JPH01225262A - Packet communicating system - Google Patents

Abstract

PURPOSE:To realize the service of a low delay time and a low abandon rate by independently and variably setting the allocation of buffer capacity, reading priority and link capacity with being matched to the request condition of a service class respectively. CONSTITUTION:For example, capacity B1 is set to a buffer 1 and a buffer 3, to which the low abandon rate is requested, and capacity B2 is set to a buffer 2, to which the low abandon rate is not requested. Reading devices 4, 5, 6 and 7 are connected to the buffer 1, the reading devices 4 and 5 are connected to the buffer 2 and the reading devices 6 and 7 are connected to the buffer 3 respectively. Thus, the link capacity of the buffer 1 to the packet is set to an L1 and the link capacity to the buffers 2 and 3 is set to an L2. Accordingly, by setting buffer capacity B1, the link capacity L1 and reading priority 1 to a call type 1, the service class of the low delay time and low abandon rate can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides
Efficient and highly flexible packet communication method % (Conventional technology) When performing packet multiplex communication, the conventional A method for realizing the requirements of the various service classes currently available will be explained with reference to FIG. This is a method in which a buffer with a different capacity is provided for each service class to be accommodated in a forwarding node, and reads to links are prioritized to achieve the required delay time and packet discard rate. Here, symbols used in the following explanation will be explained. There are two types of buffer capacity: capacity B
1 is larger than the capacity B2. There are three types of read priorities, and the smaller the number, the higher the priority. Further, there are two types of link capacities, and capacity L1 is larger than capacity L2. 1st
In the figure, a buffer 2 with a capacity of B2 is provided and a read priority of 1 is set for call type 2, which belongs to a service class that requires only a low delay time and is relatively tolerant of drop rates. As a result, each node discards packets that exceed the delay time allowed at the node for that service class, and unnecessary packets that are delayed at a node beyond the allowable value are not transferred within the network. On the other hand, for call type 3, which belongs to a service class that is relatively tolerant in terms of delay time but strict in terms of drop rate, read priority 2 is set, but buffer 3 with capacity B1 is provided. This is a control method that reduces the discard rate and achieves the requirements of the service class.

(Problem to be solved by the invention) However, when accommodating call type 1 belonging to a service class that requires both low delay time and low discard rate, this can be achieved by increasing the buffer capacity and increasing the read priority. However, if you set buffer 1 with a capacity of B1 and read priority 1 for call type 1, and read out randomly or sequentially with call type 2, the buffer size will be lower than that of call type 2. The discard rate decreases as the capacity increases, but delay time is generally inversely proportional to readout speed, so if the link capacity remains the same as call type 2, the delay time will be larger than call type 2. Put it away. In addition, when reading priority O is set, the buffer for call type 1 is large, and reading of call type 2 is performed after reading of call type 1 is completed, so the delay time for call type 2 is low. It becomes impossible to realize this. In this way, conventional priority control techniques have the disadvantage that it is difficult to accommodate service classes that require low delay time and low drop rate at the same time.
Furthermore, since the control range is limited to the buffer capacity and read order, it is difficult to set flexible priority control.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a highly flexible priority control method that can accommodate service classes that require both low delay time and low discard rate, which are disadvantages of conventional methods.

(Means for Solving the Problems) A feature of the present invention for achieving the above object is to transfer packets by packet multiplexing via a plurality of relay nodes,
For transfer, in a packet multiplex communication network that provides multiple service classes, a waiting buffer is provided for each type of service class at each transfer node to handle packets belonging to different service classes, and generally the packets are assigned different buffer capacities, read priorities, and , a packet communication method in which link capacity allocation is independently and variably set according to the requirements of each service class.

In particular, an important feature of the present invention is that it is possible to control not only buffer capacity and read order but also link capacity for each service class type.

(Embodiment 1) An embodiment of the priority control system of the present invention will be described with reference to FIG. Here, an example that accommodates the following three types of service classes will be described. In the same figure, 1 is the name type 1
2 indicates a buffer for call type 2, and 3 indicates a buffer for call type 3. Here, call type 1 belongs to a service class that requires low delay time and low drop rate, and call type 2 belongs to a service class that requires low delay time but is tolerant of drop rate. Type 3 belongs to a service class that is tolerant of delay time but requires a low drop rate.

In this embodiment, nodes are connected by a plurality of links, and a reading device is provided for each link.

FIG. 2 shows an example in which four reading devices are provided. Here, reference numerals 4, 5, and 6.7 are reading devices, each of which is connected to a link, and sends out packets in the buffer to the link.

Capacity B1 is set for buffers 1 and 3 that require a low discard rate, and capacity B2 is set for buffer 2 that does not require a low discard rate.

And buffer 1 is 4, 5, 6, 7, buffer 2 is 4
, 5, and buffer 3 is connected to 6 and 7, respectively. That is, the link capacity for packets in buffer 1 is L
The link capacity for packets of L, Buffer 2, and Buffer 3 can be set to L2. Regarding read priority, priority 1 is set for call types 1 and 2 that require low delay time, and priority 2 is set for call type 3 that does not require low delay time. Set. Call type 1 and call type 2 are set to be read out randomly or sequentially with the same priority. In this way, for call type 1, the buffer capacity Bl,
By setting link capacity L1 and read priority 1, a service class with low delay time and low drop rate can be realized. For call type 2, buffer capacity MB2
, link capacity L2, and read priority 2, it is possible to realize a service class that has low delay time but is tolerant of discard rate. Also, call type 3
By setting the buffer capacity B1, link capacity L2, and read priority level 2, it is possible to realize a service class that is tolerant of delay time but has a low discard rate.

(Example 2) In Example 1, link capacity was set spatially by preparing multiple links between nodes, but in Example 2, link capacity was set temporally for time-division multiplexed links. The case where allocation is performed will be explained using FIGS. 3 and 4.

8 is a time-division multiplexed link, and a plurality of time slots constitute an l frame. FIG. 3 shows an example in which one frame is composed of four time slots.

To make this work, for example, for buffer 1, allocate four time slots (a, b, c, d) to increase the equivalent speed of the read link, and set a read priority of 1. For buffer 2, two time slots (a, b) are allocated and a read priority of 1 is set. Then, for buffer 3, two time slots (c, d) are allocated and read priority level 2 is set. That is, for time slots a and b, buffer 1
, the packets in buffer 2 are read out randomly or sequentially, and for time slots c and d, buffer 1 is read with higher priority than buffer 3, thereby achieving low delay time and low latency for call type 1. It is possible to realize a service class with a low drop rate, a low delay time for call type 2, and a low drop rate for call type 3. In the above embodiment, an example is shown in which bit multiplexing is used as multiplexing to a link, but word multiplexing or packet multiplexing can also be performed in the case of fixed length packets within a frame.

(Effects of the Invention) As explained above, the present invention enables setting different buffer capacities, read priorities, and link capacities for each service class in a forwarding node of a packet multiplex communication network according to required conditions. This makes it easy to realize service classes with low delay time and low drop rate.
It has the advantage of allowing highly flexible priority control.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the prior art, FIG. 2 is an explanatory diagram of Embodiment 1 of the present invention, FIG. 3 is an explanatory diagram of Embodiment 2 of the present invention, and FIG.
The figure is an explanatory diagram of Example 2 of the present invention. 1.2.3--buffer, 4.5,6.7--reader, 8-link, 9-time slot,
lO...Frame, 11...Exchange.

Claims (3)

[Claims] (1) In a packet multiplex communication network in which packets are transferred via packet multiplexing via multiple relay nodes and multiple service classes are provided for transfer, packets belonging to different service classes are transferred to each forwarding node according to the type of service class. A packet communication method characterized in that a waiting buffer is provided for each service class, and generally different buffer capacities, read priorities, and link capacity allocations are independently and variably set in accordance with the requirements of service classes. (2) A plurality of links are provided between nodes, and in the transfer node, a buffer with a required capacity is provided for each call type of a different service class, and reading from each buffer to the link is prioritized, The packet communication method according to claim 1, characterized in that the transmission conditions required for each service class are realized by transmitting the communication to one or more designated links from among the plurality of links stretched between the nodes. . (3) Configure a time-sharing frame on the link between nodes,
In the transfer node, a buffer with the required capacity is provided for each call type of different service classes, and reading from each buffer to the link is prioritized and the number of time slots in the frame is assigned. 2. The packet communication system according to claim 1, wherein by specifying a different link capacity for each service class, it is possible to set a different link capacity for each service class, thereby realizing transmission conditions required for each service class.