JPS62107555A - Inter-network connection equipment - Google Patents

Abstract

PURPOSE:To improve the operability and fault immunity as a system, to attain the easiness of expansion/change and to reduce the communication cost by connecting an inter-network connection equipment via two kinds of relay means as a packet exchange network and a private line. CONSTITUTION:In receiving a call request from a local area network LAN, the inter-network connection equipment GW branches the processing depending on the presence of private line connection to an incoming side LAN. In case of the connection by a private line, a call request packet is sent to the private line when the call is enabled to request the setting of connection till the incoming terminal equipment to the incoming side GW. In case of the connection to the incoming side LAN not by the private line, when the call setting via the private line is failed, a call request packet to the incoming side GW is sent to the packet exchange network. Whether or not the call setting is finished is discriminated by the reception of the incoming call packet from the incoming side GW.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a local area network (hereinafter referred to as LA) using a packet switching network and a dedicated line as a relay route.
[Prior art] Network interconnection equipment (hereinafter referred to as GW), which has been researched and announced as a means of expanding the area of LAN, connects a LAN and another LA located in a remote location, N The following three types of communication formats have been considered in order to realize mutual communication with

(a) Communication form in which LANs are interconnected via a dedicated line (b) Communication form in which LANs are interconnected via a packet switching network (1) Communication form in which LANs are interconnected via a circuit switching network Figure 10 , Figures 11 and 12 show (a) and (, respectively).
B).

(/indicates each communication form.

To relay mutual communication between LANs, (a), ←), e
) A conventional GW that uses only one type of communication form is called a single-type GW, and the single-type GW has the following drawbacks.

(1) Since one GW has only one type of relay path, even if a failure occurs in this relay path, a reliable alternative relay path cannot be secured. Furthermore, even if a backup line is set up in addition to the regular line in (a) to secure an alternative relay route, and the line is switched to use in the event of a failure, communication costs will increase due to the usage fee for the backup line.

(2) From the point of view of communication costs, GW in (B) is suitable for short-distance, high-traffic LAN-to-LAN communication;
For low traffic LAN communication (b).

GW of RL is suitable. However, by using a single GW, it is possible to realize six types of communication (A), (B), and (B) through the same LAN.
In order to realize this, it is necessary to accommodate a plurality of LANs that serve as relay paths within the LAN, and it is necessary to expand system functions such as a GW selection function within the LAN and increase equipment.

(3) In a system using only one type of single-type GW,
Communication form (a) has the disadvantage that it cannot flexibly deal with network expansion and changes, and that the number of LANs with which mutual communication can be performed is limited by the number of dedicated lines that can be connected to the GW.

[Problem that the invention seeks to solve]

That is, since the conventional single-type GW has a single relay means, there are problems in operability and fault tolerance, and a flexible network configuration is not possible.

This invention was made to solve the above-mentioned problems, and aims to provide a flexible network configuration at low cost and to obtain a nine-GW network with excellent operability and fault tolerance.

[Means to Solve the Problem] The GW according to the present invention connects to different relay paths, a dedicated line and a packet switching network, using the same device, and always uses the two relay paths simultaneously in normal operation mode. This realizes the selection of a relay route for each call or each causer data packet by placing the relay path in a possible state.

[Effect]

Since the GW according to the present invention is equipped with two different types of relay paths, it is possible to configure a flexible network according to the LAN arrangement and inter-LAN traffic (1), and by selecting the relay path for each call. Call settings can be made reliably even in the event of line failure 9 congestion, and if the function has a relay route selection function for each user data packet, the relay route can be changed without disconnecting the call even in the event of a failure. can.

[Embodiments of the invention]

FIG. 1 shows a system configuration of an embodiment of the present invention. In the first factor, (IIL) and (lb) are each LAN
, (2a) and (2b) are network connection devices (GW) that are used to widen the LAN, and (3a) and (3b) are LAN
nodes for accommodating terminals, (4a), (4b),
(4c) is a terminal that accommodates LANK, (5) Company's GW above
(2a), (2b) connected packet switching networks, (6
) is a dedicated line that directly connects the GWs (2a) and (2b).

As shown in FIG. 1, the GWs (2a) and (zb) are two of the packet switching network (5) and the dedicated line (6).
For example, in communication across a LAN, such as the communication between the terminals (4a) and (4b), the above (5) and (6) can be used as relay routes to transfer data between terminals. , (5) and (6) for each call or packet according to line conditions such as failures and congestion.
) can be used as a relay route.

FIG. 2 shows an example of the hardware configuration of the GW that implements the relay route selection function. In Figure 2, the wire is an optical fiber that forms the transmission path of the LAN, Ql) is a photoelectric conversion unit that performs mutual conversion between optical signals and electrical signals, and transmits and receives packets on the optical fiber, and (2) is the optical fiber that forms the LAN transmission path. A LAN packet access unit that executes layer 2 and layer 3 protocols of packet switching procedures, (to) a protocol conversion unit that performs mutual conversion between LAN internal protocols and packet switching network connection protocols, and 04 that performs protocol conversion such as terminal addresses. The disk unit that stores necessary information (to) is the main memory unit, αQ is the main control unit that is in charge of system operation management, and α is the line control unit 1 that executes the connection protocol with the packet switching network (to). ) is the interface to the packet switching network, α is the line control unit 2 that executes the connection protocol with the dedicated line, and (a) is the interface to the dedicated line.

In FIG. 2, communication between terminals via the GW is a mouse.

(b), (2), (to), communication via a packet switching network, or nl'I1. aη, Q, (Ll, αcast, (a)) is realized as communication via a dedicated line.Here, the relay route selection function of the GW is placed in the above (to) protocol conversion unit, and its In execution, the above Q4 disk unit and the above Qfi
l The relay path connection status seen in the main memory unit,
Refers to information such as the relay route operating status and the line control unit number for the relay route.

FIG. 3 shows an example of the GW software configuration created according to the hardware configuration example shown in FIG.

In Figure 3, 0◇ is a layer 2 execution module for intra-LAN packet exchange procedures, 2) is a layer 3 execution module for intra-LAN packet exchange procedures, and 2) is an intra-LAN packet exchange procedure and packet exchange network connection protocol or dedicated line. A protocol conversion module that performs mutual protocol conversion with a connection protocol, (Foundation) is a layer 3 execution module of a packet-switched network connection protocol, (To) is a layer 2 execution module of a packet-switched network connection protocol, (To) is a dedicated line Layer 3 execution module of connection protocol, (b) Layer 2 execution module of dedicated line connection protocol, (to) operation management module in charge of managing GW operating status, maintenance of protocol conversion information, etc., and man-machine interface, (To) is a real-time monitor that monitors and controls the execution of each module from (B) to (To) above, Sakaki is an interface to LAN, θ is an interface to a packet switching network, and (6) is an interface to a dedicated line. It is an interface. The packet-switched network connection module in (B) and (to) above and the dedicated line connection monthly module in (to) above and @ use the same program. )1. It is placed in the Q'J line control unit 2. Processing contents that differ depending on the protocol for connection to a packet-switched network or for dedicated line connection are executed by the program identifying differences in GW operation management information such as relay path connection status. The protocol conversion module shown in (to) above is placed on the protocol conversion unit shown in FIG. have

Below, the processing flow of the GW with the relay route selection function for each call,
The call setup procedure will be explained.

In Fig. 4, when the GW connected as in (21L) e (21:l) above receives a call request from a terminal within the LAN, it connects to the packet switching network (5) or the dedicated line (6).
The flowchart shows a series of processes from sending a calling packet to the GW of the destination LAN via the GW to establishing or disconnecting the call. In Figure 4, from (1,00) to (111
) is each processing step.

When the OW receives a call request from a terminal within the LAN, in step (:LOO) it determines whether there is a dedicated line connection to the destination LA, N, and if it is connected to a packet switching network, from the destination LAN address in the call request. Search for information such as the address in the packet switching network of the other party's GW, and in step (101) branch the process depending on whether or not there is a dedicated line connection to the destination LAN. ) line failure,
Check whether the dedicated line is in a state where it is possible to make a call, such as when the other party is busy, and if it is possible to make a call, a call request packet is sent over the dedicated line in step (103), and the call is sent to the destination GW to the destination terminal. request connection settings. Next, in step (104), it is determined whether or not the call setting is completed by receiving an incoming call packet within a certain period of time, and if it is completed, the logical channel number address conversion of the call set in step (105) is performed. Call setting information necessary for data transfer such as information below is set in a call control table in which this information is set for each call via OW, and further, in step (106), L
It notifies the originating terminal within the AN that the connection is complete, completes the call connection between the terminals, and enters the data transfer state. On the other hand, step (10
:L), if there is no connection to the destination LAN via a dedicated line, and if call setup via the dedicated line fails in step (1o2) or step (104), proceed to step (10').
? ), it is checked whether it is possible to make a call to the packet switching network due to a line failure or the like, and in step (10B), a call request packet to the destination GW is sent to the packet switching network. Then, in step (109), it is determined whether the υ call setup is completed by receiving the incoming call packet from the destination GW, and if the call setup is complete, the above steps (lo5) and (1o1 are performed). , and if the call setup fails, step (110
), the call disconnection notification is sent to the originating terminal to notify the failure of the call.

FIG. 5 shows a flowchart of call processing at the destination GW that receives a call from the originating GW via the packet switching network or dedicated line. In FIG. 5, (111) to (1115) are each processing step, and in step (111), the destination GW sends the receiving subaddress from the originating GW to the address of the destination terminal within the destination LAN. and sends an incoming call packet to it. Next step (1
In step 12), it is determined whether or not the call has been successfully received by receiving a connection completion packet from the destination terminal within a certain period of time, and if the call has been successfully received, call setting information is set in the call control table in step (113). , in step (114), transmits a connection completion packet to the originating GW and enters the data transfer state.

On the other hand, if the incoming call fails in step (112), the destination GW sends a disconnection packet to the originating GW in step (115) to notify the call setup failure. The call setting procedure between networks is shown in FIG. 7, and the call setting procedure between CiWs interconnected by a dedicated line is shown in FIG. Both FIGS. 6 and 7 have the same reference numerals as corresponding parts in the system configuration example shown in FIG. 1, and show the case where the terminals (4a) and (4b) are packet-type terminals. In FIGS. 6 and 7, (120) is a call request packet, (121) is an incoming call packet, (122) is an incoming call reception bucket), (123
) indicates a connection completion packet. In the figure, (x2oa), (
Lowercase letters appended to the same number, such as 1gob) and (12oc), indicate whether the terminal-LAN
It represents the distinction between packets on each interface between nodes, between LAN nodes and GW, and between GW and packet switching network.

The above LAN nodes (3a), (sb) and GW (4
a) and (41)) convert the packet format and packet header contents in accordance with these interfaces.

The format of the above call request bucket (120c) that the GW sends onto the packet switching network and dedicated line is
9 and 9. In Figures 8 and 9, (1
30) complies with International Telegraph and Telephone Advisory Committee (OCT) Recommendation X, 25K and makes 9 calls! packet header of the requested packet, (131) is the DTE address as a terminal accommodated in the packet switching network (5) of the GW (21), (132) is the DTE address of the 0W (2a), ( 133) is the called subaddress of the called terminal (4b) set in the call user data field, (134) is the calling subaddress of the calling terminal (4a), and (135)
indicates that the packet is a call request packet via a dedicated line.
36) is also the dedicated line address in (2a) above.

When the originating GW (2a) receives the call request from the terminal (4a) and sends the call request bucket (1200), it sets up the call according to the flowchart shown in FIG. At this time, the call request packets sent to the packet switching network or dedicated line have almost the same contents as shown in FIGS. 8 and 9, so that the processing at the destination GW (2b) can be shared.

Furthermore, the call setup process at the destination GW (2b) is shown in the flowchart in Figure 5, but the difference between the relay route, the packet switching network and the dedicated line, is set in the call control table and is referenced during subsequent data transfer. .

For an explanation of the above GW processing flow and call setup procedure, please refer to LA.
This is a case where the terminals (4a) and (4b) accommodated in N are packet-type terminals. If one or both of the terminals are non-packet type terminals, the GW in the above explanation
and the terminal order within the LAN is the GW and the P placed within the LAN.
It can be considered as a procedure between the AD (packet disassembly/assembly) function.

In addition, in the above explanation, it is assumed that the GW has only a relay route selection function for each call, but in addition, the GW has a relay route selection function for each user data packet, which is a group of data transferred between terminals, as described below. Let's make it happen. In other words, the terminal (4a) via the GW (ga) and (2b)
, (4b), GW(”a) +
(2b) Two connections, one through the packet switching network and the other through the dedicated line, are set up, and one of the connections is selected as a relay path for each user data packet. With this, even if a line failure occurs on the relay path, the other connection can be used as the relay path, so data transfer can continue.

〔Effect of the invention〕

As described above, according to the present invention, GWs are connected via two types of relay means, a packet switching network and a dedicated line, so even if a failure or congestion occurs in one of the relay means, the call being relayed will be terminated. Moreover, since the same protocol is used on the relay route, it is easy to switch the relay route and control the GW during call setup, which improves system operability and fault tolerance, facilitates expansion and modification, and reduces communication costs. is effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the system configuration of an embodiment of this invention, FIG. 2 is a block diagram showing the hardware configuration of one embodiment of this invention, and FIG. 3 is a block diagram showing the software configuration of the same embodiment. Figure 4 is a flowchart showing an example of the process flow when setting up a call at the originating GW, Figure 5 is a flowchart showing an example of the process flow when setting up a call at the destination GW, and Figure 6 shows how the GW connects the packet switching network. An explanatory diagram showing the call setup procedure when the GW uses the dedicated line as a relay route. Figure 7 is an explanatory diagram showing the call setup procedure when the GW uses a dedicated line as a relay route. Figure 8 is an explanatory diagram showing the call setup procedure when the GW uses a dedicated line as a relay route. An explanatory diagram showing an example of the format of a call request packet. FIG. 9 is an explanatory diagram showing an example of the format of a call request packet sent by the GW to a dedicated line. FIG.
FIG. 11 is an explanatory diagram showing the communication form of LAN; FIG. 11 is an explanatory diagram showing the communication form of LAN-packet switching network-LAN;
The figure is an explanatory diagram showing the communication form of LAN-circuit-switched network-LAN.In figure 0, (1) is a local area network, (2) is an inter-network connection device, (4) is a terminal, and (5) is a local area network.
is a packet switching network, and (6) is a dedicated line. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) In an inter-network connection device (hereinafter referred to as GW) that interconnects local area networks (hereinafter referred to as LAN), the GW serves as a relay route between LANs and includes an interface that connects to a packet switching network and an interface that connects to a dedicated line. On the interface that simultaneously accommodates Ace and connects to the packet-switched network, communication is performed in accordance with communication control procedures that comply with CCITT Recommendations X and 25. In response to the call request from the originating terminal, a call request packet is sent to the packet switching network interface to request call setup to the destination GW, and the destination GW transfers the incoming call packet from the packet switching network interface to the destination terminal. It also converts the incoming call acceptance from the destination terminal into an incoming call acceptance packet to the packet switching network interface, sets the call connection information, and then completes the connection from the packet switching interface at the originating GW. Call connection information is set by converting the packet into a notification of connection completion to the originating terminal, but the same communication control procedure as that on the packet switching network interface described above is used on the interface connected to the dedicated line. In particular, when setting up an inter-network connection call, the destination GW of two GWs connected by a dedicated line converts a call request packet received from the originating GW into an incoming call packet at the packet-switched network interface. In addition, the originating GW regards the incoming call acceptance packet received from the terminating GW as a connection completion packet at the packet switching network interface, thereby realizing the same communication control procedure and controlling the inter-network connection call from the terminal. An inter-network connection device that selects either a packet switching network or a dedicated line as a relay route for an inter-network connection call from an originating GW to a terminating GW for each call request. (2) In response to a request for an inter-network connection call from a terminal, the calling party
W sends a call request packet to both the packet-switched network interface and the dedicated line interface to secure two intermediate routes, one via the packet-switched network and the other via the dedicated line, as relay routes for inter-network connection calls. By making it possible to select a relay route for each set of data collected in packets during data transfer between GWs, connected calls can be maintained even if one relay route becomes unavailable due to a line failure or other reason. Claim 1 characterized in that data transfer is continued using the other relay path without disconnecting the relay path.
Inter-network connection device described in Section 1. (3) Operation management information or communication control procedures for accommodating each interface of the packet switching network and the dedicated line in a device using the same hardware and software, and for the maintenance personnel to set whether the network is the packet switching network or the dedicated line during operation. 2. The inter-network connection device according to claim 1, wherein the device itself identifies itself from information obtained by executing the above, and uses a packet switching network and a dedicated line as a relay path.