JPS60177761A - Congestion control system in packet switching network - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (al) Technical Field of the Invention The present invention relates to a packet-switched network, and particularly relates to a congestion control method in a packet-switched network that enables shortening of packet transfer time and load distribution within the packet-switched network. .

Technical background FIG. 1 is a diagram showing an example of a packet switching network to which the present invention is applied. In FIG. 1, the packet switching network is comprised of a plurality of packet switches A to E. Each of the packet switches A to E has a plurality of routes corresponding to each destination station. For example, when packet switch C is the destination station, packet switch A has two types of routes: a relay route L2 leading to packet switch B and a relay route L3 leading to the packet switch 2, and the congestion state of each route The communication status, reliability, and economic efficiency of the packet switching network are improved by selecting the network according to the situation.

(C) Prior Art and Problems FIG. 2 is a diagram showing an example of a conventional congestion control system in this type of packet switch. In Figure 2, the first
The explanation will be given using the packet switch A shown in the figure as an example. The packet switch A includes a communication device CMU that sends and receives packets to and from each relay path L1 to L3, a central control device CC that controls packet transfer, a bucket sofa that temporarily stores transferred packets, and a central control device CC that sends and receives packets to and from each relay path L1 to L3. The main storage device MM is provided to store various information necessary for controlling the transfer of the data. The main storage device MM has a route selection table (hereinafter referred to as a routing table).
L is provided, and route identification information rn indicating a route corresponding to each destination station indicated by destination station information dn and route blockage information rb indicating whether each route is in a state of conflict are stored. ing. For example, for destination station information dn=C, information on relay routes L2 and L3 is stored as route identification information rn, and if each relay route L2 and L3 is brought into a congested state, the route blockage unit MB stores route blockage information. rb is set to a logical value O, and if there is a congestion state, the route blocking unit MB sets route blocking information rb'4c to a logical value 1. Now terminal device T1
When the sender sends a packet to the terminal device T3 accommodated in the packet switch C, the originating node switch 1 adds destination station information dn=C to the received packet and sends it into the packet switch network. When the packet arrives at the packet exchange iA via the relay path L1, the route selection unit SEL provided in the central controller CC extracts the destination station information Qjdn=C from the received packet, and stores it in the routing table in the main memory MM. First, the logical value of the route blockage information rb corresponding to the route identification information rn=L2 is identified by referring to the destination station information dn=c corresponding section of the location. If the current relay route L2 is not in the congestion state and the corresponding route blockage information rb is set to a logical value of 0, the route selection unit SEL selects the relay route L2 as the transfer route for the received packet. On the other hand, when bucket switch B detects a congestion state such as a lack of packet buffers due to an abnormal increase in incoming packets or an overload on the central control unit, it sends a congestion state to all neighboring packet switches A, C, D, and E. transmits a packet that notifies the When the packet switch A receives the congestion notification bucket from the packet switch B, the route block block MB provided in the central controller CC generates route block information corresponding to the relay path L2 leading to the packet switch B in the routing table. Set rb to logical 1. When a packet having destination station information dn-C is received from relay path L1 in such a state,
The route selection unit SEL refers to the destination station information dn=C corresponding section of the routing table TBL in the same process as described above, and since the route blockage information rb corresponding to the relay route L2 is set to logical value 1, the route selection unit SEL selects the relay route. It recognizes that L2 is in a blocked state, and then refers to route blockage information rb corresponding to relay route L3. If the relay route L3 is not in a congested state and the corresponding route blockage information rb is set to the logical value O, the route selection unit SEL selects the relay route L as the transfer route for the received packet.
Select 3.

As is clear from the above explanation, in a conventional congestion control system, an adjacent packet switch (for example, A) that receives the congestion notification packet 7 from packet switch B connects a relay route (for example, L2) to packet switch B. It is set in a blocked state and all packets passing through the packet switch B are detoured to another packet switch S (for example, D). As a result, not only does the transfer time of all detour packets increase, but the packet switch that received the detour packet (for example, D) becomes further in a congestion state, which has the disadvantage that the congestion state spreads to the entire packet switching network. there were.

(dl Object of the Invention) An object of the present invention is to eliminate the drawbacks of the conventional congestion control method as described above, and to prevent relay stations from controlling congestion for specific packets, such as packets transmitted by particularly important terminal devices. without increasing the time required for transfer even if the
Another object of the present invention is to realize a means for preventing the congestion state from spreading to the entire packet switching network as much as possible.

(e) Structure of the Invention The purpose of this invention is to add detour restriction information to packets 7) sent to the destination station by the originating packet switch in a packet switching network that has a plurality of packet transfer routes via relay packet switches for the destination station. When the relay packet switch receives the Pagaso 1-, the relay packet switch establishes a route for transmitting the packet based on the detour restriction information added to the packet and the congestion status information of the adjacent bucket switch on the route to the destination station. This is achieved by determining the

That is, in the present invention, the originating bucket switch adds detour control information to distinguish specific packets, such as those transmitted from important terminal equipment, from general packets, and transfers them to the relay bucket switch, and the relay packet switch transfers the packets to the relay bucket switch, and the relay packet switch receives the packets. In order to determine whether detouring is necessary by identifying the detour restriction information attached to the packet, only the specific packet is sent to the destination station via the normal shortest transfer route without detouring through the relay station in the congested state. This will be communicated to

(fl　Embodiments of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing a transfer packet according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a congestion control method based on traffic type according to an embodiment of the present invention. Note that the same reference numerals refer to the same objects throughout the plan. The target packet switching network is the one shown in FIG. 1 as an example. In FIG. 3, in addition to destination station information dn and originating station information On, detour restriction information cr is added to the terminal's transmission packet pkt. The detour restriction information cr is set to a logical value O for general packets that are to be detoured to a bucket switch that is in a congested state, and is set to a logical value O for a general packet that is to be detoured to a packet switch that is in a congested state. is set to a logical value of 1 for packets of . In addition, in FIG. 4 illustrating the packet switching equipment A in FIG. The routing table TBL' in the main memory device MM includes destination station information 91dn and route identification information rn.
In addition to route blockage information rb, adjacent station information tn and congestion information cng are stored.

The adjacent station information tn is information indicating adjacent stations connected by the relay route indicated by each route identification information rn, and the congestion information cng
is information indicating the congestion state of the adjacent station packet switch. For example, in the destination station information 91dn=C corresponding section, adjacent station information tn=B corresponds to route identification information rn-L2, and adjacent station information tn=B corresponds to route identification information rn=L3.
n=D is accommodated. Neighboring station comparison status within central controller CC! 3 identification unit CNG uses adjacent station information tn=B and The congestion information cng corresponding to D is set to a logical value of 0, and when the congestion notification packet/node is transmitted, the congestion information cng is set to a logical value of 1.
Set to . When the terminal device T1 now sends a packet to the terminal device T3 accommodated in the packet switch C, the originating packet switch 1 determines that the terminal device T1 is a terminal device that transmits general packets, and the received packet )
1, detour control information cr=o is added together with destination station information dn=C, and the information is sent into the bucket switching network. When the packet arrives at the packet switch A from the relay path L1, the detour restriction information detection unit CR provided in the central control unit CC detects the detour restriction information ta cr 7 included in the received packet.
! The route selection unit SE identifies that l<logical value O, and if the packet switch indicated by the adjacent station information tn is in a conflicting state, the route selection unit SE determines that the packet requires a detour.
Notify L'. As a result, the route selection unit SEL' selects the destination station information Q[1dn=
Referring to the C corresponding section, first identify the logical value of the contrast information cng corresponding to the route identification information rn=L2, and if it is set to the logical value O, the packet/7to switch B is in the contrast state. It is determined that there is no one, and after confirming that the route blockage information rb is set to the logical value O as described above, the relay route L2 is selected as the transfer route for the received packet. On the other hand, if the congestion information cng is set to the logical value 1, the route selection unit SEL' determines that the packet switch B is in a congestion state, and the destination station information d
Comparison information c corresponding to the next relay path L3 from the n=C corresponding part
The logical values of ng and route blockage information rb are sequentially identified, and if it is confirmed that both are set to a logical value of 0, the relay route L3 is selected as the transfer route for the received packet. Next, when the terminal device T2 transmits a packet to the terminal device T4 accommodated in the packet switch C, the originating packet switch (not shown) determines that the terminal device T2 is the terminal device transmitting a specific packet, and sends a packet to the received packet. The detour restriction information cr set to logical value 1 is set as the destination station information dn=C
It is added together with the packet and sent out within the packet switching network. When the packet arrives at the bucket exchanger A from the relay path L1, the detour restriction information detection unit CR provided in the central control unit CC
identifies that the detour restriction information cr included in the received packet is set to a logical value of 1, and that the packet is not to be detoured even if the packet switch indicated by the adjacent station information tn is in a conflicting state. is notified to the route selection unit SEL'. As a result, the route selection unit SEL" refers to the destination station information dn=C corresponding section of the routing table TEL based on the extracted destination station information dn=C, and selects the route identification information rn.
= The logical value of the route blockage information rb corresponding to L2 is the logical value O
After confirming that this is set, the relay path L2 is selected as the transfer route for the received packet regardless of the congestion state of the packet switch B.

As is clear from the above explanation, according to this embodiment, the relay packet switch A uses the detour control information c of the arriving packet.
If r is identified and set to logical value 1, the packet is sent to relay path L2 even if a comparison notification bucket is received from bucket switch B. As a result, the bucket is transferred to the destination packet switch C via the shortest route as in the case where the bucket switch B is not in the state of contention. The load within the packet switching network is also distributed.

Note that FIGS. 3 and 4 are only one embodiment of the present invention, and for example, detour control information CR or congestion reduction information CNG
is not limited to two stages, and may be set to three or more stages, but the effects of the present invention remain the same in either case. It goes without saying that the configuration of the packet switching network to which the present invention is applied is not limited to that shown in the drawings.

(gl) As described above, according to the present invention, in the packet switching network,
Even if a relay station is in a state of congestion, specific packets can be forwarded using the normal shortest route, without increasing the time required for forwarding, and preventing congestion from spreading to the entire packet switching network. is also prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a packet switching network to which the present invention is applied, and FIG. 2 is a diagram showing an example of a conventional congestion control method.
FIG. 3 is a diagram showing a transfer packet according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a congestion control method depending on the traffic type according to an embodiment of the present invention. In the figure, A to E are bucket switches, cc is a central control unit, CMU is a communication device, CNG is an adjacent channel width light state identification unit, cn'g is congestion information, CR is a detour restriction information detection unit, and cr is a Detour regulation information, dn is destination station information, Ll to L8 are relay paths, MB is route blocking section, MM is main storage,
on is source station information, pk, t is a packet sent by the terminal, rb is route blockage information, rn is route identification information, SEL and SEL' are route selection units, T1 to T4 are terminal devices, TBL and TBL' are routing table, tn
vine 1 ■ ``f 〆茅 2 fig.

Claims (1)

[Claims] In a packet-to-node switching network that has multiple packet transfer routes to destination stations via relay packet-to-node switches, the originating packet switch adds detour restriction information to packets destined for the destination station and sends them to the relay packet-to-node switch. When the packet is received, the packet switching device determines a route for transmitting the packet based on the detour restriction information added to the packet and congestion state information of an adjacent packet switch on the route toward the destination station. Convergence control method in networks.