JP3595655B2 - Network connection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a network connection device used for a network system such as a LAN (Local Area Network) and a WAN (Wide Area Network).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a network device operating in a network environment based on NetWare, in order to receive the service of NetWare, the network device first needs to temporarily connect to an indefinite server, and recognizes a physical route of the server. It is not possible.
On the other hand, a network is generally divided into a certain size (unit) to form a sub-network, and the plurality of sub-networks are connected by a relay device called a router.
The network to which the router is connected may be a LAN such as Ethernet, a dedicated line, an ISDN line, or the like. A device that relays a LAN and an ISDN line is called an ISDN router.
[0003]
[Problems to be solved by the invention]
By the way, in the case of the ISDN line, the communication fee is a pay-as-you-go system, and if a connection is made via the ISDN line, the communication carrier will be charged.
Therefore, it is desirable not to access the server connected via the ISDN line.
[0004]
Therefore, an object of the present invention is to provide a network connection device that can prevent connection of a server via an ISDN line.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, when a plurality of sub-networks are connected by a router, at least one of the sub-networks is connected to an ISDN line, and when a network device connects to the server, an indeterminate server is connected. Detecting means for detecting a server which does not relay a router in a communication path to the temporary connection destination in a network system requiring temporary connection to the temporary connection destination of the network device. The above object is achieved by providing a selecting means for selecting as.
[0006]
According to the second aspect of the present invention, when a plurality of sub-networks are connected by a router, at least one of the sub-networks is connected to an ISDN line, and when a network device connects to the server, an indeterminate server is connected. Setting means for arbitrarily setting the number n of routers permitted to be connected to the network device in a network system requiring temporary connection to the network device, and storage means for storing the number n of routers set by the setting means Determining means for determining whether or not the number of router steps through the communication path to the temporary connection destination is equal to or less than the number of router steps n stored in the storage means; Is determined to be n or less, the number of stages of the router is n or less as a temporary connection destination of the network device. By providing the selecting means for selecting a server that belongs to blanking network, to achieve the above object.
[0007]
According to the third aspect of the present invention, a plurality of sub-networks are connected by a router, and at least one of the sub-networks is connected to an ISDN line. Setting means for setting an address X of a router which is not permitted as a connection path of the network device in a network system which requires a temporary connection to the network device; storage means for storing the address X of the router set by the setting means; Determining means for determining whether or not the address of the router passing through the communication path to the temporary connection destination matches the address X of the router stored in the storage means; and the determining means determines that the two addresses match. Is determined as the temporary connection destination of the network device, Through the router other than the scan X routers by having a selection means for selecting a server, to achieve the above object.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a network connection device of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a configuration of a network system to which the first embodiment of the present invention is applied.
In this network system, as shown in FIG. 1, a network device (A1) is connected. This network device (A1) has a communication function with another terminal in the network to which it is connected.
The network device (A1) operates for a NetWare network and communicates with a NetWare server. One or more NetWare servers exist in the network, such as NetWare servers (NW1 to 3).
[0009]
This network is divided into a plurality of sub-networks as shown in the figure, and the divided sub-networks are connected by routers (R1, R2) which are relay devices. Further, one of the sub-networks is connected to another sub-network via an ISDN router (IR1), an ISDN line, and an ISDN router (IR2).
The network device (A1) has a NetWare connection function and requires access to a NetWare server for its operation. “NW2” is specified as the preferred server name.
[0010]
Next, prior to describing a procedure for initializing a network having such a configuration, a conventional initialization procedure will be described with reference to a flowchart of FIG.
(1) First, the network device (A1) searches for a server to be provisionally connected by using the Get Nearest server. That is, a request for Get Nearestserver is requested by broadcast transmission (step 1), and if there is a response (step 2; Y), the server of the first response is regarded as the nearest server (step 3).
(2) A connection is established with the nearest server obtained in (1), and initialization necessary for the connection is performed (step 4).
[0011]
(3) Using the nearest server, search for the preferred server "NW2" (steps 5 and 6). Thereby, the address of the preferred server is obtained.
(4) As a result of the search in (3), the preferred server "NW2" exists, and if the address is successfully obtained, the user logs in to the preferred server "NW2" (step 7).
(5) If the login is successful in (4) (Step 8; Y), the main purpose operation of the network device (A1) is performed. For example, if the network device (A1) is a print server, the print server polls the print job from the preferred server "NW2", and prints out if it exists.
[0012]
Here, the problem is that it is unclear where the nearest server, which is a temporary server required when searching for a preferred server, will be.
This is because the server that is physically close is not recognized, but is determined by the order in which the response packets are received on the network device (A1) side (see FIG. 8). Here, the response beyond the router is not made by the server itself but by the router. Normally, the router always caches server information, and answers Get Nearest Server immediately.
[0013]
Therefore, there is a possibility that the preferred server “NW3” connected via the ISDN line may be obtained.
Also in this case, the network device (A1) connects to the server NW3 in the above procedure (2). By this operation, the router (R1) makes a call to the router (R2) to make a connection.
If the ISDN line is charged on a pay-as-you-go basis, a charge will be incurred at this time.
In the case where the preferred server does not exist, in the case of an apparatus that retrys, the connection with the nearest server is continued until the preferred server is found.
As can be seen from the above, in the conventional method, only the response that has arrived earliest among the responses of the Get Nearest Server has been adopted.
[0014]
Therefore, in the first embodiment of the present invention, the procedure for initializing the network is performed as follows. FIG. 2 is a flowchart showing the initialization procedure.
First, the network device (A1) issues a "Get Nearest Server" request by broadcasting, receives a response to the request for a predetermined t seconds, and converts the packet received during the t seconds into a packet shown in FIG. Are recorded in the server table T1 (steps 11 to 14). Since the received packet includes the server name, the server address, and the hop number, these pieces of information are recorded in the table T1.
The time-out process for t seconds is performed in consideration of no response (there is no NetWare server) for reception.
[0015]
When a timeout occurs after elapse of t seconds (step 12; Y), it is determined whether there is one or more servers (step 15). If the result of this determination is that there is at least one server (step 15; Y), as shown in FIG. 3B, the order of the servers in the table T1 is rearranged in ascending order of the number of hops (step 16). ). Here, the number of hops refers to the number of stages (number) of routers that pass through.
After rearranging the order of the servers, the server refers to the record that is the first entry and regards it as the nearest server. That is, it is determined whether or not the hop number of the first record is “0” (step 17). If the hop number is “0”, the server recorded in the first record is regarded as the nearest server (step 18). ).
In this example, the server (NW1) is always regarded as the nearest server. Since the number of hops of this nearest server is “0”, this server is a server that never crosses a router, and does not call the ISDN.
[0016]
When the connection with the nearest server is established in this way (step 19), normal processing is continued.
In other words, the preferred server is searched using the nearest server (step 20), and as a result of the search, if the preferred server exists (step 21; Y), the user logs in to the preferred server (steps 22 and 23).
[0017]
Next, a second embodiment of the present invention will be described.
In the network of FIG. 1, it is assumed that there is no NetWare server (NW1) connected to the same subnetwork as the network device (A1). In this case, since the network device (A1) wants to use the NetWare server (NW2) as a preferred server, the existence of the NetWare server (NW1) is essentially unnecessary.
However, in the first embodiment, the network system will not operate because the operation requirement is that the NetWare server always exists at the hop number “0” as described above.
On the other hand, if there is an administrator who fully understands the configuration of the network in FIG. 1, it is clear that there is no NetWare server that passes through the ISDN router even when the hop count is within “1”.
[0018]
Therefore, in the second embodiment, the upper limit value of the number of hops when determining the nearest server is made variable, and the number of hops can be set by the user, and the hop number can be set and stored. is there.
Here, the upper limit of the number of hops preset by the user is “n”. Then, when there is a server whose hop number is equal to or less than “n”, the server is regarded as the nearest server and the processing is continued.
[0019]
Next, a network initialization procedure according to the second embodiment will be described with reference to the flowchart in FIG.
First, the upper limit value n of the number of hops set by the user and stored in advance is read (step 31).
Next, after the network device (A1) issues a “Get Nearest Server” request by broadcast, a response to the request is received for a predetermined t seconds, and the packet received for the t seconds is recorded in the server table. (Steps 32 to 35). Since the received packet includes the server name, the server address, and the number of hops, these pieces of information are recorded in the server table.
[0020]
When a timeout occurs after elapse of t seconds (step 33; Y), it is determined whether there is one or more servers (step 36). If the result of this determination is that there is at least one server (step 36; Y), the server order in the server table is rearranged in ascending order of hop count (step 37).
After rearranging the order of the servers, it is determined whether or not the number of hops of the first record is equal to or less than "n" (step 38). It is regarded as a server (step 39).
Thus, when the connection with the nearest server is established (step 40), the normal processing is continued. That is, the preferred server is searched using the nearest server (step 41), and if the preferred server exists as a result of the search (step 42; Y), the user logs in to the preferred server (steps 43 and 44).
[0021]
Next, a third embodiment of the present invention will be described.
FIG. 5 is a diagram showing an example of a configuration of a network system to which the third embodiment is applied.
In this network system, as shown, a subnetwork including a network device (A1) is connected to another subnetwork via an ISDN router (IR1), an ISDN line, and an ISDN router (IR2).
Further, a setting item “excluded router” is provided for the network device (A1), and the node address value of the router can be stored therein.
Here, the ISDN router (IR1) in FIG. 5 is a target of the excluded router. Therefore, the address “X” of the ISDN router (IR1) is set and stored in the network device (A1) as the “excluded router”.
[0022]
Next, an initialization procedure according to the third embodiment having such a configuration will be described with reference to the flowchart in FIG.
First, the network device (A1) issues a “Get Nearest server” request (step 51), and upon receiving the response, sets the source address of the response packet to the registered “excluded router” address “ X "(steps 52 and 53).
As a result of this comparison, when the value of the source address matches the registered “excluded router” address “X” (Step 54; Y), this packet is discarded and another packet is received.
On the other hand, when the value of the source address does not match the registered address "X" of the "excluded router" (step 54; N), the response packet is validated.
Here, the valid response packet is the earliest one other than the “excluded router”, but one may be extracted from the response packets from other than the “excluded router”.
[0023]
Next, the server stored in the valid response packet is regarded as the nearest server (step 55).
Thus, when the connection with the nearest server is established (step 56), the normal processing is continued. In other words, the preferred server is searched using the nearest server (step 57), and as a result of the search, if the preferred server exists (step 58; Y), the user logs in to the preferred server (steps 59 and 60).
[0024]
【The invention's effect】
According to the first aspect of the present invention, a server that does not relay the router in the communication path to the temporary connection destination is detected, and the detected server is selected as a temporary connection destination of the network device. For this reason, connection with the server via the ISDN can be prevented.
[0025]
According to the second aspect of the present invention, it is possible to arbitrarily set and store the number n of routers permitted to connect to the network device, and to store the number of routers passing through the communication path to the temporary connection destination. When it is determined that the number of stages of the router is n or less, a server belonging to a subnetwork having the number of stages of the router of n or less is selected as a temporary connection destination of the network device. For this reason, connection with the server via the ISDN can be prevented.
[0026]
According to the third aspect of the present invention, it is possible to set and store the address X of a router that is not permitted as a connection route of the network device, and to set the address of the router that passes through the communication route to the temporary connection destination with the stored router address. When the address X coincides with the address X, a server passing through a router other than the router having the coincident address X is selected as a temporary connection destination of the network device. For this reason, connection with the server via the ISDN can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a network system to which a first embodiment of the present invention is applied;
FIG. 2 is a flowchart illustrating a network initialization procedure according to the first embodiment.
FIG. 3 is a diagram illustrating an example of contents stored in a server table;
FIG. 4 is a flowchart illustrating a procedure for initializing a network according to a second embodiment;
FIG. 5 is a diagram illustrating an example of a configuration of a network system to which a third embodiment of the present invention is applied;
FIG. 6 is a flowchart illustrating a network initialization procedure according to the third embodiment.
FIG. 7 is a flowchart showing a conventional network initialization procedure.
FIG. 8 is a diagram illustrating an example of a Get Nearest Server sequence.
[Explanation of symbols]
A1 Network device NW1-3 NetWare server R1, R2 Router IR1, IR2 ISDN router

Claims (3)

A plurality of sub-networks are connected by a router, at least one of the sub-networks is connected to an ISDN line, and a temporary connection to an indeterminate server is required when the network device connects to the server. In network systems,
Detecting means for detecting a server that does not relay a router in a communication path to the temporary connection destination;
Selecting means for selecting a server detected by the detecting means as a temporary connection destination of the network device;
A network connection device, comprising: A plurality of sub-networks are connected by a router, at least one of the sub-networks is connected to an ISDN line, and a temporary connection to an indeterminate server is required when the network device connects to the server. In network systems,
Setting means for arbitrarily setting the number of stages n of the router that permits connection with the network device;
Storage means for storing the number of router stages n set by the setting means;
Determining means for determining whether or not the number of stages of the router passing through the communication path to the temporary connection destination is equal to or less than the number of stages of the router n stored in the storage means;
When the determination unit determines that the number of stages of the router is n or less, a selection unit that selects a server belonging to a subnetwork whose number of stages of the router is n or less as a temporary connection destination of the network device;
A network connection device, comprising: A plurality of sub-networks are connected by a router, at least one of the sub-networks is connected to an ISDN line, and a temporary connection to an indeterminate server is required when the network device connects to the server. In network systems,
Setting means for setting an address X of a router not permitted as a connection path of the network device;
Storage means for storing the router address X set by the setting means;
Determining means for determining whether or not an address of a router passing through a communication path to a temporary connection destination matches an address X of the router stored in the storage means;
When the determining means determines that the two addresses match, selecting means for selecting a server passing through a router other than the router having the matching address X as a temporary connection destination of the network device;
A network connection device, comprising:

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