JP2005223449A - Router and static domain name routing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a router and a static domain name routing capable of more properly carrying out routing by using a routing table stored in a volatile memory. <P>SOLUTION: The router includes: a packet collection section 24 for collecting IP packets with collected addresses from a terminal 4; a packet transfer section 30 for transferring the IP packets to a corresponding gateway corresponding to the collected address by referencing the routing table 15; a reverse resolution inquiry section 26 for collecting a reply domain name corresponding to the collected address from a DNS server when no corresponding gateway is searched; a gateway searching section 28 for searching the reply gateway corresponding to the reply domain name by referencing a domain name routing table 17; and a routing table update section 29 for recording the collected address to the routing table 15 by correlating the collected address with the reply gateway. The router 1 can transfer the IP packets to a more proper gateway even when no corresponding gateway is searched from the routing table 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a router and static domain name routing, and more particularly to a router and static domain name routing used when routing using a domain name.

  When an IP packet output from a terminal is transmitted to a destination computer via the Internet, routing is performed to find a route through which the IP packet can be transmitted more efficiently. This routing is executed by a router that constitutes the Internet. That is, the router extracts an IP address from the IP packet, searches for a route (gateway) corresponding to the IP address from a routing table held in the own device, and sends the IP packet to the searched gateway. .

  Furthermore, domain name routing is known in which a route is determined using a domain name of a destination to be accessed. The router that performs the domain name routing statically records the route (gateway) in association with the domain name. The router further has a proxy DNS server function that inquires / responds to the DNS server in response to an inquiry about the domain name transmitted from the terminal, or relays the terminal and the DNS server.

  In domain name routing, when a terminal wishes to access another computer by specifying a domain name, it creates an inquiry packet indicating the domain name and transmits the inquiry packet to a DNS server via a router. Upon receiving the inquiry packet, the DNS server returns a response packet indicating the IP address corresponding to the domain name to the terminal via the router. At this time, the router temporarily records (caches) the domain name indicated by the inquiry packet in association with the IP address indicated by the response packet.

  When the terminal receives the response packet, the terminal temporarily records the IP address indicated by the response packet in association with the domain name. When transmitting information to the computer indicated by the domain name, the terminal 4 creates an IP packet using the temporarily recorded IP address and transmits it to the router 1. The terminal does not query the DNS server for the IP address for the domain name until the temporarily recorded domain name / IP address pair disappears.

  Therefore, the router cannot recognize that the IP packet is an access to the routed domain name when the cached routing table is lost by turning off the power, etc. To send. Thus, the router may not be able to perform proper routing when the terminal table temporarily stores the IP address for the domain name and the routing table is lost.

  The router can also store the routing table in a non-volatile memory so that routing after power off / on operates normally. However, nonvolatile memories are generally not suitable for recording a routing table because they are expensive and operate slowly. The routing table is desirably recorded in the volatile memory, and it is desired to perform more appropriate routing using the routing table stored in the volatile memory.

  Japanese Patent Laid-Open No. 2002-217950 discloses an information processing method capable of supporting the movement of a node. In the information processing method, the router receives a data packet transmitted from a node located in the same domain, and extracts the lower 64 bits of the IPv6 address described in the end point address field of the header of the data packet. . Next, the router refers to the routing table and checks whether there is a host entry related to the interface ID described in the extracted lower 64 bits. Next, when it is determined that there is a host entry, the data packet is transmitted according to the host entry.

  Japanese Patent Application Laid-Open No. 11-284667 discloses a multimedia communication network system that can make a call without a sense of incongruity even when performing voice communication. In the multimedia communication network system, an IP address is assigned to each terminal device at each office, and a multimedia domain name is inserted in the lowest layer, in which the telephone number of the terminal device is inserted instead of the user name. Further, for each local network system, in addition to the DNS server function, the router device is provided with a multimedia communication control function and its multimedia database, and the multimedia domain name and IP of each terminal device are stored in the multimedia database. The correspondence with the address is stored. When a signal including a multimedia domain name arrives from a terminal device, the signal is transferred to a terminal device having a corresponding IP address based on the multimedia database.

  Japanese Patent Application Laid-Open No. 11-340984 discloses an IP address search system that reduces the traffic of a segment in which a DNS server is present and answers a DNS response to a client more quickly and reliably. In the IP address search system, in response to a DNS request from a client, the router stores the host name and IP address from the upper DNS server in the HTTP table by the update processing unit via the department DNS server, and stores them in the client. Forward. The client sends the proxy. com. Next time, when the client sends a DNS request to the department DNS server in order to connect to the HTTP server, the router searches the HOSTS table, and since there is an IP address corresponding to the host name, the DNS request is sent to the department DNS server. Replies directly to the client without forwarding to the server.

  Japanese Patent Application Publication No. 2002-524979 discloses an apparatus for transparently processing DNS traffic, which reduces a waiting time in a DNS response and reduces network traffic. An updated router that recognizes that the information consists of DNS traffic, parses the information, caches the address information (if any), and then retransmits the desired information to the name service client Is provided. Thus, when another request for the same address information is forwarded to the router, the router can provide a response to the requester rather than forwarding the request to a distant name server. In this way, the router interrupts DNS traffic and caches DNS information so that clients utilizing different name servers can benefit from the cached information.

  JP 2002-525944 discloses a storage device attached to a storage router in a fiber channel network to determine the physical address of the storage router's arbitration loop using the fully qualified domain name of the storage router. A method and system for discovering the location of is posted. In the method and system, a domain name query is sent from a host computer to a domain name server over a network. The domain name server responds with the IP address of the storage router. The host computer then sends an address resolution protocol request including the IP address over the network. The storage router responds with the node name. The host computer then sends an FCP request containing the node name of the storage router over the network. The storage router responds with its AL_PA. At this time, the host computer may use various standard queries.

JP 2002-217950 A JP-A-11-284667 JP 11-340984 A JP-T-2002-524979 JP-T-2002-525944

An object of the present invention is to provide a router that performs more appropriate routing using a routing table stored in a volatile memory and static domain name routing.
Another object of the present invention is to provide a router and a static domain name routing that perform more appropriate routing by using a routing table stored in a volatile memory and reduce traffic between the router and the DNS server. It is in.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in [Embodiments of the Invention] in parentheses. These numbers and symbols are added to clarify the correspondence between the description of [Claims] and the description of [Mode for carrying out the invention], and are described in [Claims]. It should not be used to interpret the technical scope of the invention.

  The router (1) according to the present invention refers to a packet collection unit (24) that collects data packets having collection addresses from a terminal (4) and a routing table (15) that associates multiple addresses with multiple gateways. A packet transfer unit (30) for transferring a data packet to the corresponding gateway corresponding to the collection address, and a reply domain corresponding to the collection address from the DNS server (5) when the corresponding gateway is not searched from the routing table (15) A reverse lookup inquiry unit (26) for collecting names and a domain name routing table (17) for associating a plurality of domain names with a plurality of gateways to search for an answer gateway corresponding to the answer domain name from among the plurality of gateways Search part And 28), the routing table (15), and a routing table update unit (29) for recording in association with the collection address to answer the gateway.

  That is, the data packet is transferred to the answer gateway when the corresponding gateway is not retrieved from the routing table (15). The router (1) can transfer the data packet to a more appropriate gateway even when the corresponding gateway is not retrieved from the routing table (15). As a result, when the routing table (15) is stored in the volatile memory, the router (1) can transfer the data packet to a more appropriate gateway even when the routing table (15) is lost due to restart. Can do.

  The router (1) according to the present invention further includes a DNS table update unit (27) that records a collection address and a reply domain name in association with each other in a DNS table (16) that associates a plurality of addresses with a plurality of domain names, and a DNS table. Referring to (16), a domain name search unit (25) for searching a search domain name corresponding to the collection address from a plurality of domain names is provided. When the search domain name is searched from the DNS table (16), the gateway search unit (28) searches the search gateway corresponding to the search domain name from the plurality of gateways by referring to the domain name routing table (17). To do. The routing table update unit (29) records the collected address in association with the search gateway in the routing table (15).

  That is, the data packet is transferred to the search gateway when the search domain name is searched from the DNS table (16). The router (1) does not need to communicate with the DNS server (5) when the search domain name is retrieved from the DNS table (16). Therefore, the router (1) can reduce traffic with the DNS server (5).

  The router (1) according to the present invention further includes a domain name collection unit (20) that collects collection domain names from the terminal (4), and an inquiry unit that collects response addresses corresponding to the collection domain names from the DNS server (5). (22) and an address reply unit (23) for replying the reply address to the terminal (4). The gateway search unit (28) searches the collection gateway corresponding to the collection domain name from the plurality of gateways with reference to the domain name routing table (17). At this time, it is preferable that the routing table update unit (29) records the answer address in the routing table (15) in association with the collection gateway.

  The router (1) according to the present invention further includes an address search unit (21) that searches the DNS table (16) for a search address corresponding to the collection domain name from a plurality of addresses. When the search address is not searched from the DNS table (16), the DNS table update unit (27) records the answer address and the collection domain name in association with each other in the DNS table (16). When the search address is searched from the DNS table (16), the routing table update unit (29) records the search address in the routing table (15) in association with the collection gateway. At this time, the router (1) does not need to communicate with the DNS server (5) when the search domain name is searched from the DNS table (16). Therefore, the router (1) can reduce traffic with the DNS server (5).

  The static domain name routing according to the present invention is executed by the router (1) and includes a step (S11) of collecting data packets having collection addresses from the terminal (4), and a routing table (15) for associating the plurality of addresses with a plurality of gateways. Referring to the step of transferring the data packet to the corresponding gateway corresponding to the collection address among the plurality of gateways (S20), and when the corresponding gateway is not searched from the routing table (15), the collection address from the DNS server (5) Collecting the response domain names corresponding to the (S14, S15), and referring to the domain name routing table (17) for associating the multiple domain names with the multiple gateways, the response domain names from the multiple gateways are supported. A step (S17) to find answers gateway that, in the routing table (15), and a routing step (S18) for recording in association with the collection address to answer the gateway.

  That is, the data packet is transferred to the answer gateway when the corresponding gateway is not retrieved from the routing table (15). The router (1) can transfer the data packet to a more appropriate gateway even when the corresponding gateway is not retrieved from the routing table (15). As a result, when the routing table (15) is stored in the volatile memory, the router (1) can transfer the data packet to a more appropriate gateway even when the routing table (15) is lost due to restart. Can do.

  The static domain name routing according to the present invention further refers to a DNS table (16) that associates a plurality of addresses with a plurality of domain names, and searches for a search domain name corresponding to the collected address from among the plurality of domain names (S13). ), And when a search domain name is searched from the DNS table (16), a search gateway corresponding to the search domain name is searched from the plurality of gateways by referring to the domain name routing table (17) (S17). And a step of recording the collection address in the routing table (15) in association with the search gateway (S18), and when the search domain name is not searched from the DNS table (16), the collected address and reply to the DNS table (16) Map to domain name And a step (S16) for recording.

  That is, the data packet is transferred to the search gateway when the search domain name is searched from the DNS table (16). The router (1) does not need to communicate with the DNS server (5) when the search domain name is retrieved from the DNS table (16). Therefore, the router (1) can reduce traffic with the DNS server (5).

  The static domain name routing according to the present invention further includes a step (S1) of collecting the collection domain name from the terminal (4), and a step of collecting response addresses corresponding to the collection domain name from the DNS server (5) (S3, S4). ), Returning the reply address to the terminal (4) (S9), and referring to the domain name routing table (17), searching the collection gateway corresponding to the collection domain name from among the plurality of gateways (S6) And a step (S7) of recording the reply address in association with the collection gateway in the routing table (15).

  The static domain name routing according to the present invention further includes a step (S2) of searching a search address corresponding to the collection domain name from a plurality of addresses with reference to the DNS table (16), and a search from the DNS table (16). When the address is retrieved, a step (S7) of recording the retrieval address in association with the collection gateway in the routing table (15), and when the retrieval address is not retrieved from the DNS table (16), the reply address and the collection domain A step (S5) of associating names with each other and recording them in the DNS table (16). At this time, the router (1) does not need to communicate with the DNS server (5) when the search domain name is searched from the DNS table (16). Therefore, the router (1) can reduce traffic with the DNS server (5).

  The router and static domain name routing according to the present invention can perform more appropriate routing by using a routing table stored in a volatile memory.

  An embodiment of a router according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the router 1 is applied to the Internet 2 that connects a plurality of information processing devices (computers) so that information can be transmitted bidirectionally. The Internet 2 is formed from a plurality of networks connected to each other, and includes a router 1 and a DNS server 5. The router 1 is connected to a terminal 4 that is a computer via a network 3. The router 1 is further connected to a plurality of networks different from the network 3 via a plurality of gateways 6-1 to 6-n (n = 2, 3, 4,...).

  The DNS server 5 includes a database in which IP addresses of computers connected to the Internet 2 are associated with domain names. In response to the inquiry packet transmitted from the information processing apparatus or router, the DNS server 5 creates a response packet and returns it to the information processing apparatus or router. The response packet indicates an IP address corresponding to the domain name when the inquiry packet indicates a domain name, and a domain name corresponding to the IP address when the inquiry packet indicates an IP address. Is shown.

  When there is information to be transmitted to another computer, the terminal 4 creates an IP packet and transmits it to the router 1. The IP packet is formed of a header and an information field. The header indicates an IP address indicating the destination of the destination computer, and the information field indicates the information to be transmitted. Further, when the terminal 4 wants to obtain an IP address from the domain name of the destination computer, the terminal 4 creates an inquiry packet indicating the domain name and sends it to the router 1 to inquire about the IP address. The terminal 4 further receives a response packet from the router 1 and temporarily records the IP address indicated by the response packet in association with the domain name. When transmitting information to the computer indicated by the domain name, the terminal 4 creates an IP packet using the temporarily recorded IP address and transmits it to the router 1.

  FIG. 2 shows the router 1 in detail. The router 1 includes a router body 11, a volatile memory 12, a nonvolatile memory 13, and a plurality of interfaces 14-1 to 14-n. The volatile memory 12 is a memory whose stored contents are lost when power supply from the power supply is stopped. The volatile memory 12 records a routing cache table 15 and a DNS cache table 16. The nonvolatile memory 13 is a memory in which stored contents are not lost even when the supply of power from the power supply is stopped. Examples of the nonvolatile memory 13 include a FLASH memory and a magnetic disk. The non-volatile memory 13 records a domain name routing table 17. The interface 14-i (i = 1, 2, 3,..., N) connects the router body 11 to the gateway 6-i.

  The router body 11 is a computer and executes an installed computer program. The router body 11 includes a domain name collection unit 20, an IP address search unit 21, an inquiry unit 22, an IP address return unit 23, an IP packet collection unit 24, a domain name search unit 25, a reverse inquiry unit 26, and DNS, which are computer programs. A table update unit 27, a gateway search unit 28, a routing table update unit 29, and an IP packet transfer unit 30 are installed.

  The domain name collection unit 20 collects inquiry packets from the terminal 4 via the network 3. The inquiry packet indicates the domain name indicating the destination of the computer that is the transmission destination of the information. The IP address search unit 21 searches the DNS cache table 16 for an IP address corresponding to the domain name indicated by the inquiry packet collected by the domain name collection unit 20.

  The inquiry unit 22 transfers the inquiry packet collected by the domain name collection unit 20 to the DNS server 5 when the IP address retrieval unit 21 does not retrieve an IP address. The inquiry unit 22 further receives a response packet returned from the DNS server 5 and acquires an IP address corresponding to the domain name indicated by the inquiry packet collected by the domain name collection unit 20 from the response packet.

  The IP address reply unit 23 creates a response packet indicating the IP address searched by the IP address search unit 21 and returns the response packet to the terminal 4 via the network 3. The IP address reply unit 23 forwards the response packet received by the inquiry unit 22 to the terminal 4 via the network 3.

  The IP packet collection unit 24 collects IP packets from the terminal 4 via the network 3. The IP packet indicates an IP address indicating a destination of a computer that is a transmission destination of information.

  The domain name search unit 25 searches the domain name corresponding to the IP address indicated by the IP packet collected by the IP packet collection unit 24 with reference to the DNS cache table 16. The reverse inquiry unit 26 creates an inquiry packet indicating the IP address indicated by the IP packet collected by the IP packet collection unit 24 when the domain name is not retrieved by the domain name retrieval unit 25, and the inquiry packet Is transmitted to the DNS server 5. The reverse inquiry unit 26 further receives the response packet returned from the DNS server 5 and acquires the domain name corresponding to the IP address indicated by the IP packet collected by the IP packet collection unit 24 from the response packet. .

  The DNS table update unit 27 records the domain name / IP address pair acquired from the DNS server 5 by the inquiry unit 22 in the DNS cache table 17. The DNS table updating unit 27 further records the domain name / IP address pair acquired from the DNS server 5 by the reverse inquiry unit 26 in the DNS cache table 17.

  The gateway search unit 28 refers to the domain name routing table 16 and searches for a gateway corresponding to the domain name collected by the domain name collection unit 20. Further, the gateway search unit 28 refers to the domain name routing table 16 to search for a gateway corresponding to the domain name collected by the domain name search unit 25. Further, the gateway search unit 28 refers to the domain name routing table 16 to search for a gateway corresponding to the domain name collected from the DNS server 5 by the reverse lookup inquiry unit 26.

  The routing table update unit 29 records the pair of the IP address and gateway searched by the gateway search unit 28 in the routing cache table 15. The IP packet transfer unit 30 refers to the routing cache table 15 and sends the IP packet to the gateway corresponding to the IP address indicated by the IP packet collected by the IP packet collection unit 20.

  FIG. 3 shows the routing cache table 15 in detail. The routing cache table 15 associates the gateway 32 with the IP address 31. An IP address 31 indicates the IP address of a computer connected to the Internet 2. The gateway 32 is a gateway that sends out an IP packet to be transmitted to the computer indicated by the IP address 31 among the gateways 6-1 to 6-n. The routing cache table 15 loses its stored contents when the supply of power from the power supply is stopped. The routing cache table 15 further records a default gateway. The default gateway does not lose the stored contents from the routing cache table 15 even when the supply of power from the power supply is stopped.

  FIG. 4 shows the domain name routing table 17. The domain name routing table 17 associates the gateway 42 with the domain name 41. A domain name 41 indicates the domain name of a computer connected to the Internet 2. The gateway 42 is a gateway that sends out an IP packet to be transmitted to the computer indicated by the domain name 41 among the gateways 6-1 to 6-n. The domain name routing table 17 does not lose its stored contents when the supply of power from the power supply is stopped.

  FIG. 5 shows the DNS cache table 16. The DNS cache table 16 associates the domain name 51 and the IP address 52 with each other. A domain name 51 indicates the domain name of a computer connected to the Internet 2. The IP address 52 indicates the IP address of the computer indicated by the domain name 51. The DNS cache table 16 loses its stored contents when the supply of power from the power supply is stopped.

  The static domain name routing according to the present invention is executed by the router 1 and includes an operation of returning an IP address corresponding to the domain name to the terminal 4 in response to an inquiry of the terminal 4 and an operation of routing an IP packet. .

  FIG. 6 shows an operation of returning an IP address corresponding to the domain name to the terminal 4 in response to the inquiry from the terminal 4. When the terminal 4 wants to access a partner whose domain name is known and whose IP address is unknown, the terminal 4 creates an inquiry packet indicating the domain name and transmits the inquiry packet to the router 1 (step S1). Upon receiving the inquiry packet, the router 1 refers to the DNS cache table 16 and searches for an IP address corresponding to the domain name indicated by the inquiry packet (step S2).

  When the domain name is not recorded in the DNS cache table 16 (step S2; no domain name), the router 1 transfers the inquiry packet to the DNS server 5 (step S3). Upon receiving the inquiry packet, the DNS server 5 returns a response packet indicating the IP address corresponding to the domain name to the router 1 in response to the inquiry from the terminal 4 (step S4). The router 1 associates the domain name indicated by the inquiry packet with the IP address indicated by the response packet and records it in the DNS cache table 17 (step S5).

  The router 1 refers to the domain name routing table 16 and searches for a gateway corresponding to the domain name searched from the DNS cache table 17, or searches for a gateway corresponding to the domain name indicated by the inquiry packet (step S6). ). The router 1 records the retrieved gateway in the routing cache table 15 in association with the IP address retrieved from the DNS cache table 17, or associates the retrieved gateway with the IP address indicated by the response packet in the routing cache. It records on the table 15 (step S7).

  When the gateway is not retrieved from the domain name routing table 16 (step S6; no domain name), the router 1 records the default gateway in the routing cache table 15 in association with the IP address retrieved from the DNS cache table 17. Alternatively, the default gateway is recorded in the routing cache table 15 in association with the IP address indicated by the response packet (step S8).

  The router 1 further transfers the response packet to the terminal 4 (step S9). When the terminal 4 receives the response packet, the terminal 4 temporarily records the IP address indicated by the response packet in association with the domain name. When transmitting information to the computer indicated by the domain name, the terminal 4 creates an IP packet using the temporarily recorded IP address and transmits it to the router 1.

  According to such an operation, the router 1 does not need to make an inquiry to the DNS server 5 when the DNS cache table 16 records an IP address corresponding to the domain name indicated by the inquiry packet. For this reason, the traffic between the router 1 and the DNS server 5 can be reduced.

  FIG. 7 shows an operation for routing an IP packet. When there is information to be transmitted to another computer, the terminal 4 creates an IP packet and sends it to the router 1 (step S11). The IP packet indicates an IP address indicating the destination of the destination computer and information to be transmitted. When receiving the IP packet, the router 1 searches the routing cache table 15 for a gateway corresponding to the IP address of the destination of the IP packet (step S12). When the gateway is not searched from the routing cache table 15 (step S12; no IP address), the router 1 searches the DNS cache table 16 for a domain name corresponding to the IP address indicated by the IP packet (step S13).

  When the domain name is not recorded in the DNS cache table 16 (step S13; no domain name), the router 1 creates an inquiry packet indicating the IP address, and transmits the inquiry packet to the DNS server 5. The domain name corresponding to the IP address is inquired (step S14). When receiving the inquiry packet, the DNS server 5 returns a response packet indicating the domain name corresponding to the IP address to the router 1 (step S15). The router 1 records the domain name indicated by the response packet in the DNS cache table 17 in association with the IP address indicated by the IP packet (step S16).

  The router 1 refers to the domain name routing table 16 and searches for a gateway corresponding to the domain name searched from the DNS cache table 17, or searches for a gateway corresponding to the domain name indicated by the response packet (step S17). ). When the gateway 1 is searched for from the domain name routing table 16 (step S17; with domain name), the router 1 records the searched gateway in the routing cache table 15 in association with the IP address indicated by the IP packet ( Step S18). When the gateway is not searched from the domain name routing table 16 (step S17; no domain name), the router 1 records the default gateway in the routing cache table 15 in association with the IP address indicated by the IP packet (step S19). ).

  The router 1 is searched from the routing cache table 15 when the gateway is searched from the routing cache table 15 (step S12; no IP address) or after the routing cache table 15 of steps S18 and S19 is updated. The IP packet is transferred to the gateway (step S20).

  According to the static domain name routing according to the present invention, after the terminal 4 inquires about the IP address corresponding to the domain name of the other party to be accessed, the IP packet indicating the destination can be appropriately routed by the IP address. . For example, the terminal 4 sends an inquiry packet indicating the domain name “aaa.co.jp” to the router 1 when attempting to access the computer indicated by the domain name “aaa.co.jp”. When the DNS cache table 16 associates the domain name “aaa.co.jp” with the IP address “200.200.200.1” as shown in FIG. A response packet indicating “200.200.200.1” is returned to the terminal 4. When the domain name routing table 17 associates the domain name “aaa.co.jp” with the gateway “100.100.100.1” as shown in FIG. As shown in the figure, the IP address “200.200.200.1” and the gateway “100.100.100.1” are recorded in the routing cache table 15 in association with each other. After updating the routing cache table 15 in this manner, the router 1 appropriately sends an IP packet indicating the destination with the IP address “200.200.200.1” to the gateway “100.100.100.1”. Can do.

  According to the static domain name routing according to the present invention, when the routing cache table 15 is lost and the domain name of the other party to which the terminal 4 tried to access is recorded in the domain name routing table 17, the router 1 The IP packet indicating the IP address of the other party can be appropriately routed. For example, when the terminal 4 tries to access the computer indicated by the domain name “aaa.co.jp” and the IP address “200.200.200.1”, the terminal 4 uses the IP address “200.200.200.1”. The indicated IP packet is sent to the router 1. When the routing cache table 15 has disappeared, the router 1 refers to the DNS cache table 16 or inquires the DNS server 5 to obtain the domain name “200.200.200.1” corresponding to the IP address “200.200.200.1”. “aaa.co.jp” is acquired. When the domain name routing table 17 associates the domain name “aaa.co.jp” with the gateway “100.100.100.1” as shown in FIG. .100.100.1 ". The router 1 further associates the IP address “200.200.200.1” indicated by the IP packet with the gateway “100.100.100.1” as shown in FIG. To record. After updating the routing cache table 15 in this manner, the router 1 appropriately sends an IP packet indicating the destination with the IP address “200.200.200.1” to the gateway “100.100.100.1”. Can do.

  According to the static domain name routing according to the present invention, when the routing cache table 15 and the DNS cache table 16 are lost, the domain name of the destination to which the terminal 4 tried to access is not recorded in the domain name routing table 17. Sometimes, the router 1 can appropriately route an IP packet indicating the IP address of the other party. For example, when the terminal 4 tries to access the computer indicated by the domain name “ddd.or.jp”, the terminal 4 sends an inquiry packet indicating the domain name “ddd.or.jp” to the router 1. The router 1 inquires of the DNS server 5 and acquires the IP address “200.200.200.5” corresponding to the domain name “ddd.or.jp”. As illustrated in FIG. 9, the router 1 records the domain name “ddd.or.jp” and the IP address “200.200.200.5” in association with each other in the DNS cache table 16. When the routing cache table 15 records the default gateway “100.100.100.2” as shown in FIG. 3, the router 1 executes the routing cache as shown in FIG. The IP address “200.200.200.5” is recorded in the table 15 in association with the default gateway “100.100.100.2”. After updating the routing cache table 15 in this manner, the router 1 appropriately sends an IP packet indicating the destination with the IP address “200.200.200.5” to the default gateway “100.100.100.2”. can do.

FIG. 1 is a block diagram showing an embodiment of the Internet. FIG. 2 is a block diagram showing an embodiment of a router according to the present invention. FIG. 3 is a diagram showing an embodiment of a routing cache table. FIG. 4 is a diagram showing an embodiment of the domain name routing table. FIG. 5 is a diagram showing an embodiment of the DNS cache table. FIG. 6 is a flowchart showing an embodiment of an operation for returning an IP address corresponding to a domain name in response to an inquiry. FIG. 7 is a flowchart showing an embodiment of an operation for routing an IP packet. FIG. 8 is a diagram showing a routing cache table that is updated when the terminal inquires about the IP address corresponding to the domain name of the partner to be accessed. FIG. 9 is a diagram showing a DNA cache table that is updated when the routing cache table and the DNS cache table are lost, and the domain name of the other party to which the terminal tried to access is not recorded in the domain name routing table. It is. FIG. 10 is a diagram showing a routing cache table updated when the routing cache table and the DNS cache table are lost, and the domain name of the partner to which the terminal tried to access is not recorded in the domain name routing table. It is.

Explanation of symbols

1: Router 2: Internet 3: Network 4: Terminal 5: DNS server 6-1 to 6-n: Gateway 11: Router body 12: Volatile memory 13: Non-volatile memory 14-1 to 14-n: Interface 15: Routing cache table 16: DNS cache table 17: Domain name routing table 20: Domain name collection unit 21: IP address search unit 22: Inquiry unit 23: IP address return unit 24: IP packet collection unit 25: Domain name search unit 26: Reverse inquiry unit 27: DNS table update unit 28: Gateway search unit 29: Routing table update unit 30: IP packet transfer unit 31: IP address 32: Gateway 41: Domain name 42: Gateway 51: Domain name 6 2: IP address

Claims (8)

A packet collector that collects data packets having a collection address from a terminal;
A packet transfer unit that refers to a routing table that associates a plurality of addresses with a plurality of gateways, and forwards the data packet to a corresponding gateway corresponding to the collection address among the plurality of gateways;
When the corresponding gateway is not searched from the routing table, a reverse lookup inquiry unit that collects an answer domain name corresponding to the collection address from a DNS server;
Referring to a domain name routing table that associates a plurality of domain names with a plurality of gateways, a gateway search unit that searches for an answer gateway corresponding to the answer domain name from among the plurality of gateways;
A router comprising: a routing table updating unit that records the collected address in association with the answer gateway in the routing table. In claim 1,
A DNS table update unit that records the collected address and the answer domain name in association with each other in a DNS table that associates a plurality of addresses with a plurality of domain names;
A domain name search unit for referring to the DNS table and searching a search domain name corresponding to the collection address from the plurality of domain names;
When the search domain name is searched from the DNS table, the gateway search unit refers to the domain name routing table to search a search gateway corresponding to the search domain name from the plurality of gateways,
The routing table updating unit records the collection address in the routing table in association with the search gateway. In claim 2,
A domain name collection unit for collecting a collection domain name from the terminal;
An inquiry unit that collects an answer address corresponding to the collection domain name from the DNS server;
An address reply unit for replying the answer address to the terminal;
The gateway search unit refers to the domain name routing table to search for a collection gateway corresponding to the collection domain name from the plurality of gateways,
The routing table updating unit records the answer address in the routing table in association with the collection gateway. In claim 3,
An address search unit that searches the DNS table for a search address corresponding to the collection domain name from the plurality of addresses;
The DNS table updating unit records the answer address and the collection domain name in association with each other in the DNS table when the search address is not searched from the DNS table,
The routing table updating unit records the search address in association with the collection gateway in the routing table when the search address is searched from the DNS table. Collecting a data packet having a collection address from a terminal;
Referring to a routing table associating a plurality of addresses with a plurality of gateways, transferring the data packet to a corresponding gateway corresponding to the collection address among the plurality of gateways;
Collecting an answer domain name corresponding to the collection address from a DNS server when the corresponding gateway is not retrieved from the routing table;
Searching for an answer gateway corresponding to the answer domain name from among the plurality of gateways with reference to a domain name routing table associating a plurality of domain names with a plurality of gateways;
A static domain name routing comprising: a routing step of recording the collected address in association with the answer gateway in the routing table. In claim 5,
Referring to a DNS table associating a plurality of addresses with a plurality of domain names and searching a search domain name corresponding to the collection address from the plurality of domain names;
When the search domain name is searched from the DNS table, referring to the domain name routing table, searching for a search gateway corresponding to the search domain name from among the plurality of gateways;
Recording the collected address in association with the search gateway in the routing table;
Static domain name routing further comprising the step of recording the collected address and the answer domain name in association with each other in the DNS table when the search domain name is not searched from the DNS table. In claim 6,
Collecting a collection domain name from the terminal;
Collecting an answer address corresponding to the collection domain name from the DNS server;
Returning the reply address to the terminal;
Searching the collection gateway corresponding to the collection domain name from the plurality of gateways with reference to the domain name routing table;
Static domain name routing further comprising the step of recording the answer address in association with the collection gateway in the routing table. In claim 7,
Searching the DNS table for a search address corresponding to the collection domain name from the plurality of addresses;
Recording the search address in association with the collection gateway in the routing table when the search address is searched from the DNS table;
Static domain name routing further comprising the step of associating the answer address with the collection domain name in the DNS table when the search address is not searched from the DNS table.

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