JP2000307590A - Connection establishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high-speed communication and to reduce the device cost on the side of a client. SOLUTION: An NHC-A 12 transmits a solving request packet to an NHS-A 14 and when an IP address C2 is not under its control, transmits the solving requesting packet to an NHS-C 16 of a next hop destination. When the address C2 is under control of the NHS-C 16, the resource Vc of an NHC-C 18 is obtained. The NHS-C 16 prepares a solution responding packet based on an address Nb and the resource Vc to respond to the NHS-A 14, which extracts Nb and Vc from the solution responding packet. The NHS-A 14 issues signaling by Vc to Nb of the NHS-C 16 and an LIS-B 22 validates Vc. The NHS-A 14 prepares the solution responding packet by Vc to respond to the NHC-A 12. Vc is also validated also in an LIS-A 20. The NHC-A 12 extracts Vc from the solution responding packet and transmits an IP packet directly to an NHC-C 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection establishment method, and more particularly, to a connection establishment method for establishing a communication path when transferring an Internet protocol via an NBMA network.

[0002]

2. Description of the Related Art Conventionally, for example, ATM (Asynchronous Tra
nsfer Mode) network, X. 25 or NBMA (Non-Broadcast, Multi
-Access) network, when performing communication using the Internet Protocol (hereinafter referred to as IP), as an address resolution protocol for converting a network layer address into a data link layer address.
The official Internet-related standard RFC (Requ.) Issued by the Internet Engineering Task Force (ETF)
est For Comments) 2032 as NHRP (Next Hop
Resolution Protocol) has been standardized. FIG.
FIG. 9 is a configuration diagram of an ATM network 40 according to a conventional example,
On the ATM network 40, a logically independent IP
LIS-A 50, LIS-B 52, LI
Each SC 54 is defined, of which LIS-A
50 and LIS-C 54 have NHRP client NH
The CA 42 and the NHC-C 48 are directly connected, the sub-networks LIS-A 50 and the LIS-C 54 are connected via the LIS-B 52, and the NHS-A 44 of the NHRP server is connected to the LIS-A
A 50 and LIS-B 52, NHS-C 46 is LIS-B 52 and LIS-B
Each is directly connected to C54. And NHR
The P-client NHC-A 42 and NHC-C 48 and the NHRP server NHS-A 44 and NHS-C 46 are capable of selecting a partner each time communication with the ATM network 40 is started. SVC (Switched Virtual C
onnection) method. Here, an example in which an IP address is used as a network layer address and an ATM address is used as a data link layer address will be described.

[0005] In FIG. 5, for example, an NHRP client NHC-A 42 trying to communicate communicates an NHRP resolution request packet including a network layer address (IP address) C 2 of a destination client NHC-C 48 with an NHR.
It transmits to the P server NHS-A 44 (). When the NHS-A 44 receives the NHRP resolution request packet, the IP address C
2 determines whether or not the IP address belongs to the set of IP addresses described in the NHRP server table of the NHS-A 44, and if so, the NHS-A 44 converts the ATM address corresponding to the IP address into NHC. -A Send to 42. Then
The NHC-A 42 performs signaling with the other party using this ATM address, and a communication path is established. Also, as shown in the figure, the IRP is stored in the NHRP server table of the NHS-A 44.
If it is determined that the P address C2 does not exist and does not belong, the NHS-A 44 sends N to the NHS-C 46, another NHRP server that seems to be managing the destination IP address C2.
The HRP resolution request packet is transferred (). The NHS-C 46, which has received the NHRP resolution response packet, confirms that the destination IP address C2 is described in the NHRP server table, and changes the data link layer address (ATM address) Vc corresponding to the IP address C2 to NHS-A. The NHS-A 44 returns the ATM address Vc to the NHC-A (44).
Return to A 42 (). And of the NHRP client
The NHC-A 42 uses this ATM address Vc to signal between the destination client NHC-C 48 (), and thereby VP / V as a resource used for communication.
C (VirtualPass: virtual path identifier / Virtual Channe
l: virtual channel identifier) is determined, and a communication path can be established.

[0004]

However, in such a conventional connection establishment method, NHRP
Specifies the address resolution procedure when the ATM network 40 is set up by the SVC method of the partner selection connection type. In the case of the SVC method, each N
Since the HRP clients (NHC-A 42, NHC-C 48) require the above-mentioned signaling protocol, the apparatus scale becomes large and expensive, and the processing load on the client becomes large, so that the processing speed must be increased. There was a problem that the communication speed was slow. Also, multiple NHRPs
The sub-networks (LIS-A 50, LIS-C 54) to which the clients (NHC-A 42, NHC-C 48) are directly connected,
Permanent Virtual Connectio (PVC) that is used in offices and the like to fix and connect to the communication partner
n) When the ATM network 40 is configured by setting up by the method and setting up the sub-network LIS-B 52 interposed therebetween by the SVC method of the other party connection type, communication between both NHRP clients may not be possible. was there. Therefore, if a connection is established between clients through a router, communication becomes possible, but a new problem arises in that the communication speed is greatly delayed by passing through the router. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to set up a sub-network to which NHRP clients at both ends are connected by a PVC method, and to set a sub-network interposed therebetween in the SVC. Even if it is set up in the system, high-speed communication can be performed and N
It is an object of the present invention to provide a connection establishment method that eliminates the need to provide a signaling function on the HRP client side and can reduce the apparatus cost.

[0005]

According to the first aspect of the present invention, there is provided a sub-network in which a client performing communication using an Internet protocol via an NBMA network and an NHRP server having an NHRP address resolution function are fixedly connected. In a network in which a plurality of are connected, a communication establishment method using an address resolution request packet when performing communication between the clients, comprising: Transmitting an address resolution request packet to an NHRP server;
A step of checking whether the destination network layer address of the address resolution request packet received by the RP server belongs to a set of network layer addresses in the NHRP server table of the server, and a check in the previous step that the destination does not belong to the set NHR of other sub-networks
Transferring the address resolution request packet to a P server; and when the destination NHRP server connected to the subnetwork to which the destination client belongs receives the address resolution request packet, the server's own data link layer address and NHRP server Sending the destination client's data link layer address stored in a table to the sending NHRP server;
The HRP server signaling the NHRP server on the destination side. The communication between the clients is enabled by establishing a communication path between the servers by the signaling.

According to this, the address resolution request packet is transmitted to the transmission side NHRP server of the subnetwork to which the transmission side client belongs, and the destination network layer address of the address resolution request packet received by the transmission side NHRP server is changed to the address of the server. Check whether it belongs to the set of network layer addresses in the NHRP server table, and if it is determined that it does not belong to the set, transfer the address resolution request packet to the NHRP server of another subnetwork, and When the destination NHRP server connected to the belonging subnetwork receives the address resolution request packet, the destination NHRP server transmits the data link layer address of the server itself and the data link layer address of the destination client stored in the NHRP server table. Sent to server, the sender NHRP server communication path performing signaling between the destination side NHRP server is established. For this reason, the transmitting client does not need to perform the signaling processing by itself and does not need to have a signaling function on the client side, so that the apparatus cost can be reduced. In addition, the transmitting client only needs to transmit an NHRP resolution request packet to a server having an address resolution function when establishing a communication channel, and establishes a communication channel by processing the address resolution request on the server side. So you can
Even if networks of different systems are interposed between clients, a communication path can be established and high-speed communication can be performed.

According to a second aspect of the present invention, in the connection establishment method of the first aspect, each of the sub-networks is constructed by a PVC system, and these sub-networks are mutually connected via a network constructed by an SVC system. Connected. According to this, the network interposed between the communicating clients is the PV
Even when the C method and the SVC method are mixedly constructed, a communication path can be established, and high-speed communication can be performed.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of an ATM network 10 according to the present embodiment. In FIG. 1, logically independent IP sub-networks LIS-A 20, LIS-B 22, LIS-
C24 is defined and NHC-A 12 is an NHRP client directly connected to the ATM network and
The NHC-C 18 is set up by a fixed connection type PVC system. And NHC- of NHRP client
It is assumed that resource Va is assigned to A12 and resource Vc is assigned to NHC-C 18 of the NHRP client. Also, NHS-A which is an NHRP server
14 is a sub-network of LIS-A 20 and LIS-B 2
2 and A for each interface
IP addresses 2 and B1 are assigned, and Na is held as an ATM address. Similarly, the NHRP-server 16 of the NHRP server belongs to the sub-networks LIS-B 22 and LIS-C 24,
IP addresses B2 and C1 are assigned to each interface.
Nb is held as an address. Also, the NHC-A 12 of the NHRP client is the LIS-A of the sub-network.
20 and has been assigned an IP address A1, and the NHRP client NHC-C 18
It belongs to the subnetwork LIS-C 24 and is assigned an IP address C2. Here, it is assumed that the NHS-A 14 of the NHRP server manages the LIS-A 20 of the subnetwork, and the NHS-C 16 of the NHRP server manages the LIS-C 24 of the subnetwork. That is, the NHS-A 14 has an IP address A * (* is an arbitrary value)
When receiving the NHRP resolution request packet for
There is an obligation to respond to the NHRP Resolution Response Packet.

FIG. 2 is a diagram for explaining the configuration of an ATM cell 30 used in the ATM network 10 of FIG.
The header 26 of the ATM cell 30 includes a VPI (virtual path identifier), a VCI (virtual channel identifier), and the like, and a shortcut VCC (VirtualCha) that can directly communicate with the other party in the ATM network 10 using these.
nnel Connection: virtual channel connection) and provide high-speed internetworking functions. The payload 28 following the header 26 includes user information and the like. FIG. 3 shows the NH in FIG.
FIG. 3 is a diagram showing functional blocks in the NHS-A 14 or NHS-C 16 of the RP server. In FIG. 3, the NHRP server 1
4 (16) is an NHRP for processing an NHRP packet.
The server processing unit 140 (160) determines the next hop when transferring the NHRP packet (Next hop (Next
Hop) search unit 142 (162), routing table 1 referenced by next hop search unit 142 (162)
44 (164), NHRP server processing unit 140 (16
0) refers to the NHRP server table 148 (16
8) and a signaling processing unit 146 (166) for signaling the NHRP processing which is a feature of the present invention. Then, as a result of performing the signaling, the LIS-A 20 and the LI
By switching an ATM switch (not shown) included in the SC 24, a communication path (connection) can be established. In order to construct the routing table 144 (164), RIP (Routin
g Information Protocol: Distance Vector Routing Protocol and OSPF (Open Shortest Path First:
An existing routing protocol such as a link state type routing protocol) or a static setting by a network administrator is used to accurately reflect the ATM network configuration of FIG. Also, N
The HRP server processing unit 140 (160) and the signaling processing unit 146 (166) have a network interface, and these are each connected to the above-described ATM switch.

Next, the operation will be described. FIG. 4 is a flowchart illustrating the operation of the present embodiment. In FIG. 4, from the NHC-A 12 which is the NHRP client of FIG.
In the case where an IP packet is transmitted to the NHC-C 16, a procedure for performing address resolution and establishing a connection is shown. First, the NHC-A 12 of the NHRP client uses the NH
An RP resolution request packet is transmitted to the NHS-A 14 of the NHRP server (FIG. 1: step S1). NHRP server processing unit 140 in NHS-A 14 of the NHRP server
Refers to the NHRP server table 148 and refers to the destination I
It is determined that the P address C2 is not under its own control (step S2). Then, the next hop search unit 142 searches the routing table 144 to determine that the NHS-C 16 of the NHRP server is optimal as the next hop destination (step S3), and transfers the NHRP resolution request packet to the NHS-C 16. (Step S in FIG. 1)
4). NHS-C 16 that received the NHRP resolution request packet
The NHRP server processing unit 160 of FIG. 4 refers to the NHRP server table 168, recognizes that the destination IP address C2 is under its own control (step S5), and allocates the resource Vc assigned to the NHC-C 18 from the NHRP server table 168. Is obtained (step S6). Next, NHS-C 16 N
HRP server processing section 160 has its own ATM address N
b, and creates an NHRP resolution response packet based on the resource Vc allocated to the NHC-C 18 and the NHS-A 14
(Step S7 in FIG. 1). In the NHRP server processing unit 140 of the NHS-A 14 of the NHRP server,
It extracts its own ATM address Nb and resource Vc from the received NHRP resolution response packet and passes them to the signaling processing unit (step S8).

[0011] The signaling processing unit 146 of the NHRP server NHS-A 14 issues a signaling call to the ATM address Nb of the NHS-C 16 using the resource Vc (FIG. 1).
Middle: Step S9). With successful signaling,
The resource Vc becomes valid in the LIS-B 22 (step S10). In the signaling process of the NHRP server NHS-A 14, an NHRP resolution response packet is created by the resource Vc and responded to the NHC-A 12 (Step S11 in FIG. 1). As a result, the sub-network LIS-A
Also at 20, the resource Vc is valid. The NHRP client NHC-A 12 extracts the resource Vc from the received NHRP resolution response packet, and converts the IP packet using the resource Vc into the NHRP client NHC-C 18.
(Step S12 in FIG. 1).

As described above, according to the present embodiment, a sub-network to which both NHRP clients performing communication are connected is set up by the PVC method,
Even when the sub-network interposed therebetween is set up by the SVC method, high-speed communication can be performed, and there is no need to provide a signaling function on the NHRP client side, thereby reducing device cost. be able to. In this embodiment, the IP address is used as the network layer and the ATM address is used as the data link layer. However, other network layer protocols may be used, or NBMA other than ATM may be used.
The present invention can be implemented using a network, and similarly, a favorable effect can be obtained.

[0013]

As described above, according to the first aspect of the present invention, the transmitting client does not need to perform a signaling process by itself and does not need to have a signaling function on the client side. Equipment costs can be reduced. In addition, the transmitting client only needs to transmit an NHRP resolution request packet to a server having an address resolution function when establishing a communication channel, and establishes a communication channel by processing the address resolution request on the server side. Therefore, even if networks of different systems are interposed between clients, it is possible to establish a communication path and perform high-speed communication. According to the second aspect of the present invention, it is possible to establish a communication path even in a case where a network interposed between clients performing communication is constructed by mixing a PVC system and an SVC system. It is possible, and high-speed communication can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ATM network according to the present embodiment.

FIG. 2 shows an ATM used in the ATM network of FIG. 1;
FIG. 3 is a diagram illustrating a configuration of a cell.

FIG. 3 shows the NHS-A or NHS- of the NHRP server in FIG.
FIG. 4 is a diagram showing functional blocks in C.

FIG. 4 is a flowchart illustrating the operation of the present embodiment.

FIG. 5 is a configuration diagram of an ATM network according to a conventional example.

[Explanation of symbols]

 10 ATM network, 12 NHC-A, 14 NHS-A, 16 NHS-C, 18 NHC-C, 20 LIS-A, 22 LIS-B, 24 LIS-C, 26 header, 28 payload, 30 ATM cell, 140 , 160 NHRP server processing unit, 142,162 next hop search unit, 144,164 routing table, 146,166 signaling processing unit, 148,168 NHRP server table.

Claims (2)

[Claims] 1. A method for communicating with a client that communicates using an Internet protocol over an NBMA network.
In a network in which a plurality of sub-networks fixedly connected to an NHRP server having an HRP address resolution function are connected, a connection for establishing a communication path using an address resolution request packet when communicating between the clients is established. Transmitting an address resolution request packet from a transmitting client to a transmitting NHRP server of a subnetwork to which the transmitting client belongs; and determining a destination network layer address of the address resolution request packet received by the transmitting NHRP server as the destination. A step of checking whether or not the server belongs to a set of network layer addresses in an NHRP server table of the server; and, if it is determined in the previous step that the server does not belong to the set, the address resolution request to an NHRP server of another sub-network. Forwarding the packet and When the destination NHRP server connected to the subnetwork to which the destination client belongs receives the address resolution request packet, the data link layer address of the server itself and the data link layer address of the destination client stored in the NHRP server table are used. To the transmitting NHRP server; and the transmitting NHRP server performs signaling with the destination NHRP server. The communication between the clients is established by establishing a communication path between the servers by the signaling. A connection establishment method for enabling communication. 2. The method according to claim 1, wherein each of said sub-networks is a PVC.
Are constructed in such a way that these sub-networks
2. The connection establishment method according to claim 1, wherein the connection is established via a network constructed by a VC system.