JP2638429B2 - Packet relay method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is used for interconnecting local area networks (hereinafter "LAN"). In particular, it relates to an inter-LAN connection for connecting LANs at a network layer. More specifically, the present invention relates to a packet relay system using a network layer address.

Japanese Patent Laid-Open No. Sho 62-62
91038, JP-A-1-18333, 1-23
Nos. 646, 2-104043, and 3-123137.

[0003]

2. Description of the Related Art In order to connect LANs at a network layer, a packet relay using an inter-LAN connecting device (also referred to as a "router" or a "relay node") has conventionally been performed. The LAN-to-LAN connecting apparatus searches a routing table for a network layer destination address for each packet during packet transfer, extracts information on a node to be transmitted next, and relays the packet.

[0004]

In the conventional method, however, this is not a problem when the hierarchical structure of the address is simple and the address length is short. However, a longer address length is required to enable connection of more nodes. When using, TCP
If the lengths of the network portion and the host portion of the address differ from network to network (address class, subnet) as in / IP, processing such as an address mask is required, so that routing table search processing becomes complicated, and There is a problem that the load of the routing process in the relay node increases.

[0005] None of the above publications discloses a technique for solving such a problem.

[0006] It is an object of the present invention to solve such a problem and to provide a packet transfer system capable of reducing a packet transfer load on a packet relay node.

[0007]

SUMMARY OF THE INVENTION A packet relay system according to the present invention includes a relay node for connecting different logical networks to each other, and the relay node is assigned a network layer address. A routing table in which information on the next-stage relay node existing on the same logical network as the own relay node serving as the next relay point for sending a packet to the destination is recorded. The relay node assigns an identification number having a shorter number of bits to a network layer destination address to be referred to for relaying, and notifies the transmission source node of it. To the same destination packet instead of the network layer destination address. Identification number Te by characterized in that it comprises a means for retrieving the transmission destination.

More specifically, the relay node assigns an identification number having a shorter bit length than the network layer address to the network layer destination address of a packet received by the relay node and being unique in the own node, and assigns the identification number to the relay node. Means for notifying the preceding relay node existing on the same logical network as the own node and directly transmitting the packet, and means for releasing the already assigned identification number and notifying the preceding relay node And when a notification of the assignment of an identification number to the network layer destination address of the packet sent by itself is received from the next-stage relay node, an identification number is added instead of the network layer destination address, and the next-stage relay node Means for transmitting to an ID number corresponding to the ID number assigned by the own node Means for storing information including the network layer destination address, that is, a routing table based on the identification number; means for deleting the corresponding information of the storage means when the assignment of the identification number is released; Means for transferring the packet based on the information stored in the storing means.

[0009]

The relay node assigns an identification number having a shorter bit length to the network layer destination address to be referred for relaying, notifies the other node of the identification number, and substitutes the packet of the same destination for the network layer destination address instead of the network layer destination address. Add it. As a result, the routing table based on the identification number is held, and the routing table is searched based on the identification number.

[0010]

FIG. 1 is a diagram showing a network configuration according to an embodiment of the present invention. The logical networks NW1, NW2 are connected via the relay node R1, and the logical networks NW2, NW2,
NW3 is connected via relay node R2. A network layer address is assigned to each of the relay nodes R1 and R2. Each of the relay nodes R1 and R2 has a next stage existing on the same logical network as its own node as a next relay point for sending a packet to the destination with respect to the network layer destination address. And a means for referring to the routing table to determine a destination of a packet. The relay nodes R1 and R2 further assign to the network layer destination address of a packet received by the relay node R1 and R2 an identification number having a shorter bit length than the network layer address and being unique to the own node. Means for notifying the preceding relay node which is the direct transmission source of the packet existing on the same logical network, means for releasing the already assigned identification number and notifying the preceding relay node, Has been notified of the assignment of the identification number to the network layer destination address of the packet sent from the next-stage relay node, the identification number is added instead of the network layer destination address, and the packet is transmitted to the next-stage relay node. Means and the network corresponding to the identification number assigned by the own node. A routing table by an identification number as a means for storing information including a destination address, a means for deleting the corresponding information in the routing table by the identification number when the assignment of the identification number is released, and an identification number. Means for transferring the transmitted packet based on the information stored in the routing table by the identification number.

FIG. 2 shows that the node N1 on the logical network NW1 successively sends four packets to the node N2 on the logical network NW3,
1, relay nodes R1, R when transferred via R2
6 is a sequence chart showing transmission and reception of a packet between the two.

[0012] In the relay nodes R1, so not receiving the assignment of the identification number for the node N2 of the destination, the one th packet Ri feed by adding a network layer destination address to the relay node R2, the two eyes of the packet After the transmission with the network layer destination address added, it receives the assignment notification from the relay node R2, and sends the third and fourth packets to the relay node R2 with an identification number added. At the relay node R2, the identification number has a shorter bit length than the network address, and the routing table based on the identification number has fewer entries than the routing table based on the network layer address.
The third and fourth packets can be routed faster than the second packet.

FIG. 3 is a block diagram showing a configuration example of the relay node. This relay node is a packet input / output unit 1
1, MAC layer processing unit 12, routing processing unit 1
3. It includes an identification number assignment / release processing unit 14 and a routing table 15. The packet input / output unit 11 performs conversion between a physical signal and a bit string. The MAC layer processing unit 12
The AC layer header is processed. The routing processing unit 13 determines a next node from the network layer destination address / identification number. The identification number assignment / release processing unit 14 and the routing table 15 manage the identification number of the own node. The routing table 15 includes a routing table based on a network layer address and a routing table based on an identification number.

FIG. 4 is a flowchart showing the operation of the relay node.

When a packet is input (A1), the MAC
The process for the layer header is performed (A2), and if the notification is the assignment / release of the identification number, the routing table is updated (A3, B1). If not, it checks the identification number assignment flag of the network layer, and if it is on, extracts the identification number and searches the routing table by the identification number (A5). If it is off, the network layer destination address is extracted and a routing table based on the network layer address is searched (C
Along with 1), it is determined whether an identification number should be assigned to the network layer address (C2). In the case of the assignment, an assignment notification is sent to the preceding node, an entry is created based on the search result of C1, and processing such as addition to the routing table by the identification number is performed (C3). C2
Is determined based on statistics so that an identification number is assigned to an address having a large number of packet inputs.

By searching the routing tables of the processes A5 and C1, it is known whether or not an identification number has been assigned to the destination address at the next-stage node. If not assigned, a network layer destination address is added (A6, A7, D1), and packet output processing is performed (A8, A9).

FIG. 5 shows a frame format of a packet when an identification number is not assigned and a frame format when an identification number is assigned. Also,
6 and 7 show a format example of a routing table based on a network layer address and a format example of a routing table based on an identification number.

For the method of constructing the routing table based on the network layer address, dynamic routing, static routing and other methods can be used. Processing of the MAC layer at the time of reception and transmission, that is, processing of determining whether or not the MAC address should be received at the time of reception, and at the time of transmission, knowing the MAC address of the next node from the network layer address or identification number of the next node and adding it to the packet The description of the processing such as is omitted.

[0019]

As described above, in the packet relay system of the present invention, in each relay node connecting different logical networks to each other, an identification number is assigned to a network layer address, and a packet to which an identification number is added is assigned. Is obtained by searching the routing table based on the identification number for the information of the next stage node. In the routing table based on the identification number, the bit length for determining the match is short and the number of entries is small, so that the packet relay processing is reduced.

[Brief description of the drawings]

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

FIG. 2 is a sequence chart showing an example of transfer of a packet between relay nodes.

FIG. 3 is a block diagram showing a configuration example of a relay node.

FIG. 4 is a flowchart showing the operation of the relay node.

FIG. 5 is a diagram showing a frame format of a packet when an identification number is not assigned and a frame format when an identification number is assigned;

FIG. 6 is a diagram showing a format example of a routing table based on network layer addresses.

FIG. 7 is a diagram showing a format example of a routing table based on an identification number.

[Explanation of symbols]

 N1, N2 node NW1, NW2 logical network R1, R2 relay node 11 packet input / output unit 12 MAC layer processing unit 13 routing processing unit 14 identification number assignment / release processing unit 15 routing table

Claims (2)

(57) [Claims] 1. A relay node for connecting different logical networks to each other, the relay node being assigned a network layer address, the relay node having a network layer destination address for sending a packet to its destination. Packet relay including a routing table in which information on the next-stage relay node existing on the same logical network as the own node serving as a relay point of the packet is recorded, and means for determining a packet transmission destination by referring to the routing table In the method, the relay node receives a network layer destination address of a packet received by the relay node.
The bit length is shorter than the network layer address
Means to assign unique identification number in own node
And this identification number on the same logical network as the own node.
Previous relays that are the immediate source of the packet that is present
Means for notifying the node and canceling the assignment of the identification number already assigned
Means for notifying the relay node of the second stage, and checking the network layer destination address of the packet sent by itself.
From the relay node at the next stage
The network layer destination address
Instead, add an identification number and send it to the next relay node.
Means and the identification number assigned to the own node
Stores information including the corresponding network layer destination address
Means for storing the identification number when the assignment of the identification number is released.
Means for deleting the corresponding information of the column, and for the packet sent with the identification number added,
A packet based on the information stored in the storage means;
And a means for performing transfer . The means for assigning an identification number is a network.
Network layer destination address and network layer source address
Including means for assigning identification numbers to combinations of
The packet relay system according to claim 1.