JPH06318953A - Data alternate system by pushing-back to originating node - Google Patents

Abstract

PURPOSE:To prevent a packet from being abandoned after a ping-pong phenomenon between each node and a node in the preceding stage because of the absence of outgoing paths in each node with respect to the routing processing of a data communication system. CONSTITUTION:Each node 10 is provided with a terminating node path selection processing part 1, an originating node path selection processing part 2, and an adjacent node alternate impossibility report processing part 3. When the terminating node path selection processing part 1 detects that any outgoing paths cannot be selected, the adjacent node detour impossibility report processing part 3 informs adjacent nodes that detour is impossible, and simultaneously, the originating node path selection processing part 2 selects an outgoing path to the originating node, and data is transmitted to the selected outgoing path to the originating node to secure the alternate route.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data circumvention method by pushing back a source node, and in particular, in a routing process of a data communication system, a data circumvention when all routes from a relay node to a destination node become an obstacle. Regarding the scheme.

[0002]

2. Description of the Related Art Conventionally, in a packet network which employs a datagram method for performing routing in units of packets as a data transfer method between nodes constituting a network, communication between terminals is performed by the terminals. The relay node between the source node and the destination node, which is controlled between the nodes directly connected to the destination node, performs routing by using the information added to the packet to be transferred and the routing information of the relay node, and the destination route for the destination node. The packet is transferred to the destination node. In such a packet network, if a relay node or relay route fails and there is no output route for the destination node at the relay node, a relay packet is sent to the input route and pushed back to the preceding node, and at the same time the destination node is sent. Notify that the destination route cannot be selected (detour not possible) to the preceding node, and the preceding node performs rerouting processing so as not to select the route that passes through the node that received the notice that the detour cannot be made. A detour for the station node was secured. However, if the detour route for the destination station cannot be secured even at the preceding node, the packet will come and go between the relay nodes, resulting in a ping-pong phenomenon, and the packet will be discarded when the number of relay stages exceeds and the communication between terminals will be interrupted. was there.

This conventional problem will be described with reference to FIGS. FIG. 5 shows a packet route when the route is normal, FIG. 6 shows a packet route when the route ab fails, and FIG. 7 shows a packet route when the route be also fails.
FIG. 8 shows routing data in each node. In FIG. 5, each node constituting the network selects an outgoing route by a fixed detour method, and the routing data of each of the nodes A to F is defined in advance as shown in FIG. Then, the terminal D under the control of the node A
The terminal DTE-f under the TE-a and the node F is connected to the node A.
→ B → C → F / F → C → B → A route (each node first
It is assumed that they are communicating using a route.

At this time, as shown in FIG. 6, when a failure occurs in the relay route ab between the node A and the node B, the DTE-
The packet a → DTE-f is transferred by selecting the first route of FIG. 8 at each node, or by selecting the detour when the first route cannot be used, so that the packet is transferred from node A to node F. Select the detour ab of (see FIG. 8) and select node A →
Transferred via D → E → F, and conversely DTE-f → DTE
The packet of -a is transferred by selecting the detour route when the first route for node A in FIG. 8 or the first route in FIG.
A route is selected, and a detour be for the node A station is selected at the node B.
Is selected, the data is transferred via the nodes F → C → B → E → D → A.

Further, in this state, as shown in FIG. 7, when a failure occurs in the relay route be between the nodes B and E, DT
The packet of E-a → DTE-f is node A → D → E →
The packet of DTE-f → DTE-a is transferred via F, but the packet of DTE-f → DTE-a is transmitted from node B to node A in the first route a.
Since both b and the detour be are faulty, the packet cannot be transmitted to the destination node A, and the packet is pushed back to the route bc which is the route of the packet entering the node B. At the same time, the node B informs the node C that there is no outgoing route for the node A to the node C by the network control packet (not-to-be-routed notification packet).
To notify. As can be seen from FIG. 8, node C does not have a detour for node A, so node C
Similarly to node B, since there is no outgoing route for node A, the packet is forwarded to the relay route bc which is the incoming route of the packet.
To the node B and the node C, and the packet is discarded when the number of relay stages exceeds. In order to solve this, it is necessary to newly add a relay route in the node C to secure a detour for the node A and reduce the probability that the detour is impossible.

[0006]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, 10 is one node in the routing processing of the data communication system. The node 10 has a destination node route selection processing unit 1, a source node route selection processing unit 2, and an adjacent node detour impossible notification processing unit 3, and the destination node route selection processing unit 1 cannot select an outgoing route. When this is detected, the adjacent node detour impossible notification processing unit 3
Notifies the adjacent node that no detour is possible, and at the same time, the originating node route selection processing unit 2 selects an outgoing route for the originating node and transmits data to secure the detour.

[0007]

[Function] When each node detects that the outgoing route cannot be selected, it notifies the adjacent node that no detour is possible, and at the same time, selects the outgoing route for the originating node to transmit data to the destination node. Since we will secure a detour for
The ping-pong phenomenon does not occur even if there is a failure in the relay path.

[0008]

[Embodiment] According to the present invention, when an outgoing route for a destination node cannot be selected (a detour is not possible) when determining an outgoing route for a relay packet, the outgoing route is re-routed with the source node number given to the relay packet. It is characterized by performing a route and selecting an outgoing route. FIG. 2 is a block diagram showing the configuration of the node according to the embodiment of the present invention. In this figure, this node represents the relay processing unit of the packet switch. 3 shows a format of a relay packet transferred in the network according to the embodiment of the present invention.

In FIG. 2, the relay packet processing unit 21
Is a routing table group (rt) 22, a packet reception unit (PR) 23, and a routing reception analysis unit (R).
A) 24, a route selection processing unit (HDS) 25, a source node route selection processing unit (HDD) 26, a detour notification processing unit (CGT) 27, and a packet transmission unit (PS) 28. There is. Introduced by the present invention are a source node route selection processing unit (HDD) 26 and a detour notification processing unit (CGT) 27, which are hatched in the figure.

The packet received from the relay line has the format shown in FIG. 3, and in the relay packet control information section therein, the SPC indicating the inter-node packet type,
P indicating the priority, TG indicating the routing class, HOP indicating the number of relay stages, DNOD indicating the destination node number, SNOD indicating the source node number, and DLN indicating the destination terminal identification information.
K, and SLNK indicating the calling terminal identification information are included.

The packet received from the relay line is transferred from the packet reception unit (PR) 23 to the routing reception analysis unit (R).
A) Passed to 24. Routing reception analysis unit (RA)
In 24, the destination node number DNOD in the control information of the received packet shown in FIG. 3 is analyzed, and if it is determined to be a relay packet, the route selection processing unit (HDS) 25 is activated. The route selection processing unit (HDS) 25 uses the DN of the received packet.
Referring to the routing table group (rt) 22 in the OD, the routing table rt (dnod) for the destination node
To find the first priority route hl in rt (dnod). The route selection processing unit (HDS) 25 uses the route hl
Is inquired to the route state management unit HM (not shown), and if normal (transmission is possible), the packet transmission unit (PS)
28 is requested to transmit the packet to the route hl. If it is abnormal (transmission is impossible), the route h2 of the next rank is taken out and the same processing is performed. In this way, when the route is selected and the route for the destination node cannot be selected, the route selection processing unit (H
The DS) 25 activates the detour notification processing unit (CGT) 27 and the originating node route selection processing unit (HDD) 26. The detour notification processing unit (CGT) 27 requests the packet transmission unit (PS) 28 to transmit a detour impossible notification packet in order to notify the adjacent node that the destination route for the destination node cannot be selected. The source node route selection processing unit (HDD) 26 extracts the source node number SNOD in the control information from the packet, and the routing table group (rt) 2 is obtained with this SNOD.
2, the routing table rt for the source node
(Snod) is searched for, the first priority route hl in it is extracted, and the same process as the route selection processing unit (HDS) 25 is performed, and the packet is transmitted to the route for the source node. In the selection of the outgoing route for the normal source node, the route in which the packet is received is included, so that no detour is possible.

FIG. 4 is a diagram showing a packet route according to an embodiment of the present invention. In this figure, each node uses the routing data shown in FIG. In FIG. 4, a node A subordinate terminal DTE-a and a node D subordinate terminal DTE-f represent nodes A → B → C → F / F → C → B → A.
It is assumed that communication is performed using the route (1st route of each node).

In this state, the relay route a between the nodes A and B
When the failure of b occurs, the packet of DTE-a → DTE-f is transferred via node A → D → E → F because the detour for the node F station in node A is ad as shown in FIG. The packet of DTE-f → DTE-a is
In the node B, the detour route be for the node A station is selected (see FIG. 8), and the data is transferred via the nodes F → C → B → E → D → A.

Further, in this state, if a failure occurs in the relay route be between the nodes B and E, DTE-a → DTE-f
Packet is transferred through nodes A → D → E → F, but the packet of DTE-f → DTE-a is a failure in node B because both the first route ab and the detour route be.
The packet cannot be transmitted to the destination node A, and the adjacent node C is notified that there is no outgoing route for the node A by the network control packet (rerouting impossible notification packet), and the packet for the source node (node F) Relay route b
Select c and send the packet to node C. Since the node C receives the detour impossible notification packet for the node A from the node B, it cannot select the first route bc for the node A and has no detour for the node A. Similarly to the node B, the node C also performs the outgoing route selection process for the source node (node F) to select the relay route cf, and transmits the packet to the node F. Since the node F receives the node A detour prohibition notification packet from the node C, it cannot select the first route cf for the A node, and selects the detour route ef (see FIG. 8). A packet is sent to the node E. After that, the packet is transferred from node E → D → A.

[0015]

As is apparent from the above description, according to the present invention, a detour can be secured in a node in which a route for a destination node cannot be selected for a network fault such as a node fault / route fault. Therefore, it has an effect of guaranteeing end-to-end terminal communication at the time of network failure and largely contributes to improvement of network reliability.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a block diagram showing a configuration of a node according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a format of a relay packet transferred in the network according to the embodiment of the present invention.

FIG. 4 illustrates a packet route according to an exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a conventional packet route in a normal state.

FIG. 6 is a diagram showing a conventional packet route when a failure occurs in a route ab.

FIG. 7 is a diagram showing a conventional packet route when a failure occurs in a route ab or be;

FIG. 8 is a diagram showing routing data in each node.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Destination node route selection processing unit 2 ... Originating node route selection processing unit 3 ... Adjacent node detour impossible notification processing unit 10 ... Node

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Tachida 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Kansai Communication Systems Co., Ltd.

Claims (1)

[Claims] 1. In a routing process of a data communication system, each node (10) has a destination node route selection processing unit (1), a source node route selection processing unit (2), and an adjacent node detour impossible notification. When the destination node route selection processing unit (1) has a processing unit (3) and detects that the destination route cannot be selected, the adjacent node detour unavailable notification processing unit (3) Detour notifying is performed, and at the same time, the originating node route selection processing unit (2) selects an outgoing route for the outgoing node, and transmits data to the selected outgoing route for the outgoing node to secure a bypass route. Data bypass method by pushing back the originating node.