JPS60212053A - Packet exchange relay line selecting system - Google Patents

Abstract

PURPOSE:To reduce the delay time in a network by assinging a number at each logical link at each calling in a calling exchange station, allowing the calling exchange station to set this number in a head of all packets of the succeeding call and using this number at the selection of transmission line at the calling exchange station or a relay exchange station and deciding the transmission line so as to decentralize the loads. CONSTITUTION:Relay path numbers viewed from an exchange P are represented by R1, R2, R3 and R4 in a packet exchange P. Two-three relay lines Lij (i=1- 4, j=1-3) are set to the paths R1, R2, R3 and R4. In receiving a packet from a line L11, a path selection table T0 is indexed from a destination station number (a) of the packet so as to identify a transmission path number (R4) and a line selection table of the transmission path R4 is obtained. Then the line selection table T4 is indexed by a CIDX(3) to obtain a line number L42 to transmit the packet. That is, the calling exchange station provides 0-7 numbers of modulo 8 to a call transmitted from the exchange station in order, then each line is used in order in the units of a call by the line selection table T4 and uniform loading is attained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a method for transmitting packets to other stations in a packet switching network from among a plurality of relay lines set up between the other stations. The present invention relates to a packet switching trunk line selection method suitable for selecting lines so that each line is used equally.

[Background of the invention]

General number: In a packet switching network, multiple relay lines are set up between switching stations to ensure throughput and maintain reliability. When a switching station sends a packet to another station, it first determines the relay route based on the destination information in the packet header, and then determines the line number (
Determine the outgoing line number).

When determining the transmission line, consideration must be given to ensuring that multiple lines are used as evenly as possible in order to reduce the delay time of packets within the network.

Conventionally, when a packet transmitting station or a packet relay station sends a packet to a relay line, a method has been adopted in which the outgoing line is randomized based on the line number (incoming line number) from which the packet entered the switching station. That is,
When selecting a strategic line after determining the strategy, the exchange uses the incoming line to determine the outgoing line.

FIG. 1 is a configuration diagram of a switching network for explaining the logic for selecting trunk lines according to the above method.

In FIG. 1, P is a packet switch, R1, R
2, R3, and R4 are relay route numbers 1 seen from the exchange P. In addition, each route R1, R2, R3, R4 has 2 to
Three lines (LIJ-1=1 to 4, j=1 to 3) are set.

FIG. 2 shows the structure of the strategy/line selection table in the switching network of FIG. This is a selection table, and T4 is an example of a line selection table for setting the outgoing line number of the line to be sent out from among the lines directed to route R4. Furthermore, HLN
' is the remainder when the line number HLN of the incoming line is divided by the number of outgoing lines.

Next, a conventional strategy/line selection processing method will be explained with reference to FIG.

First, when a packet is received from a line, the number HLN of the line (incoming line) from which the packet was transmitted is set in the header of the packet (301.302). Next, the destination station number a is extracted from the packet, and the route selection table TO shown in FIG. 2 is indexed using the destination station number a to obtain the route number (303, 304). Once the route number is obtained, it is recognized that the packet should be sent along the route indicated by that number. Furthermore, in order to determine the sending line from among the multiple lines set within that route, the line selection table corresponding to the route is accessed, and the H
Obtain the outgoing line number (L, J) by indexing by LN' (
305). The packet is sent to the line indicated by Ll (306).

Specifically, a packet arriving from line Lll and transferred to route 4 will be explained as follows.

When exchange P receives a packet from line Lll, it extracts the destination number a from the header of the packet, and
The route selection table TO is indexed using this number. According to FIG. 2, when the value T4 is obtained, it is recognized that this packet is a packet to be sent to strategy number R4.
Next, access the line selection table T4 and select the incoming line number H.
The LN is indexed by the remainder (HLN') obtained by dividing the number of outgoing lines set for the relevant outgoing route (R4). If this remainder is 1, a sending line of sight L42 is obtained as shown in FIG.

In this way, in the conventional system, traffic randomization is performed for each incoming line, and all packets with the same incoming line number and the same outgoing route are sent to the same relay line. become.

Therefore, the conventional method has the following problems.

(1) If the number of incoming and outgoing lines is different, such as when the number of incoming lines is 3 and the number of outgoing lines is 2, the load on the outgoing lines will be unbalanced.

(2) When incoming lines include lines whose line speed is higher than other incoming lines, a large load is placed on a particular outgoing line.

Specifically, looking at the packets transferred from route R to R4 in Figure 2, those from line Lll are transferred to R4.
42 is selected, and those from L12 are L4L, Ll3
R42 will be selected for those from . In other words, the load on one line R42 is twice that of R41.

Furthermore, if Lll is several times faster than other incoming lines, R42 will have a load several times greater than R41.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art as described above, and to reduce packet traffic (load) even when the numbers of incoming and outgoing lines are different or the line speeds of incoming lines are uneven. An object of the present invention is to provide a packet-switched relay line selection method that can select a relay line so as to evenly distribute the information.

[Summary of the Invention] In order to achieve the above object, a packet switching trunk line selection method according to the present invention is provided in a packet switching network.

At the originating exchange, a number is assigned to each logical link (call) at the time of origination of each call, and the originating exchange sets this number in the header of all subsequent packets of the call. By using this number when selecting the sending line in , the sending line is determined so that the load is distributed.
The feature is that it reduces the delay time within the network.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 4 is a configuration diagram of a switching network for explaining the trunk line selection logic according to an embodiment of the present invention.

P is a packet switch, and R1, R2, R3, and R4 are relay route numbers seen from the switch P. Also, each direction R
1, R2, R3, and R4 have 2 to 3 relay lines.
(+=1 to 4, j=1 to 3) are set.

Incidentally, CIDX is a number given to each call by the originating exchange in modulo N (modulo 8 in this embodiment) at the time of call origination, and is set in the header of all subsequent packets of the call.

Here, modulo is an arithmetic operation method in which the result is the remainder when the first number is divided by the second number. Generally, when adding or subtracting modulo N, the value is 0.1.
Since it is 2,...,N-1.

The modulo 8 values are 0.1.2.3, 4.5.6.7.

FIG. 5 shows the structure of the strategy/line selection table in the exchange P of FIG. 4.

TO is a strategy selection table for determining the relay route number to which the packet should be sent from destination a in the packet header, and T4 is the outgoing line number of the line to be sent from among the lines destined for route R4. This is an example of a line selection table for selecting a line.

The contents of the line selection table T4, which is alternately repeated as R41, R42, R41, etc., are the CIDX value,
That is, it corresponds to the value of modulo 8, Oll, 3°, . . .

With the above configuration, the exchange P operates as shown in the flowchart of FIG.

First, when a packet is received from one line, the number CIDX assigned by modulo N when setting up the logical link (call) is set in the header of the packet (601.602).
. Next, the destination station number a is extracted from the packet, and the route selection table TO shown in FIG. 5 is indexed using the destination station number a to obtain the route number (603, 604). Furthermore, access the line selection table corresponding to this route number and
8. Index with DX and get the outgoing line number. is obtained (605).

The packet is sent to the line indicated by Ll (
606).

Next, the above operation will be explained using a specific example.

Upon receiving a packet from line Lll, exchange P uses the destination station number a of this packet to select route selection table TO.
, and recognize the sending route number (R4 in this case).
A line selection table T4 for the sending route R4 is obtained. Next, set the line selection table T4 to CIDX (in this example, 3)
, and obtain the line number L42 for sending the packet.

In other words, if the originating exchange sequentially assigns numbers from O to 7 in modulo 8 to the calls made at the exchange, the line selection table T4 allows each line to be used in turn for each call, so that the numbers are evenly distributed. The line number of the incoming line has no effect on the selection of the outgoing line. This will be explained with the following example.

Line L11. Among the packets from L12 and Ll3, C
Those with IDX of O12, 4, and 6 are sent from line L41, and those with C and IDX of 1.3.5.7 are sent from line L4.
Sent from 2. For example, a packet from line Lll may be sent out from line L41 or from line L42 depending on the value of CIDX.

In this way, the correspondence relationship between incoming lines and outgoing lines is not fixed, and each incoming line and outgoing line is a variable number that is sequentially assigned by the originating exchange to calls made at that exchange. can be mapped to Therefore, even if the numbers of incoming and outgoing lines are different, it is possible to equalize the number of times each outgoing line is selected.

In the conventional system, as shown in FIG. 1, packets from one line L11 were always sent out from line L42.
In this embodiment, packets from line Lll are
If IDX is an odd number, it is sent from line L42, and CID
If X is an even number, it will be sent from line L41, so Ll
Even if l is several times faster than other incoming lines, the load on R41 and the load on R42 can be equalized compared to the conventional example.

If there is a difference in line speed between the outgoing lines, the frequency of occurrence of the line number set in the line selection table T4 is made proportional to the outgoing line speed, so that the outgoing line speed can be taken into account. Traffic can be applied to each line as evenly as possible.

The strategy selection table TO shown in FIG. 5 may be provided on each side of each packet switch in the packet switch network.
A line selection table must be provided for each route.

〔Effect of the invention〕

As explained above, according to the present invention, even when the number of incoming and outgoing lines is different or the line speeds of incoming lines are uneven, packet traffic can be distributed evenly to each relay line. It is possible to shorten the delay time within the network.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of trunk line accommodation to explain conventional strategy/line selection, FIG. 2 is a conventional strategy/line selection table, and FIG. 3 is a diagram of an exchange line according to an embodiment of the present invention. Float yard showing the selection operation, FIG. 4 is a diagram showing an example of trunk line accommodation to explain route/line selection according to an embodiment of the present invention, and FIG. 5 is a diagram showing a route according to an embodiment of the present invention. - Line Selection Table FIG. 6 is a float yard showing the line selection operation of the exchange according to an embodiment of the present invention. P: Packet switch, R1, R2, R3, R4: Route number, TO two-way selection table, T4: Line selection table, LLl to L43: Trunk line number, a: Packet destination station number, HLNj input line number , CI DX: A number assigned to each call, modulo N, by the originating exchange at the time of origination. Figure 1 Figure 2 Figure 3 Figure 4 Figure P Figure 5 Figure 4 Figure 6

Claims (1)

[Claims] (1) In a packet-switched network, the originating exchange assigns a number to each logical link (call) when each call is originated, and the originating exchange sets the number in the header of all subsequent packets of the call. . A packet switching relay line selection method, characterized in that the number is used to select an outgoing line at an originating switching center or a relay switching center so as to distribute the load in units of logical links (calls).