KR100545586B1 - Dual stack transition mechanism router and method for cache table - Google Patents

Abstract

The system to which the dual stack switching mechanism router according to the present invention can minimize the communication short circuit caused by the inaccuracy of the cache table and the size of the cache table is located at the boundary of the IPv6 network, and responds to the IPv4 address in response to the IPv6 host address request message. Sends an IPv4 packet and a tunnel packet containing its IPv6 address by using an address assignment server that allocates the host to the host, an IPv4 address allocated from the address assignment server, and sends an address return message for returning the assigned IPv4 address. Router that sends IPv6 host and IP4 packet included in tunnel packet to IPv4 host to which IPv6 host wants to communicate, and deletes IPv6 address and IPv4 address pair of IPv6 host set in cache table upon receipt of address return message. It includes.

Description

Dual Stack Transition Mechanisms How to Manage Routers and Cache Tables {DUAL STACK TRANSITION MECHANISM ROUTER AND METHOD FOR CACHE TABLE}

1 is a block diagram illustrating a system for describing a dual stack switching mechanism router according to the present invention;

2 is a system for explaining the operation of the router in the system for managing the IPv4 address assigned to the host located in the IPv6 network of the present invention,

3 is a flowchart illustrating an operation process of a system for managing an IPv4 address assigned to a host located in an IPv6 network according to the present invention;

4 is a diagram illustrating a process of processing a tunnel packet received from an IPv6 host by a router according to the present invention;

5 is a diagram illustrating a process of processing an address return message received from an IPv6 host by a router according to the present invention;

6 is a flowchart illustrating a process of processing a UDPv6 message according to the present invention.

<Description of the code | symbol about the principal part of drawing>

100: IPv6 network 110: IPv6 host

120: address allocation server 142: IPv6 stack

144: IPv4 stack 146: protocol processing table

148: cache table 150: router

200: IPv4 network 210: IPv4 host

The present invention relates to address management between an IPv6 network and an IPv4 network, and more particularly, to a dual stack switching mechanism router and a cache table management method for managing a cache table by using an address return message and a timer received from an IPv6 host in an IPv6 network. will be.

Typical Dual Stack Translation Mechanism In a network environment, an IPv6 host obtains an IPv4 address dynamically through the DSTM server only when it needs to communicate with an IPv4 host and returns the address assigned to the DSTM server through a “RELEASE” message when the communication is terminated. . An IPv6 host that obtains an IPv4 address to communicate with an IPv4 host generates IPv4 packets and encapsulates them into IPv6 packets, referred to as 4 over 6 tunneling. These 4 misleading 6 tunnel packets are sent to the dual stack translation mechanism router.

Receiving the 4 over 6 tunnel packet, the DSTM TEP removes the encapsulation header to recover the IPv4 packet, and retrieves the IPv4 address-IPv6 address information pair of the source IPv6 host of the tunnel packet from the cache table. If the IPv4 address-IPv6 address information pair does not exist in the cache table, DSTM TEP saves the IPv4 address-IPv6 address information pair in the cache table and starts a valid timer for the corresponding item. If a pair is present, the timer for that item is initialized to extend the time it is kept in the cache. The DSTM TEP also sends the recovered IPv4 packet to the IPv4 host with which the IPv6 host wishes to communicate.

Conversely, when the DSTM TEP receives a packet sent from an IPv4 host, it retrieves the IPv6 address information corresponding to the packet's destination IPv4 address from the cache table, uses the retrieved address as the destination address, and sets the DSTM TEP's own IPv6 address as the source address. 4over6 encapsulation header is added to the IPv4 packet and delivered to the IPv6 host. If the DSTM TEP cannot find the IPv6 address information corresponding to the destination IPv4 in the cache table, the packet is discarded because it cannot be delivered. Therefore, the accuracy of cache table management in DSTM TEP is very important.

In general, the DSTM network allocates and releases an IPv4 address through an address request (REQUEST) message and an address return (RELEASE) message between an IPv6 host and a DSTM server.

In this way, the IPv6 host is assigned an IPv4 address only when communication with the IPv4 host is required, and when the IPv6 host is not needed, the IPv6 host returns an assigned IPv4 address to increase the utilization of the insufficient IPv4 address. On the other hand, because cache table management in DSTM TEP is implemented based only on the timer and the packet actually delivered, there is a case that the end-to-end terminal's IPv4 address usage status is not properly reflected in the cache table in the actual communication environment. As a result, there is a problem in that valid communication connections of end-to-end terminals are frequently shorted.

In particular, the cache table management by the timer has a problem in that valid communication connections are frequently shorted when the timer value is small, and the size of the cache table increases because it maintains invalid address information in the cache table for a long time when the timer value is large. do. The increase of the cache table size causes a problem that the cache table search time and load of the DSTM TEP are increased.

In this case, the communication short-circuit problem is frequently generated in a connection where the end-to-end terminal user has a long connection holding time such as telnet or a messenger but does not have much communication.

Summary of the Invention An object of the present invention is to solve such a problem of the prior art, and by managing address information pairs stored in a cache table using an address return message and a timer from an IPv6 host in an IPv6 network, a communication short circuit due to inaccuracy of the cache table. And to provide a dual stack switching mechanism router and cache table management method that can minimize the size of the cache table.

In order to achieve the above object, the present invention provides a system for managing an IPv4 address assigned to a host located in an IPv6 network, which is located at a boundary of the IPv6 network and corresponds to an address request message of the IPv6 host. An address allocation server for allocating the host to the host, an IPv4 packet and a tunnel packet including its own IPv6 address by using an IPv4 address assigned to the address allocation server, and returning an address for returning the allocated IPv4 address An IPv6 host that sends a message and an IP4 packet included in the tunnel packet to an IPv4 host to which the IPv6 host wants to communicate, and an IPv6 address of the IPv6 host set in a cache table upon receipt of the address return message; Routers that delete IPv4 address information pairs.

 In addition, the present invention provides an address management method of a system for managing an IPv4 address assigned to a host located in an IPv6 network, the method comprising: allocating an IPv4 address to the IPv6 host according to an IPv4 address request of the IPv6 host; Transmitting the tunnel packet including the IPv4 packet and its IPv6 address to the router using the assigned IPv4 address, and receives the tunnel packet from the IPv6 host to receive the IPv6 address and IPv4 packet in the tunnel header of the tunnel packet Extracting and determining whether information corresponding to the IPv4 address and the IPv6 address information pair included in the header of the IPv4 packet exists in the cache table; and as a result of the determination, the address information pair does not exist in the cache table. Register the address information pair in a cache table and activate a timer function corresponding to the address information pair. Transmitting the IPv4 packet to an IPv4 host, checking whether the router receives an address return message to an IPv6 host after transmitting the IPv4 packet, and as a result of the checking, the address return message is received. Deleting the address information pair from the cache table.

There may be a plurality of embodiments of the present invention, and a preferred embodiment will be described in detail below with reference to the accompanying drawings. Those skilled in the art will be able to understand the object, features, and advantages of the present invention through this embodiment.

1 is a block diagram illustrating a system for describing a dual stack switching mechanism router according to the present invention.

As shown therein, a system for managing an IPv4 address assigned to a host located in an IPv6 network includes an IPv6 network 100, a router 150, and an IPv4 network 200.

The IPv6 network 100 includes an IPv6 host 110 and an address assignment server 120, and the address assignment server 120 assigns an IPv6 address 110 to an IPv6 host 110 in response to an address request message of the IPv6 host 110. ) And retrieves the assigned IPv4 address by receiving the address return message of the IPv4 host 110. In particular, the address assignment server 120 is a DHCPv6 server that dynamically allocates an IPv4 address in response to the address request message of the IPv6 host 110.

The IPv6 host 110 transmits an IPv4 packet and a tunnel packet including its IPv6 address by using the IPv4 address assigned to the address assignment server 120 and sends an address return message for returning the assigned IPv4 address. It transmits to 120 and the router 150.

The tunnel packet transmitted from the IPv6 host 110 includes the IPv6 address of the router 150 as the sender address by using the IPv6 address of the IPv6 host 110 in an IPv4 packet including the IPv4 address and data allocated by the address assignment server 120. Is a packet with a 4 over 6 tunnel header added as a destination address.

The address return message includes message data for returning an IPv4 address allocated by the address assignment server 120, IPv6 address information of the IPv6 host 110, and UDPv6 information. The address return message is transmitted to the address assignment server 120 and the router 150 using the UDPv6 protocol.

There are a plurality of IPv4 and IPv6 hosts in the IPv4 network 200 and the IPv6 network 100, respectively. In the present invention, only one host, the IPv6 host 110 and the IPv4 host 210, is illustrated.

The router 150 is a dual stack switching mechanism router according to the present invention, which includes an IPv6 stack 142, an IPv4 stack 144, a protocol processing table 146, and a cache table 148, and receives from the IPv6 host 110. The IP4 packet included in the processed tunnel packet is transmitted to the IPv4 host to which the IPv6 host wants to communicate, and upon receipt of the address return message, the IPv6 address and the IPv4 address information pair set in the cache table 148 are deleted.

The cache table 148 stores IPv4 addresses assigned to the IPv6 hosts 110 and IPv6 address information pairs of respective IPv6 hosts, and a timer is set in each information pair.

The IPv6 stack 142 receives the tunnel packet transmitted from the IPv6 host 110 and uses the handler function included in the protocol processing table 146 to transfer the IPv4 packet included in the tunnel packet through the IPv4 stack 144 to the IPv4 stack 144. It transmits to the IPv4 host 210 of the network 200. In addition, the IPv6 stack 142 receives the address return message transmitted from the IPv6 host 110, and uses IPv6 address information of the IPv6 host 110 included in the address return message by using a handler registered in the protocol processing table 146. The searched address information pair is searched in the cache table 148 and then the searched address information pair is removed.

The handler registered in the protocol processing table 146 receives the tunnel packet from the IPv6 host, extracts the IPv6 address and the IPv4 packet from the tunnel header of the tunnel packet, and corresponds to the IPv4 address and the IPv6 address information included in the header of the IPv4 packet. 4 ovo 6 tunnel handler (tep_rcv) for resetting the timer set for the pair of information or storing the address information in the cache table 148 and then transmitting the IPv4 packet to the IPv4 host 210 through the IPv4 stack 144; In response to receiving the address return message from the IPv6 host 110, a message processing handler (udpv6_hook_rcv) that searches for and removes an address information pair corresponding to the IPv6 address included in the address return message from the cache table, and uses the TCP protocol. Tcpv6_rcv for processing the transmitted packets, and UDPv6 handler for processing general UDPv6 messages transmitted from the IPv6 host 110 using the UDPv6 protocol. Include.

An operation process of a system for managing an IPv4 address assigned to a host located in an IPv6 network having the above structure will be described with reference to FIGS. 2 to 3.

2 is a system for explaining an operation process of a router in a system for managing an IPv4 address assigned to a host located in an IPv6 network of the present invention, and FIG. 3 shows an IPv4 address assigned to a host located in an IPv6 network according to the present invention. It is a flowchart showing the operation process of the managing system.

As shown in Figs. 2 to 3, the IPv6 host 110 has only an IPv6 address (for example, 11) and communicates with the IPv4 host 210 of the IPv4 network 200 without being assigned an IPv4 address. In order to transmit the IPv4 address request message for the IPv4 address assignment to the address assignment server 120, and receives an IPv4 address (for example, 178) from the DSTM server 120 (S300). The IPv6 host 110 assigned the IPv4 address generates an IPv4 packet having the IPv4 address 178 as the sender address and the IPv4 address of the IPv4 host 210 as the destination address, and the IPv6 address of the IPv6 host 110 in the IPv4 packet. After generating the tunnel packet to which the 4 over 6 tunnel header which added "11" as a sender address and the IPv6 address of the router 150 as a destination address is generated, it transmits it to the router 150 (S302).

Receiving this encapsulated packet, the router 150 searches the cache table 148 with the sender IPv6 address of the tunnel header and the sender IPv4 address information pair of the IPv4 packet header. If the address information pair is present in the cache table 148, the timer corresponding to the address information pair is reset, and if not, the address information included in the tunnel packet is stored in the cache table 148 (S302).

The router 150 transmits the restored IPv4 packet to the IPv4 host 210 of the IPv4 network 200 through a general routing process of the IPv4 communication protocol (S302).

The IPv4 host 210 receiving the IPv4 packet recognizes that the IPv4 address of the IPv6 host 110 is "178" based on the received IPv4 packet, and sends the destination address to "178" when transmitting information to the IPv6 host 110. And generate an IPv4 packet. The generated IPv4 packet is transmitted to the router 150 by a general routing process. The router 150 retrieves “11” which is IPv6 address information corresponding to the destination address information of the IPv4 packet received from the IPv4 host 210 through the search of the cache table 148 (S304).

In this case, since the router 150 previously stored the address information in the cache table 148 while processing the packet transmitted from the IPv6 host 110 to the IPv4 host 210, the IPv6 address corresponding to the destination address of the IPv4 packet is stored. You can search for "11". The router 150 adds a 4 over 6 encapsulation header having the IPv6 address retrieved from the IPv4 host 210 as the destination address and the router 150 own IPv6 address as the destination address. The host 110 transmits the data to the host 110 (S304).

Through the above process, communication between the IPv6 host 110 and the IPv4 host 210 is made.

Subsequently, after the IPv4 host 210 terminates communication, the IPv6 host 110 transmits an RELEASE message to the address assignment server 120 to return the IPv4 address allocated from the address assignment server 120. At this time, the IPv6 host 110 transmits an IPv4 address return message to the address assignment server 120 and also to the router 150.

The router 150 deletes address information and related information corresponding to the address return message from the cache table 148. In other words, the IPv6 address and the IPv4 address information pair "11, 178" set in the cache table 148 are deleted (S308).

Step S302, in which the router 150 processes the tunnel packet transmitted from the IPv6 host 110, will be described with reference to FIG. 4. 4 is a diagram illustrating a process of processing a tunnel packet received from an IPv6 host by a router according to the present invention.

As shown therein, the IPv6 stack 142 of the router 150 receiving the tunnel packet from the IPv6 host 110 of the IPv6 network 100 checks that the destination address of the IPv6 header is itself, and then loads the IPv4 packet in the data. Packet is provided to the 4 ovo 6 tunnel handler (tep_rcv) registered in the protocol processing table 146 of the router 150. The 4 ovo 6 tunnel handler (tep_rcv) restores the IPv4 packet and then returns the IPv6 address of the sender. The cache table 148 is searched as a sender IPv4 address information pair of the IPv4 packet header.

4 The misleading 6 tunnel handler tep_rcv registers the address information pair in the cache table 148 when the address information pair included in the tunnel packet received as a result of the search of the cache table 148 does not exist in the cache table 148. The timer function is driven and the timer is reset when present in the cache table 148.

Thereafter, the 4 misleading 6 tunnel handler tep_rcv forwards the restored IPv4 packet to the IPv4 stack 144, and the IPv4 stack 144 transmits the IPv4 packet to the IPv4 host 210 through a general routing process.

Operation S306, in which the router 150 processes the address return message received from the IPv6 host 110, will be described with reference to FIG. 5. 5 is a diagram illustrating a process of a router processing an address return message received from an IPv6 host according to the present invention.

As shown in FIG. 5, the IPv6 host 110 transmits an address return message to the router 150 using the UDPv6 protocol, and since the address return message uses the UDPv6 protocol, the router 150 uses the IPv6 stack ( The address return message is processed using the address return message handler udpv6_hook_rcv registered in the protocol processing table 146 of 142. At this time, the router 150 backs up the UDPv6 message handler which processes the general UDPv6 message.

When the IPv6 stack 142 of the router 150 receives the UDPv6 message, the router 150 delivers the UDPv6 message to the address return message handler udpv6_hook_rcv registered in the protocol processing table 148. The received address return message handler (udpv6_hook_rcv) provides the UDPv6 message handler when the message data contained in the packet is a normal UDPv6 message, and the extracted IPv6 address information when the message data includes the address return information. The cache table 148 is searched to delete address pairs corresponding to the IPv6 address information from the cache table 148.

The processing of the address return message as described above will be described below with reference to FIG. 6. 6 is a flowchart illustrating a process of processing a UDPv6 message according to the present invention.

As shown in FIG. 6, the router 150 receiving the UDPv6 message from the IPv6 host 110 determines whether the UDPv6 message is an address return message (S400 and S402). As a result of the determination in step S402, when the UDPv6 message is not the address return message, the UDPv6 message is processed using the UDPv6 message handler backed up to the router 150, and the protocol of the router 150 when the UDPv6 message is the address return message. Using the address return message processing handler (udpv6_hook_rcv) registered in the processing table 146, the address information pair corresponding to the IPv4 address information allocated to the IPv6 host 110 that delivered the address return message is deleted from the cache table 148. (S406).

Thereafter, it is determined whether the address of the address assignment server 120 included in the UDPv6 message received from the IPv6 host 110 is the same as the address of the router 150 (S408).

As a result of the determination in step S408, the router 150 forwards the packet to the backed up UDPv6 message handler when the address of the address assignment server 120 included in the UDPv6 message is the same as the address of the router 150; Discard the packet (S410).

As described above, the present invention stores only the address information pair currently being communicated in the cache table by deleting the IPv6 address and the IPv4 address information pair of the IPv6 hosts that have sent the address return message using the address return message processing handler. This solves the short circuit problem between hosts, which occurs as the timer setting time decreases.

In addition, since the present invention stores only the address information pairs currently being communicated in the cache table, the timer value can be increased without expanding the cache table.

Claims (9)

In a system for managing an IPv4 address assigned to a host located in an IPv6 network, An address assignment server located at a boundary of the IPv6 network and assigning an IPv4 address to the host in response to an address request message of the IPv6 host; An IPv6 host that transmits an IPv4 packet and a tunnel packet including its IPv6 address using an IPv4 address assigned to the address assignment server, and sends an address return message for returning the allocated IPv4 address; A router for transmitting the IP4 packet included in the tunnel packet to an IPv4 host to which the IPv6 host intends to communicate, and deleting the IPv6 address and IPv4 address information pair of the IPv6 host set in the cache table upon receipt of the address return message; Including dual stack switching mechanism router. The method of claim 1, The router, Receiving a tunnel packet from the IPv6 host, extracting an IPv6 address and an IPv4 packet from the tunnel header of the tunnel packet, and resetting the timer function corresponding to the IPv4 address and IPv6 address information pair included in the header of the IPv4 packet; A 4 oboe 6 tunnel handler which stores the pair of address information in a cache table, And a message processing handler for retrieving and removing from the cache table an address information pair corresponding to an IPv6 address included in the address return message when the address return message is received from the IPv6 host. The method of claim 2, And the address return message is transmitted to the router using a UDPv6 protocol. The method of claim 1, And the address assignment server retrieves the IPv4 address assigned to the IPv6 host upon receipt of an address return message from the IPv6 host. The method of claim 1, And the address assignment server is a DHCPv6 server that dynamically assigns an IPv4 address to the IPv6 host. In the address management method of the management system in the IPv4 address assigned to the host located in the IPv6 network, Allocating an IPv4 address to the IPv6 host according to an IPv4 address request of the IPv6 host; The IPv6 host transmits the IPv4 packet and the tunnel packet including its IPv6 address to the router using the assigned IPv4 address; Receiving a tunnel packet from the IPv6 host, extracting an IPv6 address and an IPv4 packet from the tunnel header of the tunnel packet, and whether information corresponding to the IPv4 address and the IPv6 address information pair included in the header of the IPv4 packet exists in the cache table Determining whether or not, If the address information pair does not exist in the cache table, registering the address information pair in the cache table, activating a timer function corresponding to the address information pair, and then transmitting the IPv4 packet to an IPv4 host. Wow, Checking, by the router, whether to receive an address return message from an IPv6 host after transmitting the IPv4 packet; And deleting the address information pair from the cache table when the address return message is received as a result of the check. The method of claim 6, And the cache table management method of the dual stack switching mechanism router that resets a timer function corresponding to the information when the information corresponding to the address information pair exists in the cache table. The method of claim 6, And the address return message is transmitted to the router using a UDPv6 protocol. The method of claim 6, The IPv6 host, the cache table management method of a dual stack switching mechanism router that is assigned the IPv4 address from a DHCPv6 server.

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