JP2000069072A - Device and method for determining transmission destination access server - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently use a line by searching an access server having the idle line before sending a packet when performing communication from a LAN terminal through an ISDN network. SOLUTION: This device is composed of a LAN terminal L and access servers 5 and 9 connected to a LAN, and in the case of performing the communication from the LAN terminal 1 through the ISDN network, the access servers 5 and 9 having the idle lines are searched. Concerning such a transmission destination access server determining device, the LAN terminal 1 is composed of a line connected access server table 32 for managing whether the line to send the packet is under connection or not, transmission destination access server retrieving means 33 for performing processing for sending the packet to the ISDN terminal and retrieving any access server having the idle line, packet output processing part 34 for performing the output processing of the packet, and connection/disconnection packet processing part 35 for receiving a connection packet, which is sent from the access server, reporting the connection of the line and a line disconnection notice packet reporting the connection of the line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access server determining apparatus including a LAN terminal connected to a LAN when searching for a free line when transmitting a packet, and an access server determining method in the apparatus. More particularly, the present invention relates to an access server determining apparatus and method for searching for an access server having a free line when a plurality of access servers exist.

[0002]

2. Description of the Related Art FIG. 26 is a diagram showing a conventional system configuration.

[0003] As shown in FIG.
31 and the access server 1
05, 109 and ISDN routers 113, 115, 11
7 and 119, and the LAN terminal 100
When transmitting a packet to the end of the DN network 112, the router refers to the routing table 131 in the LAN terminal 100 to determine to which of the access servers 105 and 109 the packet should be transmitted.

[0004] Another example of the conventional example is disclosed in Japanese Patent Application Laid-Open No. Hei 7-264211.
This means that a route information receiving unit that receives the route information transmitted on the local area network, a storage unit that stores the route information received by the route information receiving unit, and an unused address is extracted based on the contents of the storage unit. Extracting means, a confirming means for confirming the presence or absence of a host device having the address extracted by the extracting means, a setting means for setting the address of the own device based on the confirmation result of the confirming means, and a confirmation result of the confirming means. It comprises a holding means for holding and a means for extracting an unused address of the storage means, and automatically sets a network address in a short time without preparing an address server or the like for allocating a network address. is there. Specifically, upon receiving a RIP (Routing Information Protocol) response packet that is periodically transmitted from the host device, the contents of the RIP response packet are stored in a routing table, and the control unit transmits the information to a network that is not written in this routing table. An ARP (Address Resolution Protocol) request packet is transmitted to the address to determine the presence or absence of the host device.

[0005]

In the case shown in FIG. 26, when a packet is sent from the LAN terminal 100 to the destination of the ISDN network 112, the packet is sent to either of the access servers 105 and 109 with reference to only the routing table 131. Decided to send. However, since the routing table 131 does not manage whether or not the port connected to the ISDN is in use, if the access server to which the packet is transmitted has all the ports connected to the ISDN network 112 in use, the communication is performed. There was a problem that would be possible.

[0006] Further, in the device described in Japanese Patent Application Laid-Open No. 7-264211, an ARP request packet is transmitted only by referring to a routing table to determine the presence or absence of a host. Similarly, when there is a change in the contents of the routing table, there is a problem that the contents of the routing table must be rewritten and the presence or absence of the host must be searched again.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and when a LAN terminal performs communication via an ISDN network, a line terminal is transmitted before transmitting a packet. An object of the present invention is to efficiently use a line by searching for an available access server.

[0008]

In order to solve the above-mentioned problems, a destination access server determining apparatus according to the present invention comprises:
N. A destination access server determining apparatus, comprising: a LAN terminal connected to an N. and an access server, and searching for an access server having a vacant line when communicating from the LAN terminal via an ISDN network, LAN terminal
A line-connected access server table for managing whether a line to which a packet is to be transmitted is connected, and a destination access server for transmitting a packet to the ISDN network and searching for an access server having a vacant line. Search means, a packet output processing unit for performing a packet output process, and a connection / disconnection packet processing unit for receiving a connection packet for notifying connection of a line and a line disconnection notification packet for notifying disconnection of a line sent from the access server. When,
It is characterized by having.

Further, the access server has a line status confirmation packet response means for responding to the inquiry by the line status confirmation packet to the LAN terminal whether the line is free, and a counterpart management for managing the use status of the line to the destination address. It is characterized by having a table and a line connection / disconnection processing unit for notifying the LAN terminal of connection / disconnection of the line when the line is connected and disconnected.

The line-connected access server table of the LAN terminal includes a destination address portion in which a destination network address or host address is stored, and a line-connected network access server address portion in which a network address of the access server is stored. , And the contents of the access server address section during line connection are created by a packet output processing section and a connection / disconnection notification packet processing section.

The destination management table includes a destination address portion storing a destination network address or a host address, and an IS connected via an ISDN network.
An ISDN router name part for storing an ISDN router name for connecting a DN router, and a connection port part for storing a port name or a port number when a line is connected. The contents are created by a line connection / disconnection processing unit.

A first step of referring to the access server table during line connection to check whether there is an access server connected to the destination network. If there is no connected access server, a second step of making an inquiry to the access server by the destination access server searching means, and a line status confirmation packet response to the inquiry from the destination access server searching means A third step of responding by the means;
Receiving a response from the line status confirmation packet responding means in the step (4), the LAN terminal searches for an access server having a free line, and connecting / disconnecting the line when the line is connected / disconnected. A fifth step of notifying the connection / disconnection of the line from the processing unit to the LAN terminal and confirming the presence of the access server is included.

[0013] Further, the communication system includes an inter-network connecting device connected to a LAN and an access server. When communication is performed from a plurality of inter-network connecting devices via an ISDN network, an access server having a free line is searched for. The network connection device has a line connection access server table for managing whether a line is connected, a packet output to the ISDN network, and a vacant line. A destination access server search unit for searching for an access server, a packet output processing unit for outputting a packet to be sent to the ISDN network, a connection notification packet and a line for notifying the type of line sent from the access server Connection / disconnection packet processing unit for receiving a disconnection notification packet for notifying disconnection of It is characterized in.

Further, a first step of referring to the access server table during line connection and confirming whether there is an access server connected to the destination network, and If there is no connected access server, a second step of making an inquiry to the access server by the destination access server searching means, and a line status confirmation packet response to the inquiry from the destination access server searching means A third step of responding by the means;
Receiving a response from the line status confirmation packet responding means in the step (4), the inter-network connecting device searches for an access server having a free line, and when the line is connected and disconnected, A fifth step of notifying the connection / disconnection of the line from the connection / disconnection processing unit to the inter-network connecting device and confirming the existence of the access server is included.

By adopting the above configuration, according to the present invention, a LAN terminal and an inter-network connecting device are connected to an I / O terminal.
When transmitting a packet to an access server for communication via a public network such as an SDN, if there are a plurality of access servers, search for an access server having a free line and access the destination of the packet. It is possible to determine the server.

The access server responds to the inquiry from the LAN terminal or the inter-network connecting device by the line status confirmation packet responding means, thereby obtaining the LA.
The N terminal or the inter-network connecting device can search for an access server having a free line.

Further, the access server manages the use status of the line for the destination address by the destination management table, and when the line is connected and disconnected, the line connection / disconnection processing unit connects / disconnects the line to / from the LAN terminal. By notifying the disconnection, the LAN terminal or the inter-network connecting device can always manage whether there is an access server connected to the destination network.

[0018]

FIG. 1 is a block diagram showing a system configuration of a first embodiment of the present invention.

As shown in FIG. 1, this embodiment uses a LAN
(Local Area Network) LAN connected to 3
Terminal 1, two access servers, 5, 9 and LAN1
4, IS connected to 4, 16, 18, 20 respectively
And DN routers 13, 15, 17, and 19.

The LAN terminal 1 includes a routing table 31 storing path information, a line-connected access server table 32 for managing whether a line is connected,
A destination access server search unit 33 for outputting a packet to the ISDN network 12 and searching for an access server having an idle line; a packet output processing unit 34 for outputting a packet to be transmitted to the ISDN network 12;
The network connection device installed above (here, L
And a connection / disconnection notification packet processing unit 35 for transmitting a connection notification packet for notifying the AN terminal 1) that the line is connected and a disconnection notification packet for notifying that the line has been disconnected. .

The access servers 5 and 9 both include a line status confirmation packet responding unit 41 for confirming whether there is an access server already connected to the destination network from the destination access server searching unit 33, and a response to the destination address. A peer management table 42 for managing the use status of the line, and a LAN when the line is connected and disconnected;
A line connection / disconnection processing unit 43 for notifying the terminal 1 of connection / disconnection of the line.

In FIG. 1, a LAN terminal 1 and access servers 5 and 9 are connected to ports 2, 4 and 8, respectively. The access server 5 is connected to the ISDN through ports 6 and 7 and the access server 9 is connected to port 1
0, 11 connected to the ISDN 12
Routers 13, 15, 17, and 19 are also connected to ISDN network 12. The ISDN router 13 is connected to the LAN 14
The ISDN router 15 is connected to the LAN 16, the ISDN router 17 is connected to the LAN 18, and the ISDN router 19 is connected to the LAN 2.
0.

The ISDN routers 13, 15, 17,
Reference numeral 19 denotes an apparatus for selecting a route in the third network layer of the OSI (Open Standard Interconnection) reference model and performing interconnection.

Packet output processing unit 34 of LAN terminal 1
Performs a packet output process in cooperation with the routing table 31, the line-connected access server table 32, and the destination access server search means 33. The destination access server searching means 33 searches for an access server having a free line. When the line is connected / disconnected, the line connection / disconnection processing unit 43 of each of the access servers 5 and 9 updates the destination management table 42 and notifies a connection / disconnection notification packet to a terminal on the LAN 3 or an inter-network connection device. Is sent. The line connection / disconnection processing unit 43
Notification of connection to a LAN terminal when a call is made from the SDN routers 13, 15, 17, and 19, and other LAN terminals and networks when the LAN terminal 1 makes a call via the access servers 5 and 9 by a trigger A notification of connection to the interconnection device and a notification of disconnection of the line to the LAN terminal 1 are provided. Also,
The connection / disconnection notification packet processing unit 35 receives the connection / disconnection notification packet sent from the access servers 5 and 9, and thereby receives the line-connected access server table 32.
Update.

FIG. 2A shows the LA used in this embodiment.
2 (b) shows the routing table 31, FIG. 2 (c) shows the access server table 32 during line connection, and FIG. 2 (d) shows the storage location of each table in the N terminal 1 and the access servers 5 and 9. FIG. 4 is a diagram showing a configuration of a destination management table 42. As shown in FIG. 2A, the routing table 31 and the access server table 3 during line connection
2 is stored in the LAN terminal 1 and the destination management table 42 is stored in the access servers 5 and 9.

In FIG. 2B, a routing table 31 includes a destination address section 31a in which a destination network address or an IP address is stored, and an adjacent network device to which a packet is to be transmitted (here, access servers 5, 9). ) Comprises a Next Hop address section 31b in which the network address is stored, and an output port section 31c in which the port name or port number of the LAN terminal 1 to which the packet is transmitted is stored. The destination address section 31a, the next hop address section 31b, and the output port section 31c correspond to each other, and store contents indicating which port a packet should be sent to which device. The contents of each part of the routing table 31 are dynamically or statically created by the routing table creating unit 34.

In FIG. 2C, the access server table 32 during line connection has a destination address section 32a in which a destination network address or host address is stored.
And a line-connected access server address section 32b in which the network address of the access server is stored. Similarly to the routing table 31, the destination address section 32a and the line-connected access server address section 32b correspond to each other.
The contents indicating whether there is an access server connected to the line is stored in the access server address section 32b during the line connection, and the contents of the destination address section 32a are the destination address 31a of the routing table 31 and the Next address.
The contents of the hop address 31b are reflected, and the contents of the access server address section 32b during line connection are the packet output processing section 34 and the line connection / disconnection notification packet processing section 35.
Created by

In FIG. 2D, the destination management table 42 includes a destination address section 42a in which a destination network address or host address is stored, and an ISDN 1
ISDN router name part 4 for storing an ISDN router name for identifying an ISDN router connected via 2
2b and a connection port section 42c in which port names or port numbers of the connected access servers 5 and 9 are stored.
And Note that the ISDN router name 42b may store a telephone number instead of the ISDN router name. The destination management table 42 is also a routing table 31 and an access server table 32 during line connection.
Similarly to the above, the destination address part 42a, the ISDN router name part 42b, and the connection port part 42c correspond to each other, and indicate that the destination address is ahead of which ISDN router and to which port it is connected. Is stored. The destination address section 42a and the ISDN router name section 42b are created statically by the destination management table creation section 44, and the contents of the connection port section 42c are created by the line connection / disconnection processing section 43.

Further, the destination address 3 in the line-connected access server table 32 stored in the LAN terminal 1
The registered content of 2d and the registered content of the destination address 42a of the destination management table 42 stored in the access servers 5 and 9 must match, that is, be the same.

FIG. 3 is a diagram showing portions indicated by addresses and ports of each table used in this embodiment. As shown in the figure, the destination address part 31a of the routing table 31 stores a host or network address of a destination to which a packet is transmitted via the ISDN network 12, and a Next Hop address 32a is an access server which transmits the packet. And the output port section 31c indicates the output port of the LAN terminal 1 to which the packet is transmitted.

The destination address 32a of the line-connected access server table 32 stores the host address or network address of the same destination as the destination address part 31a of the routing table 31, and the line-connected access server address part 32b stores the destination address part. The address of the access server 5, 9 corresponding to 32a is stored.

A destination host or network address to which the same packet as the routing table 31 and the line-connected access server table 32 is transmitted is also stored in the destination address section 42a of the destination management table 42.
The ISDN router name 42b indicates the name of the ISDN router that reaches the target host or network, and the connection port 42c indicates the ports 13, 15, 17, and 19 of the ISDN router that reaches the target host or network.

FIG. 4 is a diagram showing the correspondence between address pointers in each table. As shown in FIG. 4, the destination address part 31a of the routing table 31 corresponds to the destination address part 32a of the line connection access table 32 and the destination address part 42a of the destination management table 42, and has the same host or network address. Pointing to. Further, Next in the routing table 31
The hop address part 31b and the line-connected access server address part 3 of the line-connected access server table 32
2b is corresponding and points to the address of the same access server 5, 9.

As described with reference to FIG. 2, each table is composed of the routing table creation unit 36 and the destination management table 44.
Created by However, the contents of each table are updated or deleted as follows depending on whether the line is free or connected / disconnected.

FIG. 5A shows the processing of the routing table 31 when the line is free, and FIG. 5B shows the processing of the routing table 31 and the access server table 32 when the line is not used. , FIG.
FIG. 6C shows processing of the routing table 31 at the time of line connection and the access server table 32 during line connection.
Is the access server table 3 during line connection when the line is disconnected
FIG. 9 is a diagram showing a process 2;

First, when the line shown in FIG. 5A is free, the destination address (1
NextHop addresses (3.0.0.4) and (3.0.0.8) corresponding to (4.0.0.0/8) are set as the NextHop addresses of the access server.

Next, when the line shown in FIG. 5B is not vacant, the destination address (14.0.0.0/8) of the packet extracted from the received packet, that is, the destination address of the routing table 31 is used. (14.0.0.0/
8), the NextHop address (3.0.0.
8) is registered in the line connection access server address 32b of the line connection access server table 3.

In the case of the line connection shown in FIG. 5C, the line connection access server address 32b of the line connection access server table 32 is stored in the next hop address (3.0.0.0/8) of the routing table 31.
To update.

When the line is disconnected as shown in FIG. 6, the access server address (3.0.0.8) during the line connection is deleted from the access server table 32 during the line connection.

FIG. 7 shows a connection / connection sent from the line connection / disconnection processing unit 43 of the access servers 5 and 9 to the network.
It is a figure showing the frame composition of a disconnection notice packet. As shown in the figure, the connection / disconnection notification packet is a 6-byte MAC (M
edia Access Control)
0, 4 byte IP (Internet Protocol) header 51,
4-byte destination address 52, 1-byte event part 5
3 The frame length is 15 bytes in total, the destination address section 52 stores the network address or host address of the destination, and the event section 52 stores either “connection (00000000)” or “disconnection (00000001)”. When the “connection” is stored, it indicates that the line corresponding to the destination address stored in the destination address 52 is connected, and when the “disconnection” is stored, the line is connected to the destination address 52. Indicates that the line for the stored destination address has been disconnected.

FIG. 8 is a diagram showing a description order of the first embodiment of the present invention. Here, the figure numbers shown on the right side of the figure are the figure numbers of the flowchart in which the explanation of the operation is described.

FIG. 9 is a diagram showing a general flow of the operation of this embodiment.

As shown in FIG. 9, the LAN terminal 1, which is executed in the following order, refers to the line-connected access server table 32 when transmitting a packet to the destination of a public network such as ISDN. It is checked whether there is an access server connected to the network (), and if there is no access server connected, an inquiry is made to the access servers 5 and 9 by the destination access server search means 33 ( ). In response to the inquiry from the transmission destination access server search means 33, the line status confirmation packet response means 41 of the access servers 5 and 9 returns a response, whereby the LAN terminal 1 knows the access server having a free line. Can be.

The access servers 5 and 9 manage the status of use of the line to the destination address to which the packet is transmitted by the destination management table 42. When the line is connected / disconnected, the line connection / disconnection processing unit By transmitting a line connection / disconnection packet from the terminal 43 to the LAN terminal 1 (), the LAN terminal 1 can always check whether there is an access server connected to the destination network.

FIG. 8 is a diagram showing the order of explanation of the operation of this embodiment. Here, the figure numbers shown on the right side of the figure are the figure numbers of the flowchart in which the explanation of the operation is described.

FIG. 10A shows FIGS. 11 and 1 to be described later.
FIG. 2 is a diagram showing a hierarchy of operations in the flowchart of FIG. A detailed description of the step S1 of the operation 60 of the packet processing unit is the operation 61 of the transmission destination access server search means thereunder. Also, the line status confirmation packet responding unit 62 has been described in detail in S2 of the operation of the destination access server searching unit.

FIG. 10 (b) is a view corresponding to FIGS.
FIG. 6 is a diagram showing an execution order of the flowchart in FIG. FIG.
As shown in FIG. 11B, FIGS. 11, 12 and 14 are executed in the order shown in FIG. 11, which is similar to a subroutine or function of a procedural language.

Next, the operation of the present embodiment will be described in detail in the order shown in FIG. 8 with reference to FIGS. 1, 11 to 16.

(1) Operation of Packet Output Processing Unit FIG. 11 is a flowchart showing an operation when the packet output processing unit 34 of the LAN terminal 1 transmits a packet. Here, in FIG. 3, the LAN terminal 1
The host 21 connected to the LAN 14 via the DN router 13 (network address: 14.0.0.0/
The operation when transmitting a packet to 8) will be described. Here, 8 of (14.0.0.0/8) indicates that the first eight bits of the network address are the network address part.

Referring to FIG. 11, first, the destination address (14.0.0.0/8) of the packet is extracted (step S100). Next, the extracted destination address (1
4.0.0.0/8) is registered in the destination address part 31a of the routing table 31 in FIG. 2B (step S101). If registered, the destination address extracted from the packet (14.
0.00.0 / 8) for all Next Hop
The addresses (3.0.0.4) and (3.0.0.8) are extracted (step S102). If the destination address is not registered here, the packet is discarded, and the process ends (step S103).

Note that the Next Hop address (3.
0.0.4) is the IP address of port 4 of access server 5 (3.0.0.8) is the port 8 of access server 9
IP address. Next, the destination address (14.0.0.0/
8) is registered as the destination address 32a of the access server table 32 during line connection in FIG. 2B (step S104). If registered, the destination address (14.0.1) extracted in step S100 is stored in the line-connected access server table 32 of FIG.
It is checked whether the line-connected access server address 32b corresponding to (0.0 / 8) is registered (step S1).
06). If it is not registered here, the Ne extracted in step S102 as in the normal routing
The packet is transmitted to any one of the xt Hop addresses, and the process ends (step S105). Step S1
If it is determined in step 06 that the access server address 32b during line connection is not registered, the transmission destination access server search means 33 searches for an access server having a free line (step S108). If registered, the packet is transmitted to the registered access server, and the process ends (step S107).

The operation of the packet output processing section 34 of the LAN terminal 1 in FIG. 11 has been described so far. Next, the operation of the destination access server search means in step S108 in FIG. 11 will be described.

(2) Operation of destination access server searching means FIG. 12 is a flowchart showing the operation of the destination access server searching means 33 of the LAN terminal 1.

Referring to FIG. 12, first, a counter n for counting the number of Next Hop addresses 31a in the routing table 31 is set to 1 (step S2).
00). Next, n = 2nd Next Hop address (3.0.0.4) is extracted (step S201).
Then, the Nex extracted in step S101 of FIG.
A line status confirmation packet is sent to the t-hop address (3.0.0.4) (step S202), and it is confirmed whether or not there is a free line in the access server 5 (step S203).

FIG. 13 is a flowchart showing the operation of another embodiment of the destination access server search means 33.

Referring to FIG. 13, first, a line status confirmation packet is broadcasted to LAN 3 to which access servers 5 and 9 are connected (step S).
300). It is confirmed whether or not at least one response indicating “there is an available line” is received in the response result by the line status confirmation packet responding unit 41 of the access servers 5 and 9 (step S30).
1). If there is a response of "there is a free line" (step S301), the IP address of the access server which first returned the response of "there is a free line" is set as the packet transmission address (step S302), and "there is a free line". Is not received, the response result is set to "no available line (no output destination)" (step S305).

With the configuration shown in FIG. 13, the LAN terminal 1 does not need to send the line status confirmation packet to the access servers 5 and 9 many times.

The explanation of the destination access server searching means 33 of the LAN terminal 1 in FIG. 12 is now complete. Next, the line status confirmation packet transmitted from the destination access server searching means 33 in step S203 in FIG. Will be described when the line status confirmation packet responding means 41 of the access servers 5 and 9 receives this.

(3) Operation of Line Status Confirmation Packet Response Unit FIG. 14 is a flowchart showing the operation of the line status confirmation packet response unit 41 of each of the access servers 5 and 9.

Referring to FIG. 14, first, when the line connection status confirmation packet response means 41 receives a line status confirmation packet from the LAN terminal 1 (step S400), the IS
It is checked whether there is an unused (disconnected) port among the ports connected to the DN network 12 (step S4).
01). If there is an unused port, the LAN terminal 1 is replied to "there is a free line" (step S402), and if there is no unused port, the reply is "there is no free line" (step S403).

Here, returning to step S203 of FIG. 12, it is confirmed whether or not the response result from the line status confirmation packet responding means 41 of the access server 5 is "there is an available line" (step S203). If the response result in step S203 is “there is an available line”, the result of the destination access server searching means 33 is used as the packet transmission address using the Next Hop address extracted in step S201 (step S206). If step S20
If the response result of No. 3 is “no free line”, it is checked whether the Next Hop address extracted in step S201 is the last address of the extracted Next Hop address (step S204), and if it is the last address, it is transmitted. The result of the destination access server search means 33 is set to "no free line" (step S207). If it is not the last address, the value of the counter n is incremented by 1 and the process returns to step S201 (step S205).

Here, in this embodiment, for example, there is no unused line in the access server 5 and the access server 9
Suppose there is an unused line. In that case, Next
If the counter of the Hop address is n = 1, the response result in step S203 is "no free line", and since (3.0.0.4) is not the last address in step S204, the counter n is set to 1 Is incremented to 2 and n = n in the extracted Next Hop address.
The second registered next hop address (3.0.0.8) is extracted. Then, a line status confirmation packet is sent to the extracted Next Hop address (3.0.0.8), and it is confirmed whether or not the access server 9 has a free line. Since the response result is “there is a vacant line”, the Next in which the response result is extracted
Hop address (3.0.0.8).

Here, returning to step 108 in FIG.
Check if the response result is "No output destination" (Step 1
08) If there is a free line in step S108,
The line-accessed access server table 32 is used as the line-connected access server corresponding to the destination address from which the result searched by the transmission destination access server searching means 33 is extracted.
Is registered in the access server address section 32b during line connection (step S110). Then, the packet is transmitted to the extracted N-th Next Hop address (step S111). If there is no free line in step S108, the packet is discarded and the process is terminated (step S1).
09). However, in the present embodiment, the response result in step S108 is not “no free line”, but the response result in step S108 in the line-connected access server table 32 in FIG.
Next Hop address extracted in step 102 (3.
0.0.8) to the destination address (14.0.0.0/8)
Is registered as an access server address during line connection for. Then, the Next Hop address (3.0.
0.8).

(4) Operation at Line Connection of ISDN Network FIG. 15 shows the operation of the line connection / disconnection processing unit 43 of the access servers 5 and 9 when the lines of the ISDN network 12 of the access servers 5 and 9 are connected. Operation (Steps S400 to S40)
3) is a flowchart showing the operation (steps S404 to S408) of the connection / disconnection notification packet processing unit 35 of the LAN terminal 1;

Here, as an example, the operation in the case of connecting via the port 10 of the access server 9 and the ISDN router 13 will be described.

Referring to FIG. 15, when a line is connected by the access server 9 (step S400), the access server 9 performs CHA of PPP (Point to Point Protocol).
P (Challenge handshake Authentication Protocol)
ISDN router name (ISDN router 13) using PAP (Password Authentication Protocol) or the like
Is confirmed (step S401). Next, in the access server 9, the ISDN router name (ISDN) confirmed in step S401 in the destination management table of FIG.
The destination address (14.0.0.
0/8) is extracted (step S402). Then I
Register the port number (port 10) corresponding to the SDN router name (ISDN router 13) (step S40)
3). Next, the access server 9 extracts the destination address (14.0.
0.0 / 8) (in the event section of FIG. 7, the event section is “connection (00000000)”) by broadcast (step S404). Then, upon receiving the connection notification packet (step S405), the LAN terminal 1 extracts the IP address (3.0.0.8) of the access server 9 that transmitted the connection notification packet (step S406).
At the same time, the LAN terminal 1 extracts the destination address (14.0.0.0/8) included in the connection notification packet (step S407). Then, the LAN terminal 1 checks in step S4 in the access server table 32 during line connection.
The access server address during line connection corresponding to the destination address extracted in step 07 is updated to the IP address of the access server extracted in step S403 (step S4).
08).

Note that PAP is a protocol for confirming a partner by a user ID and a password after a PPP link is established. The transmission of the ID and the password is repeated until the authenticator confirms this or the line is disconnected.
However, there is a security problem with this, and a stronger authentication method has been proposed. That is CHAP.

CHAP is a stronger authentication protocol which solves the security problem of PAP. After establishing a PPP link, the authenticator firstly establishes a kind of encryption key, challe.
Send an nge message. In response, the user replies with a value obtained by a cryptographic calculation method such as a hash. The authenticator compares this value with the value calculated by the user, and if they match, permits the connection, and if they do not match, disconnects the line. Thus, in CHAP, the number of repetitions and the time limit,
The variable allenge number reduces the risk of hacks due to repetition.

(5) Operation at the time of disconnection of the line of the ISDN network FIG.
Operation of Line Connection / Disconnection Processing Unit 43 of Access Servers 5 and 9 when Line 2 is Disconnected (Steps S500 to S500)
S503) and operation of the connection / disconnection notification packet processing unit 35 of the LAN terminal 1 (steps S504 to S506).
It is a flowchart which shows.

Here, as an example, an operation when the line connected to the ISDN router 19 via the port 11 of the access server 9 is disconnected will be described.

Referring to FIG. 16, when the line is disconnected by the access server 9 (step S500), the access server 9 sets the port number disconnected in step S500 in the destination management table 42 of FIG. The corresponding destination address (16.0.0.0/8) is extracted (step S501). Next, the access server 9 deletes the disconnected port number from the connection port 42c of the destination management table 42 (step S502). In the access server 9, the disconnection notification packet relating to the destination address (16.0.0.0/8) extracted in step S501 for the LAN 3 (the event section in FIG.
1))) by broadcast (step S50)
3). When receiving the disconnection notification packet (step S504), the LAN terminal 1 extracts the destination address (16.0.0.0/8) included in the disconnection notification packet (step S505). Next, the LAN terminal 1 checks the destination address (16.0.0.
The access server address (3.0.0.8) during line connection corresponding to (0/8) is deleted (step 506).

In this embodiment, one LAN terminal 1, two access servers 5, 9 and four ISDN routers 1
Although the configuration including 3, 16, 18, and 20 has been described, the present embodiment is not limited to these configurations, and a plurality of LAs may be used.
N terminals and an access server may be used. Multiple L
When the AN terminal and the access server are used, the probability of existence of a free line having a free line increases, and accordingly, the probability of successful search for a free line also increases.

As described above, in this embodiment, the LAN
When the terminal 1 sends a packet to the access servers 5 and 9 to perform communication via a public line such as ISDN, if there are a plurality of access servers, an access server having a free line is searched for. By doing so, it becomes possible to determine the destination access server of the packet.

Also, if the network connection device is an ISDN
When sending a packet to an access server to communicate via a public line such as a public network, if there are multiple access servers, the access destination that has a free line is searched for The server can be determined.

In this embodiment, a case has been described in which a packet is transmitted using the IP address of the third layer of the OSI reference model, but the same applies to the case of using the address of the fifth layer of the network layer. This embodiment can be implemented in the following manner.

FIG. 17 is a block diagram showing a system configuration according to the second embodiment of the present invention.

This embodiment is an example in which an inter-network connecting device 1 ′ such as a router is used instead of the LAN terminal 1.

As shown in FIG. 17, this embodiment uses a LAN
3, two access servers, 5, 9 and LANs 14, 16, 18,
20, four ISDN routers 13, each connected to
15, 17, and 19.

The inter-network connecting apparatus 1 ′ includes a routing table 31 ′ in which path information is stored, a line-connected access server table 32 ′ for managing whether or not a line is connected, and a packet connection to the ISDN 12. Destination access server searching means 33 'for searching for an access server having an output line and a free line;
And a packet output processing unit 34 'for outputting packets to be transmitted to the LAN 2 and an inter-network connecting device (here, the inter-network connecting device 1') installed on the LAN 3 that the line is connected. Connection / disconnection notification packet processing unit 35 'for transmitting a connection notification packet to be transmitted and a disconnection notification packet for notifying that the line has been disconnected.
And

The access servers 5 and 9 both include a line status confirmation packet response unit 41 for checking whether there is an access server already connected to the destination network from the destination access server search unit 33 ', and a destination address. And a line connection / disconnection processing unit 43 for notifying the inter-network connecting device 1 'of connection / disconnection of the line when the line is connected / disconnected. Have.

In FIG. 17, the inter-network connecting device 1 ′ and the access servers 5 and 9 are respectively connected to ports 2 and
4, 8 are connected. The access server 5 is connected to ports 6 and 7, and the access server 9 is connected to ports 10 and 7.
The connection 11 is connected to the ISDN network 12, and the ISDN routers 13, 15, 17 and 19 are also connected to the ISDN network 12. The ISDN router 13 connects the LAN 14 to the
The SDN router 15 is connected to the LAN 16 by the ISDN router 17.
Is connected to the LAN 18, and the ISDN router 19 is connected to the LAN 20.

The ISDN routers 13, 15, 17,
Reference numeral 19 denotes a device for selecting a route in the third network layer of the OSI reference model and performing interconnection.

The packet output processing unit 34 'of the inter-network connecting apparatus 1' performs a packet output process in cooperation with the routing table 31 ', the line-connected access server table 32', and the destination access server search means 33 '. . Also, the destination access server search means 33 '
Searches for an access server having a free line. When the line is connected / disconnected, the line connection / disconnection processing unit 43 of each of the access servers 5 and 9 updates the destination management table 42 and notifies a connection / disconnection notification packet to a terminal on the LAN 3 or an inter-network connection device. Is sent. The line connection / disconnection processing unit 43 is provided for the ISDN routers 13, 15, 1
Notification of connection to the LAN terminal when a call is made from the connection 7 or 19, and connection to another connection between the networks when the network connection device 1 'makes a call via the access servers 5 and 9 by a trigger. And a disconnection notification of the line to the inter-network connecting apparatus 1 '. The connection / disconnection notification packet processing unit 35 'receives the connection / disconnection notification packet sent from the access servers 5 and 9, and updates the access server table 32' during line connection.

FIG. 18 is a diagram showing a description order of the second embodiment of the present invention. Here, the figure numbers shown on the right side of the figure are the figure numbers of the flowchart in which the explanation of the operation is described.

FIG. 19 is a diagram showing a general flow of the operation of this embodiment.

As shown in FIG. 19, the inter-network connecting apparatus 1 'executed in the following order refers to the line-connected access server table 32 when transmitting a packet to the destination of a public network such as ISDN. To determine whether there is an access server connected to the destination network (). If there is no access server connected to the destination network, the destination access server search means 33 ′ checks the access servers 5 and 9. Make an inquiry (). In response to the inquiry from the transmission destination access server search means 33 ', the line status confirmation packet response means 41 of the access servers 5 and 9 returns a response, whereby the inter-network connecting device 1' Know the server.

The access servers 5 and 9 manage the status of use of the line to the destination address to which the packet is transmitted by the destination management table 42. When the line is connected / disconnected, the line connection / disconnection processing unit By transmitting a line connection / disconnection packet from the network connection device 43 to the network connection device 1 ′ (), the network connection device 1 ′ can always check whether there is an access server connected to the destination network.

Next, the operation of the present embodiment will be described in detail in the order shown in FIG. 18 with reference to FIGS. 17, 20 to 25.

(1) Operation of Packet Output Processing Unit FIG. 20 is a flowchart showing the operation when the packet output processing unit 34 'of the network connection device 1' transmits a packet. Here, in FIG. 3, the inter-network connecting device 1 ′ is connected to the L through the ISDN router 13.
The operation when transmitting a packet to the host 21 (network address: 14.0.0.0/8) connected to the AN 14 will be described. Here, (14.
8 of (0.00.0 / 8) indicates that the first eight bits of the network address are the network address part.

Referring to FIG. 20, first, the destination address (14.0.0.0/8) of the packet is extracted (step S700). Next, the extracted destination address (1
4.0.0.0/8) is registered in the destination address section 31a 'of the routing table 31' in FIG. 2B (step S701). If registered, the destination address (1
4.0.0.0/8) for all Next H
op address (3.0.0.4), (3.0.0.8)
Is extracted (step S702). If the destination address has not been registered, the packet is discarded and the process ends (step S703).

Note that the Next Hop address (3.
0.0.4) is the IP address of port 4 of access server 5 (3.0.0.8) is the port 8 of access server 9
IP address. Next, the destination address (14.0.0.0/
8) is registered as the destination address 32a 'of the line-connected access server table 32' of FIG. 2B (step S704). If registered, access server table 3 during line connection in FIG.
2 ′, the destination address (1) extracted in step S700.
It is checked whether the access server address 32b 'during line connection corresponding to (4.0.0.0/8) is registered (step S706). If not registered here, the packet is sent to any of the Next Hop addresses extracted in step S702 as in normal routing, and the process ends (step S705). If it is determined in step S706 that the access server address during line connection 32b 'is not registered, the destination access server searching means 33' searches for an access server having a free line (step S708). If registered, the packet is transmitted to the registered access server, and the process ends (step S707).

The operation of the packet output processing unit 34 'of the inter-network connecting apparatus 1' of FIG. 20 has been described so far. Next, the operation of the destination access server searching means in step S708 of FIG. 20 will be described.

(2) Operation of destination access server searching means FIG. 21 is a flowchart showing the operation of the destination access server searching means 33 'of the network connection apparatus 1'.

Referring to FIG. 21, first, a counter n for counting the number of Next Hop addresses 31a 'in the routing table 31' is set to 1 (step S800). Next, the n = 2nd Next Hop address (3.0.0.4) is extracted (step S80).
1). Then, a line status confirmation packet is transmitted to the Next Hop address (3.0.0.4) extracted in step S701 of FIG. 20 (step S802),
It is checked whether there is a free line in the access server 5 (step S803).

FIG. 22 is a flowchart showing the operation of another embodiment of the transmission destination access server search means 33 '.

Referring to FIG. 22, first, a line status confirmation packet is broadcast to LAN 3 to which access servers 5 and 9 are connected (step S).
900). It is checked whether at least one response indicating “there is an available line” is received in the response result by the line status confirmation packet responding means 41 of the access servers 5 and 9 (step S90).
1). If there is a response of “there is a vacant line” (step S901), the IP address of the access server that first returned the response of the “available line” is set as the packet transmission address (step S902), and “there is a vacant line exists”. If there is no response of "", the response result is set to "no available line (no output destination)" (step S905).

With the configuration shown in FIG. 22, the inter-network connecting device 1 ′ does not need to send the line status confirmation packet to the access servers 5 and 9 many times.

The description of the destination access server searching means 33 'of the inter-network connecting apparatus 1' in FIG. 21 is now complete, and then the destination access server searching means 33 'in step S803 of FIG. The operation when the line status confirmation packet response unit 41 of the access servers 5 and 9 receives the line status confirmation packet will be described.

(3) Operation of Line Status Confirmation Packet Response Unit FIG. 23 is a flowchart showing the operation of the line status confirmation packet response unit 41 of each of the access servers 5 and 9.

Referring to FIG. 23, first, when the line connection status confirmation packet responding unit 41 receives a line status confirmation packet from the inter-network connecting device 1 ′ (step S 1000), the line connection status It is checked whether there is an unused (disconnected) port (step S1001). If there is an unused port, it responds to the inter-network connecting device 1 'with "available line" (step S1002), and if there is no unused port, it responds with "no available line" (step S1003).

Here, returning to step S803 of FIG. 21, it is checked whether or not the response result from the line status confirmation packet responding means 41 of the access server 5 is “there is an available line” (step S803). If the response result in step S803 is “there is a vacant line”, the result of the destination access server searching means 33 ′ is used as the packet transmission address using the Next Hop address extracted in step S801 (step S806). If step S8
If the response result of No. 03 is “no free line”, it is checked whether the Next Hop address extracted in step S801 is the last address of the extracted Next Hop address (step S804). The result of the access server search means 33 'is set to "no free line" (step S807). If it is not the last address, the value of the counter n is incremented by 1 and the process returns to step S801 (step S805).

Here, in this embodiment, for example, there is no unused line in the access server 5 and the access server 9
Suppose there is an unused line. In that case, Next
When the counter of the Hop address is n = 1, the response result in step S803 is “no free line”, and in step S804, (3.0.0.4) is not the last address. Is incremented to 2 and n = n in the extracted Next Hop address.
The second registered next hop address (3.0.0.8) is extracted. Then, a line status confirmation packet is sent to the extracted Next Hop address (3.0.0.8), and it is confirmed whether or not the access server 9 has a free line. Since the response result is “there is a vacant line”, the Next in which the response result is extracted
Hop address (3.0.0.8).

Now, returning to step 708 in FIG.
Check if the response result is "No output destination" (Step 7
08), if there is a free line in step S708,
A line-connected access server table 3 as a line-connected access server corresponding to the extracted destination address obtained by the search result by the transmission destination access server searching means 33 '
It is registered in the access server address section 32b 'during line connection of 2' (step S710). Then, the extracted N
The packet is transmitted to the next Next Hop address (step S711). If there is no free line in step S708, the packet is discarded, and the process ends (step S709). However, in the present embodiment, step S70
The response result of No. 8 is not "No free line", but FIG.
Of the next hop address (3.0.0.8) extracted in step S702 in the line connection access server table 32 'of the destination address (14.0.0.0).
/ 8) is registered as an access server address during line connection. Then, the Next Hop address (3.
0.0.8).

(4) Operation at Line Connection of ISDN Network FIG. 24 shows the operation of the line connection / disconnection processing unit 43 of the access servers 5 and 9 when the lines of the ISDN network 12 of the access servers 5 and 9 are connected. Operation (Steps S1100 to S1)
103), and the operation of the connection / disconnection notification packet processing unit 35 'of the network connection device 1 (step S110).
4 to S1108).

Here, as an example, the operation in the case where the connection is made via the port 10 of the access server 9 and the ISDN router 13 will be described.

Referring to FIG. 24, when the line is connected by the access server 9 (step S1100), the access server 9 confirms the name of the ISDN router (ISDN router 13) of the other party by using CHAP or PAP of PPP (step S1100). Step S1101). Next, at the access server 9,
Step S1 in the destination management table of FIG.
101, the destination address (14.0.0.0/) corresponding to the ISDN router name (ISDN router 13).
8) is extracted (step S1102). Then, IS
The port number (port 10) corresponding to the DN router name (ISDN router 13) is registered (step S110).
3). Next, in the access server 9, the destination address (14.0.
(0.0 / 8) is broadcast (step S1104). Then, upon receiving the connection notification packet (step S1105), the inter-network connecting device 1 ′ extracts the IP address (3.0.0.8) of the access server 9 that transmitted the connection notification packet (step S1106), and extracts the IP address (step S1106). The connection device 1 ′ transmits the destination address (1
4.0.0.0/8) (step S110).
7). Then, the inter-network connection device 1 'updates the line-connected access server address corresponding to the destination address extracted in step S1107 to the IP address of the access server extracted in step S1103 in the line-connected access server table 32'. (Step S1108).

Note that PAP is a protocol for confirming a partner with a user ID and a password after a PPP link is established. Transmission of an ID and a password is repeated until an authenticator confirms this or the line is disconnected.
However, there is a security problem with this, and a stronger authentication method has been proposed. That is CHAP.

CHAP is a stronger authentication protocol that solves the security problem of PAP. After a PPP link is established, an authenticator firstly requires a kind of encryption key, challe.
Send an nge message. In response, the user replies with a value obtained by a cryptographic calculation method such as a hash. The authenticator compares this value with the value calculated by the user, and if they match, permits the connection, and if they do not match, disconnects the line. Thus, in CHAP, the number of repetitions and the time limit,
The variable allenge number reduces the risk of hacks due to repetition.

(5) Operation when ISDN Network Line is Disconnected FIG.
Operation of the line connection / disconnection processing unit 43 of the access servers 5 and 9 when the line 2 is disconnected (step S1200)
To S1203) and the operation (steps S1204 to S1206) of the connection / disconnection notification packet processing unit 35 ′ of the network connection device 1 ′.

Here, as an example, the operation when the line connected to the ISDN router 19 via the port 11 of the access server 9 is disconnected will be described.

Referring to FIG. 25, when the line is disconnected by the access server 9 (step S1200), the access server 9 sets the port number disconnected in step S1200 in the destination management table 42 of FIG. The corresponding destination address (16.0.0.0/8) is extracted (step S1201). Next, at the access server 9,
The disconnected port number is deleted from the connection port 42c of the destination management table 42 (step S1202). Step S120 is performed on the LAN 3 by the access server 9.
Destination address extracted in 1 (16.0.0.0/8)
Disconnection notification packet (the event section in FIG.
(00000001) ”) by broadcast (step S1203). Then, the network connection device 1 '
Receives the disconnection notification packet (step S50).
4), the destination address (1
6.0.0.0/8) (step S120).
5). Next, the network connection apparatus 1 'checks the destination address (16.0.0.
0/8) is deleted (step 1206).

In this embodiment, one inter-network connecting device 1 ', two access servers 5, 9 and four I
Although the configuration including the SDN routers 13, 16, 18, and 20 has been described, the present embodiment is not limited to these configurations, and a plurality of network connection devices and access servers may be used. When a plurality of network connecting devices and an access server are used, the existence probability of a free line having a free line increases, and accordingly, the probability of successful search for a free line also increases.

As described above, in the present embodiment, when the inter-network connecting apparatus 1 'sends a packet to the access servers 5 and 9 for communication via a public line such as ISDN, the access server 1' When there are a plurality of access servers, by searching for an access server having an empty line, it is possible to determine an access server to which a packet is to be transmitted.

Also, if the network connection device is an ISDN
When sending a packet to an access server to communicate via a public line such as a public network, if there are multiple access servers, the access destination that has a free line is searched for The server can be determined.

In the present embodiment, the case where the packet is transmitted using the IP address of the session layer of the third layer of the OSI reference model has been described, but the same applies to the case where the address of the network layer of the fifth layer is used. This embodiment can be implemented in the following manner.

[0116]

As described above, the following remarkable effects are obtained.

(1) In the present invention, when a LAN terminal communicates via an ISDN network, a line can be used efficiently by searching for an access server with a free line before transmitting a packet. .

(2) The access server is connected L
Since the line connection confirmation packet is transmitted to the AN by broadcasting, it is not necessary to repeatedly transmit the line connection confirmation packet.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration according to a first embodiment of the present invention.

FIG. 2A shows storage locations of respective tables in a LAN terminal and an access server used in the present embodiment;
FIG. 3B is a diagram illustrating a configuration of a routing table, FIG. 3C is a diagram illustrating a configuration of an access server during line connection, and FIG.

FIG. 3 is a diagram showing a portion indicated by an address and a port of each table used in the embodiment.

FIG. 4 is a diagram showing the correspondence between address pointers in each table.

5A is a diagram illustrating processing of a routing table when a line is free, FIG. 5B is a diagram illustrating processing of a routing table and a line-connected access server table when a line is not free, and FIG. It is a figure which shows the processing of the routing table at the time of line connection, and the access server table during line connection.

FIG. 6 is a diagram showing processing of the access server table 32 during line connection when the line is disconnected.

FIG. 7 is a diagram illustrating a frame configuration of a connection / disconnection notification packet transmitted from the line connection / disconnection processing unit of the access server to the network.

FIG. 8 is a diagram showing a description order of the first embodiment of the present invention.

FIG. 9 is a diagram showing a general flow of the operation of the present embodiment.

FIG. 10A is a diagram showing a hierarchy of operations in the flowcharts of FIGS. 11, 12, and 14; FIG.
FIG. 15 is a diagram showing the execution order of the flowcharts of FIGS. 1, 12, and 14.

FIG. 11 is a flowchart showing an operation when the packet output processing unit of the LAN terminal transmits a packet.

FIG. 12 is a flowchart showing the operation of a destination access server search unit of the LAN terminal.

FIG. 13 is a flowchart showing the operation of another embodiment of the destination access server search means.

FIG. 14 is a flowchart showing the operation of the line status confirmation packet response means of the access server.

FIG. 15 is a flowchart showing the operation of the line connection / disconnection processing unit of the access server and the operation of the connection / disconnection notification packet processing unit of the LAN terminal when the line of the access server is connected to the ISDN network;

FIG. 16 is a flowchart showing the operation of the line connection / disconnection processing unit of the access server and the operation of the connection / disconnection notification packet processing unit of the LAN terminal when the line of the ISDN network is disconnected in the access server.

FIG. 17 is a block diagram illustrating a system configuration according to a second example of the present invention.

FIG. 18 is a diagram showing a description order of the second embodiment of the present invention.

FIG. 19 is a diagram showing a general flow of the operation of the present embodiment.

FIG. 20 is a flowchart showing an operation when the packet output processing unit of the network connection device sends out a packet.

FIG. 21 is a flowchart showing the operation of a destination access server search unit of the network connection device.

FIG. 22 is a flowchart showing the operation of another embodiment of the destination access server search means.

FIG. 23 is a flowchart showing the operation of the line status confirmation packet response means of the access server.

FIG. 24 is a flowchart showing the operation of the line connection / disconnection processing unit of the access server and the operation of the connection / disconnection notification packet processing unit of the network connection device when the line of the ISDN network of the access server is connected. .

FIG. 25 is a flowchart showing the operation of the line connection / disconnection processing unit of the access server and the operation of the connection / disconnection notification packet processing unit of the network connection device when the line of the ISDN network is disconnected in the access server. .

FIG. 26 is a diagram showing a conventional system configuration.

[Explanation of symbols]

1,100 LAN terminal 1 ′ Network connection device 2,4,6,7,8,10,11,104,106,1
07, 108, 110, 111 Ports 3, 14, 16, 18, 20, 22, 24, 26, 2
8, 71, 72, 76, 77, 114, 116, 11
8,120 LAN 5,9,105,109 Access server 12,112 ISDN network 13,15,17,19,113,116,118,1
20 ISDN router 21, 23, 25, 27, 70, 75 Host 31, 31 ', 131 Routing table 32, 32' Line connection access table 33, 33 'Destination access server search means 34, 34' Packet output unit 35 , 35 'connection / disconnection notification packet processing unit 36, 36' routing table preparation unit 41 line status confirmation packet response means 42 counterpart management table 43 line connection / disconnection processing unit 44 counterpart management table preparation unit 31a, 32a, 42a, 52 Destination address section 31b Next Hop address section 31c Output port section 32b Access server address section during line connection 42b ISDN router name section 42c Connection port section 50 MAC (Media Access Control) header section 51 IP (Internet Protocol) header section 53 Event section 60 packets Operation of processing unit 61 Operation of transmission destination access server search unit 62 Operation of line status confirmation packet response unit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04M 3/00 H04L 11/20 102D

Claims (7)

[Claims] 1. A destination access server comprising a LAN terminal connected to a LAN and an access server, and searching for an access server having a vacant line when communicating from the LAN terminal via an ISDN network. The determination device, wherein the LAN terminal has a line connection access server table for managing whether a line to which a packet is to be transmitted is connected, and a packet transmission and an idle line to the ISDN network. A destination access server search unit for performing a process of searching for the access server; a packet output processing unit for performing a packet output process; and a connection packet for notifying connection of a line transmitted from the access server and notification of a line disconnection. A connection / disconnection packet processing unit for receiving a line disconnection notification packet
A destination access server determination device characterized by having: 2. The transmission destination access server determining apparatus according to claim 1, wherein said access server responds to an inquiry by a line status confirmation packet to said LAN terminal as to whether or not a line is free. A destination management table that manages the status of use of the line to the destination address; and a line connection / disconnection processing unit that notifies the LAN terminal of connection / disconnection of the line when the line is connected and disconnected. A destination access server determining apparatus characterized by having: 3. The destination access server determining apparatus according to claim 1, wherein the line-connected access server table of the LAN terminal comprises: a destination address portion storing a destination network address or a host address; And a network access server address section during line connection in which the network address of the server is stored. The contents of the address server section during line connection are created from the packet output processing section and the connection / disconnection notification packet processing section. A destination access server determination device characterized by being performed. 4. The destination access server deciding device according to claim 1, wherein the destination management table includes: a destination address part storing a destination network address or a host address; ISDN in which an ISDN router name for connecting an ISDN router connected via the ISDN network is stored.
A router name part; and a connection port part storing a port name or a port number when a line is connected, wherein the contents of the connection port part are created by the line connection / disconnection processing part. A destination access server determining apparatus, characterized in that: 5. A first step of referring to an access server table during line connection to check whether there is an access server connected to a destination network, and in the first step, a destination network If there is no access server connected to the server, a second step of inquiring the access server by the destination access server searching means; and checking the line status in response to the inquiry from the destination access server searching means. A third step of responding by the packet responding means; and a fourth step of, in the third step, receiving a response from the line status confirmation packet responding means and searching the LAN terminal for an access server having a free line. Steps: when a line is connected and disconnected, the line connection / disconnection processing unit sends the LAN terminal Notifies the connection / disconnection of the line in,
A fifth step of confirming the existence of the access server; and a destination access server determining method. 6. An inter-network connection device connected to a LAN and an access server. When communication is performed from said plurality of inter-network connection devices via an ISDN network, an access server having an empty line is used. A destination access server determining device to be searched, wherein the inter-network connecting device has a line connected access server table for managing whether a line is connected, and has a packet output to the ISDN network and a free line. Destination access server searching means for performing a process of searching for the access server which is performing; a packet output processing unit for performing a process of outputting a packet to be transmitted to the ISDN network; and notification of a type of a line transmitted from the access server. Connection / disconnection packet for receiving a connection notification packet to be disconnected and a disconnection notification packet for notifying that the line is disconnected. And Tsu DOO processor, the destination access click server determination apparatus characterized by having a. 7. A first step of checking whether there is an access server connected to a destination network by referring to an access server table during line connection, and in the first step, a destination network If there is no access server connected to the server, a second step of inquiring the access server by the destination access server searching means; and checking the line status in response to the inquiry from the destination access server searching means. A third step of responding by a packet responding unit; and a third step of receiving a response from the line status confirmation packet responding unit in the third step and searching for an access server in which the inter-network connecting apparatus has a free line. Step 4 and when the line is connected and disconnected, from the line connection / disconnection processing unit Notifies the connection / disconnection of the line between the serial network connection device, a fifth to confirm the presence of the access server
And a method of determining a destination access server.