JP2000124949A - Packet switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliability packet switch in simple configuration and to provide a packet switch capable of attaining expansion in scale. SOLUTION: A sequence number is applied for each destination port of a packet by an input port 1. Afterwards, this packet is inputted to a switch network and switched to a prescribed output port 3. At the output port 3, the received packets are rearranged for each sequence number. Plural switch networks 21 are parallelly arranged and the packet of a system first arriving at the output port from each system is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a packet switch having a plurality of routes between input / output ports. Packets can be either variable length or fixed length.

[0002]

2. Description of the Related Art In order to increase the capacity of a packet switch,
The unit switches are interconnected in multiple stages to form a switch network. FIG. 8 is a diagram showing a switch network interconnected in multiple stages. When a switch network as shown in FIG. 8 is configured, by distributing a plurality of routes between input and output of the switch network, load distribution can be performed in the switch network. In such a configuration, it is necessary to evenly distribute packets input from one input port to a plurality of routes.

At this time, in the switch network shown in FIG. 8, since the packet transfer time differs for each route, the order of the packets is reversed, and it is necessary to compensate the order of the packets at the output port. As the conventional order compensation of packets, a time stamp is added to a packet at an input port, and the packets are rearranged according to the time stamp at an output port. At this time, the arrival of the packet is waited until the maximum allowable delay time, and the rearrangement is performed thereafter.

FIG. 9 is a diagram showing a packet switch in which a plurality of switch networks are arranged in parallel. As shown in FIG. 9, a plurality of switch networks shown in FIG. 8 are arranged in parallel to increase reliability. In such a configuration, when a failure is detected in the active switch network, switching to the standby switch network is performed.

[0005]

In the above prior art, as shown in FIGS. 8 and 9, the number of unit switches increases as the switch scale increases, thereby reducing the reliability of the switch network. . If even one of the unit switches constituting the switch network fails, communication passing through the unit switch will not be normal, and it is necessary to switch the entire switch network to the standby system.

At this time, if one or more unit switches fail simultaneously in each of the working system and the standby system as shown by the shaded portion in FIG. 9, it becomes impossible to maintain all communication at the same time. In this way, the switch scale becomes large,
The reliability decreases as the number of unit switches increases. Further, when a failure occurs in a unit switch in a switch network, a mechanism for detecting and notifying the failure is required, and the switch network configuration becomes complicated.

The present invention has been made in view of such a background, and an object of the present invention is to provide a highly reliable packet switch with a simple configuration. An object of the present invention is to provide a packet switch that can be scaled up.

[0008]

According to the present invention, a sequence number is assigned to each destination port of a packet at an input port. Thereafter, this packet is input to the switch network and is switched to a predetermined output port. At the output port, the received packets are rearranged for each sequence number. Since packets arrive from a plurality of input ports, rearrangement is performed for each input port. This makes it possible to compensate for the order of packets switched between the input / output ports.

The present invention has a configuration in which the reliability is improved by arranging a plurality of switch networks in parallel. At this time, one packet is copied for each switch network arranged in parallel and each switch is copied. Distributed to the network. Therefore, a plurality of packets with the same sequence number arrive at one output port, but rearrangement is performed using a sequence number for each input port, so that the packets are exactly the same packet copied, or ,
It is easy to distinguish between different packets transmitted from different input ports. Therefore, a packet that can be discarded can be determined without performing complicated processing such as comparing the contents of the packet.

In this way, by selecting the packet of the system that first arrives at the output port from each system of the plurality of switch networks arranged in parallel, it is simpler than in the case of performing active / standby switching when a failure occurs With such a configuration, reliability can be improved. With such a configuration, packet transfer can be continued as long as unit switches at the same position in each system do not fail.

Further, according to the present invention, a test packet specifying a route is transmitted from an input port to a certain output port, and the test packets from each system are inspected at the output port, whereby the routes of all the systems are checked. Inspection can be performed.

That is, the present invention relates to a packet switch, comprising an input port from which a packet arrives, a switch network for switching the packet according to its destination information, and an output port for outputting a packet switched by the switch network. It is a packet switch provided.

Here, it is a feature of the present invention that the input port includes means for assigning an identification code of the input port and a series of sequence numbers to the packet in accordance with the arrival order of the packet, and the output port is provided with: Means for adjusting the order of packets for each input port according to the identification code and the sequence number.

A plurality of the switch networks are arranged in parallel, and means are provided for copying packets by the number of the switch networks, and means for distributing the copied packets to the plurality of switch networks arranged in parallel, respectively. Preferably, the means for adjusting the order includes means for discarding packets arriving after the second when a plurality of packets having the same sequence number and the identification code of the input port arrive.

[0015] The apparatus may further comprise means for transmitting a test packet specifying a switching path from the input port to the output port, and means for receiving the test packet and determining whether there is a failure in the switching path. it can.

[0016]

Embodiments of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a main part of a packet switch according to the present invention. For simplicity of description, FIG. 1 shows one input port 1 and one output port 3, but actually, a plurality of input ports and output ports are provided.

[0017] The present invention is a packet switch, an input port 1 packet arrives, the switch network 2 ₁ and 2 ₂ for switching packets according to the destination information, the switch network 2 ₁ and 2 ₂ are switched And an output port 3 for outputting the output packet.

Here, the feature of the present invention is that the input port 1 assigns an identification code of the input port 1 and a series of sequence numbers to the packet in accordance with the arrival order of the packet, and the output port 3 The order of the packets is adjusted for each input port according to the identification code and the sequence number.

The switching network 2 ₁ and 2 ₂ are arranged in parallel, the input port 1, the packet number of a copy of the switching network 2 ₁ and 2 _2, switch network 2 ₁ The duplicated packets and 2 ₂ The output port 3 discards the second and subsequent packets when a plurality of packets having the same sequence number and the input port identification code arrive.

The input port 1 transmits a test packet specifying a switching path from the input port 1 to the output port 3, and the output port 3 receives the test packet and determines whether there is a failure in the switching path.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing a status of assigning a sequence number at an input port. FIG. 3 is a diagram showing a packet rearrangement state at an output port. FIG. 4 is a diagram showing pointers used for rearranging packets. FIG. 5 is a diagram showing a block service order management table. FIG. 6 is a diagram showing a system selection status for each packet. FIG. 7 is a diagram showing a distributed fault monitoring situation.

As shown in FIG. 1, the packet switch input ports 1, switch network 2 ₁ and 2 _2, output port 3
Consists of Switching network 2 ₁ and 2 ₂ are duplicated. Input port 1 transmits the packet to the switch network 2 ₁ and 2 ₂ of both systems. At this time, a sequence number managed for each output port 3 as a destination is assigned to the packet. In the example shown in FIG. 2, FIG. 2 shows that the sequence numbers of the next packets destined for output ports a and b are 100 and 1 respectively.
Indicates a situation that is zero.

The switching network 2 ₁ and 2 ₂ disperses the packet output port 3 destined in multiple routes. Packets arriving from different routes are reordered at output port 3. In the example of FIG. 3, the output port number of the destination and the input port number of the transmission source are added to the packet header. The sequence number is given to the packet. In FIG. 3, the expected value of the sequence number of the next packet coming from the input port x is 96. Here, sequence number 9
Assume that up to 5 has already been served. Packets with sequence numbers 97, 98 and 100 have already arrived.
For the packet coming from input port y, the next expected value is 6, and 7 and 9 have already arrived.

As can be seen from FIG. 3, the order of packets arriving from each input port can be out of order. When the next packet with the expected value comes, it is necessary to transfer a group of continuous packets to the buffer, starting with that packet. In FIG.
Here is the principle to do it easily. FIG. 4 shows an example in which a packet having a sequence number 99 arrives and two blocks are connected to one block.

[0025] Among the packets that have already arrived, those with consecutive sequence numbers are referred to as blocks. The sequence numbers of the leftmost and rightmost packets of the block are written in the packets at both ends of the block (these numbers are referred to as a left pointer and a right pointer, respectively). The blocks can be easily connected because the leftmost and rightmost packets have the leftmost and rightmost pointers, respectively. When a block consisting of packets of sequence numbers 97 and 98 is connected to a block consisting of only packets of sequence number 100, the left pointer of the newly created block is 100 and the right pointer is 97.

The right pointer of the block connected to the right side is written as the right pointer of the packet of sequence number 100. The left pointer of the packet of sequence number 97 includes
Write the left pointer of the block connected to the left side. Thus, the two blocks can be connected. The block combining process in FIG. 4 is performed independently for each of x and y in FIG.

When a packet having a sequence number of the next expected value at the input port x in FIG. 3 arrives, the block starting with the packet can be transferred to the output line (service is enabled). The service order is scheduled for such a service enabled block in block units. FIG. 5 shows the principle of scheduling. Each row of the block service order scheduling management table 4 has a left pointer and a right pointer of a service block. When a new block becomes serviceable (arriving), the left and right pointers are written to the next line.

The block service order management table 4 has a pointer to a block currently in service and a pointer to a newly arrived block. When all the packets in the block indicated by the pointer currently being serviced have been serviced, the process moves to the block in the next row.

FIG. 6 shows the principle of system selection for each packet from a duplicated switch network. In the figure, since the packet with the sequence number 95 has already been received, the packets with the sequence number 95 from the system 0 are discarded. The packet of sequence number 96 from the first system is received.

FIG. 7 shows the principle of failure detection in a switch network. A KeepAlive packet as a test packet is exchanged between the input port 1 and the output port 3. KeepAlive
Packets are sent to all routes and output port 3
Then, KeepAlive from all routes of both switch networks
Check if a packet has arrived. In this way, a route failure is monitored.

[0031]

As described above, according to the present invention,
Packets can be distributed to all routes connecting each input / output port, and the order of cells can be guaranteed by the sequence number. In addition, since the first one of the packets coming from both systems of the duplexed switch network is selected, the system can be selected for each packet, and the reliability can be maintained even if the switch network becomes large-scale. . The service can be continued as long as the unit switch at the same position in both systems does not fail. Further, by exchanging KeepAlive packets between each pair of input / output ports, a failure in the switch network is detected, so that a mechanism for failure detection and notification is not required in the switch network.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a packet switch according to the present invention.

FIG. 2 is a diagram showing a status of assigning a sequence number at an input port.

FIG. 3 is a diagram showing a packet rearrangement state at an output port.

FIG. 4 is a diagram showing pointers used for rearranging packets.

FIG. 5 is a diagram showing a block service order management table.

FIG. 6 is a diagram showing a system selection status for each packet.

FIG. 7 is a diagram showing a distributed fault monitoring situation.

FIG. 8 is a diagram showing a switch network interconnected in multiple stages.

FIG. 9 is a diagram showing a packet switch in which a plurality of switch networks are arranged in parallel.

[Explanation of symbols]

1 input port 2 ₁ , 2 ₂ switch network 3 output port 4 block service order management table

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Claims (3)

[Claims] 1. A packet switch comprising: an input port from which a packet arrives; a switch network for switching the packet according to its destination information; and an output port for outputting a packet switched by the switch network. Comprises means for assigning an identification code of the input port and a series of sequence numbers to the packet in accordance with the arrival order of the packet, and the output port arranges the order of the packets for each input port in accordance with the identification code and the sequence number A packet switch comprising means. 2. A plurality of said switch networks are arranged in parallel,
Means for copying packets by the number of the switch network, and means for distributing the copied packets to the plurality of switch networks arranged in parallel, wherein the means for adjusting the order comprises the same sequence number and input port. 2. The packet switch according to claim 1, further comprising means for discarding a packet arriving after the second packet when a plurality of packets having the identification code of (a) arrive. 3. A device for transmitting a test packet specifying a switching path from the input port to the output port, and receiving the test packet and determining whether there is a failure in the switching path. 2. The packet switch according to 2.