having the IP address of the previous network, if the target IP does not match its IP and the target IP does not exist in the ARP cache table, transmitting a proxy ARP response message to the terminal; When an outbound packet is received from the terminal receiving the proxy ARP response message to the terminal in another IP band, the target address does not exist in the ARP cache table with reference to the ARP cache information, and the source address of the packet is not a public IP. Performing packet routing by translating a source address into a NAT public IP when the gateway is not in an interface IP band managed by the gateway; When an inbound packet to the terminal is received from the terminal in a different IP band from the terminal, if the destination address of the packet exists in the ARP cache table with reference to ARP cache information, the destination address of the packet is stored in the existing terminal of the terminal. Transmitting the packet to the terminal by converting to an IP address, the packet processing method of the gateway system. 7. The method of claim 6, wherein executing packet routing is If the destination address exists in the ARP cache table, packet forwarding is performed to the corresponding interface. If the destination address does not exist in the ARP cache table but the packet source address is a public IP, the packet processing method of the gateway system comprising the step of performing packet routing without NAT address translation. The method of claim 6, wherein the existing IP address of the terminal is an IP address or a private IP of the previous network of the terminal.