JPH08298523A - Router - Google Patents

Abstract

PURPOSE: To prevent wasteful charging even if the equipment for transmitting/ receiving a keep-alive packet and a keep-alive response packet is erroneously connected to a LAN in a router installed between the LAN and a public exchange network. CONSTITUTION: The local-side router 3 is provided with a function for disconnecting a line on the ISDN exchange network 7 when a transmission packet and a reception packet do not exist for prescribed time. A keep-alive packet filtering means 32 in the local-side router 3 is provided with a function for abolishing the keep-alive packet when it is outputted from a local-side equipment 2 to a remote-side equipment 5. When only the keep alive packet is transmitted from the local-side equipment 2, a system becomes a state where the transmission packet and the reception packet do not exist. When such state continues for a prescribed time, the local-side router 3 disconnects the line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a router installed between a local area network and a public switched network.

[0002]

2. Description of the Related Art Local Area Network (LAN)
And a public switched network such as an ISDN switched network.
Some conventional routers that support the CP / IP protocol disconnect the line when packets are not transmitted / received for a certain period of time to prevent unnecessary charges (for example, "Network configuration device C & C optical network system"). C & C-NET BRANCH4680
II LAN-to-LAN Connection Mechanism Operation Manual, "May 1993, first edition, issued by NEC Corporation, P2-34 to P2-3
6).

In addition, in a conventional device connected to a LAN, a keep-alive packet is sent in order to notify the partner device that the own device is not down and to confirm that the partner device is not down. , There is a device that sends and receives a keep-alive response packet.

A device transmitting and receiving such a keep-alive packet and a keep-alive response packet can notify the partner device that its own device is not down and can confirm that the partner device is not down. However, if the keep-alive packet and the keep-alive response packet are transmitted to the public switched network, the public switched network for exchanging the packets imposes a cost burden. Therefore, the public switched network is routed through the router. Connected to LA
It is common not to connect to N.

[0005]

As described above, it is common not to connect a device for transmitting and receiving keepalive packets and keepalive response packets to the LAN connected to the public switched network via the router. However, such a device may be connected by some mistake.

If such a situation occurs, even if the LAN and the public switched network are connected using a router that disconnects the line when the packet is not transmitted / received for a certain period of time, the keep-alive packet, Since the keep-alive response packet flows, the line is not disconnected, and there is a problem that useless billing is performed.

Therefore, an object of the present invention is to prevent unnecessary charging even if a device for transmitting and receiving a keepalive packet and a keepalive response packet is erroneously connected to the LAN. To provide a router.

[0008]

In order to achieve the above-mentioned object, the present invention is installed between a local area network and a public switched network, and a packet to be routed is transmitted from a device connected to the local area network. In the router that connects the line when the packet is transmitted and disconnects the line when the packet is not transmitted / received for a certain period of time, the device has a keep-alive packet filtering means for discarding the keep-alive packet transmitted from the device connected to the local area network. It is a thing.

[0009]

When the keep-alive packet is transmitted from the device connected to the local area network, the keep-alive packet filtering means of the router discards it. Therefore, in the state where only the keep-alive packet is transmitted from the device connected to the local area network, the line will not be disconnected and wasteful charging will not be performed.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which a local LAN 1 to which a local device 2 is connected.
And the remote LAN 4 to which the remote device 5 is connected
, A local router 3 connecting the local LAN 1 and the ISDN switching network 7, a remote LAN 4 and an ISD
It is composed of a remote side router 6 which connects to the N-switching network 7.

Local router 3 and remote router 6
Comprises LAN control means 31, 61, keep-alive packet filtering means 32, 62, and line connection means 33, 63, respectively.

The LAN control means 31, 61 include a local side router 3, a remote side router 6 and a local side LAN 1,
It has a function for connecting to the remote side LAN 4.

The keep-alive packet filtering means 32 and 62 are comprised of the local device 2 and the remote device 5.
A function of discarding a keep-alive packet that the device has attempted to send to the partner device via the ISDN exchange network 7, and a keep-alive packet that the local device 2 and the remote device 5 attempt to send to the partner device via the ISDN exchange network 7. Other than ISD via the line control means 33, 63
It has a function of transmitting to the N switching network 7.

When the packet is passed from the keep-alive packet filtering means 32 or 62 while the line is not connected to the partner router, the line controller 33 or 63 connects the line and sends the packet to the partner router. Keep-alive packet filtering means 3 with the function of transmitting and the line connected to the partner router
When a packet is passed from 2, 62, the function to send the packet to the other router through the already connected line, the function to disconnect the line when the packet is not sent and received with the other router for a certain period of time, etc. Have.

FIG. 2 is a diagram for explaining the operation of this embodiment. The operation of this embodiment will be described below with reference to the drawings.

When the local device 2 sends the SYN packet to be transmitted to the remote device 5 to the local LAN 1, the LAN control means 31 in the local router 3 receives the SYN packet (S21).

In the keep-alive packet filtering means 32, when the LAN control means 31 receives a packet, it judges whether or not it is a keep-alive packet, discards it if it is a keep-alive packet, and discards it if it is not a keep-alive packet. It is passed to the line control means 33. In the case of this example, since the packet received by the LAN control means 31 is a SYN packet, the keep-alive packet filtering means 32 regards it as the line control means 3.
It will be passed to 3.

When the packet is delivered, the line control means 33 judges whether or not the line is connected to the remote side router 6 corresponding to the remote side device 5 of the destination of the packet, and if not connected. After connecting the line, the packet is transmitted to the remote side router 6, and if connected, the packet is transmitted to the remote side router using the already connected line. If the line is not connected now, the line control means 33 performs a line connection operation to connect the local side router 3 and the remote side router 6 to each other.
Connection is made via the SDN exchange network 7, and then a SYN packet is transmitted to the remote side router 6 via the ISDN exchange network 7 (S22, S23).

When the remote-side router 6 receives the SYN packet, it sends it to the remote-side device 5, and when the remote-side device 5 receives the SYN packet, it sends a SYN-ACK packet as a response thereto (S
24, S25). This SYN-ACK packet is sent to the local device 2 via the remote router 6, the ISDN switching network 7, the local router 3, and the local LAN 1 (S25 to S27).

Upon receiving the SYN-ACK packet, the local device 2 outputs a (DATA + PUSH) packet containing data to be transmitted to the remote device 5 to the local LAN 1 (S28).

This (DATA + PUSH) packet is
It is sent to the remote-side device 5 via the local-side router 3, the ISDN switching network 7, and the remote-side router 6 (S29, S
30), an ACK packet as a response thereto is sent to the local device 2 via the remote router 6, the ISDN switching network 7, and the local router 3 (S31 to S3).
3).

Now, assuming that the local device 2 is a device having a function of transmitting and receiving keepalive packets and keepalive response packets, if there is no data to be transmitted to the local device 2 after receiving the ACK packet, A keep-alive packet is sent to the remote device 5 (S41 to S47).

This keep-alive packet is received by the LAN control means 31 of the local side router 3, but since it is a keep-alive packet, it is discarded by the keep-alive packet filtering means 32 and is not passed to the line control means 33. Therefore, the line control means 33
Becomes a state in which neither packet is transmitted nor received, and when this state continues for a certain period of time, the line control means 33 performs a line disconnection operation to disconnect the line between the local side router 3 and the remote side router 6 (S51). ).

After that, when data to be transmitted to the remote side router 6 is generated, the local side device 2 sends a (DATA + PUSH) packet containing the data to the remote side device 5 (S61).

This (DATA + PUSH) packet is
Since it is not a keep-alive packet, it is received by the LAN control means 31 and then passed to the line control means 33 by the keep-alive packet filtering means 32.

Since the line between the local side router 3 and the remote side router 6 is currently in a disconnected state, the line control means 33 connects the line (S62),
Then, the (DATA + PUSH) packet is transmitted to the remote router (S63).

[0028]

As described above, the router of the present invention is
Keep-alive packet filtering means that discards keep-alive packets sent from devices connected to the local area network is provided to prevent keep-alive packets from being sent and received over the public switched network. Even if a device that transmits and receives the alive packet and the keepalive response packet is erroneously connected, the keepalive packet does not prevent the disconnection of the line, and as a result, it is possible to prevent wasteful billing.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment of the present invention.

[Explanation of symbols]

 1 ... Local side LAN 2 ... Local side device 3 ... Local side router 31 ... LAN control means 32 ... Keep alive packet filtering means 33 ... Line control means 4 ... Remote side LAN 5 ... Remote side device 6 ... Remote side router 61 ... LAN Control means 62 ... Keep-alive packet filtering means 63 ... Line control means 7 ... ISDN switching network

Claims (3)

[Claims] 1. A line is connected when a packet to be routed is transmitted from a device connected to the local area network and is installed between a local area network and a public switched network, and the packet is not transmitted or received for a certain period of time. A router for disconnecting a line, comprising: keep-alive packet filtering means for discarding a keep-alive packet transmitted from a device connected to the local area network. 2. The keep-alive packet filtering means transmits packets other than keep-alive packets transmitted from a device connected to the local area network to the public switched network. Router. 3. The router according to claim 2, wherein the public switched network is an ISDN switched network.