JPS63193640A - Packet by-pass system - Google Patents

Abstract

PURPOSE:To prevent slave routes from the influence of congestion by detecting a fault or congestion in a repeating route which is not recovered even after the passage of a prescribed time from the generation of the fault. CONSTITUTION:When a packet to an exchange 1e is reached to an exchange 1d, a fault/congestion monitoring part 4 in the exchange 1d monitors the states of respective repeating routes 2e, 2f, 2c, turns on corresponding display flags 3a-3c at the time of generating a fault or the like, and informas the monitored result to a fault/congestion continuation time monitoring mechanism 7. At the time of recovery also, similar information is executed. When a packet sending enable repeating route is only a route 6c with the lowest priority, the mechanism 7 starts a timer and regulates transmission from respective exchanges 1a-1f to the exchange 1e concerned in accordance with the time-out of the timer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for switching to a low-priority relay route that is a detour route when a failure state or a congestion state of a packet relay route continues for a long time. The present invention relates to a packet detouring method that can prevent packets from concentrating and causing even the relay route to become congested.

[Conventional technology]

Figure 4 shows, for example, the conventional packet bypass method described in "l'-3,5,1 routing" on pages 113 to 114 of "Packet Switching Technology and its Applications" (published by the Institute of Electronics and Communication Engineers). In the figure, 1 is a packet switching center, 2 is a relay route of this packet switching center 1, 3 is a routing table provided in the packet switching center 1, and 4 is a routing table provided in the packet switching center 1. A failure/congestion monitoring unit 5 monitors the failure state and congestion state of each relay route 2 and rewrites the routing table 3; 5 refers to the routing table 3 and selects the normal relay route 2 with the highest priority; This is a relay processing unit that selects a packet and relays the packet.

FIG. 2 shows a packet switching network formed by packet switching stations configured in this way.
1f is packet switching center A to packet switching center F, 2a to 2
h is the packet switching center A(1a) to packet switching center F
Relay routes 6a to 6C connecting between (1f) are routes A to C for sending packets destined for packet exchange E and (1e) from packet switching center p (1d). This route)A (6a) is a route that passes through relay route 2e with the highest priority, route B (6b) is a route that passes through relay route 2f with the next highest priority, and route)C (6c) is a route that passes through relay route 2e with the highest priority. is the route that passes through the lowest relay route 2C.

FIG. 3 is an explanatory diagram showing the structure of the routing table 3, and this figure shows the structure of the routing table 3 in the packet switching center D (1d). In the figure, 33 to 3C are failure/congestion display flags corresponding to the routes A (6a) to C (5c), respectively;
It is on when the corresponding route is in a faulty or congested state, and off when it is normal.

Next, the operation will be explained. For example, packet switching center D
When a packet addressed to packet switching center E (1e) arrives at (1d), relay processing unit 5 of packet switching center D (1d)
refers to the routing table 3 for packet switching center E (1e) and scans it in descending order of priority. At this time, route A (if the fault/congestion display flag 3a of 6ω is off, the packet is sent to the relay route 2e, and if the fault/congestion display flag 3a is on, route)
If the failure/traffic display flag 3b of B (6b) is off,
The packet is sent to the relay route 2f, and if the failure rumor congestion display flags 3a and 3b are both on and the failure/congestion display flag 3C of route C (6ψ) is off, the packet is sent to the relay route 2c. Fault/congestion display flags 3a to 3C
If all of the packets are on, the packet is discarded. Also,
The failure/congestion monitoring unit 4 monitors each relay route 'le, 'l'f,
Monitor the status of 2c, and when a failure or congestion occurs,
Turn on the corresponding failure/congestion display flags 3a to 3C,
When both the failure and the traffic are recovered, the failure/traffic display flags 3a to 3C are turned off.

[Problem that the invention seeks to solve]

Since the conventional packet detouring method is configured as described above, if the failure state or congestion state of the upper route due to the high priority relay routes 2e and 2f continues for a long time,
Many packets concentrate on the lower route using relay route 2C, which has a lower priority, and even the lower route becomes congested.
In addition, the congestion spreads to the detour optical packet switching center A (1a) and the relay route 2h beyond that, resulting in problems such as a significant increase in the time required for packet delivery.

This invention was made to solve the above-mentioned problems, and aims to provide a packet detouring method that can prevent the spread of congestion and an increase in packet delivery time. [Means for Solving the Problems] The packet detouring method according to the present invention provides a failure/congestion duration monitoring mechanism in the packet switching center, and monitors the relay route after a certain period of time has elapsed from the time when a failure or congestion occurs in the relay route. Also, when a failure or congestion is not recovered, the transmission of packets to the lower route is stopped and the transmission of packets to the corresponding destination is restricted.

[For production]

The packet detour method in this invention stops sending packets to the lower route when a failure or congestion on the upper route continues for a certain period of time from the point of occurrence, and restricts the transmission of packets to the corresponding destination. , which reduces the possibility that lower-level routes will fall into congestion from then on.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is a packet switching center, 2 is a relay route, 3 is a routing table, 4 is a failure/traffic monitoring unit, and 5 is a relay processing unit, which are the conventional ones with the same symbols as in Figure 4. Since this is the same or equivalent part, the explanation will be omitted. Further, 7 is provided in the packet switching center 1, and receives notification from the failure/congestion monitoring unit 4 of the time when a failure or congestion occurs in each route and the time when normality returns.
This is a fault/congestion duration monitoring mechanism that monitors congestion duration, and is configured with simple software, for example.

Next, the operation will be explained. Packet switching center D in Figure 2
When a packet addressed to the packet switching center E (1e) arrives at (1d), the operation of the relay processing unit 5 of the packet switching center o (1d) is the same as in the conventional case. The failure/congestion monitoring unit 4 monitors the status of each relay route 2e, 2f, 2c, and when a failure or congestion occurs, turns on the corresponding failure/congestion display flags 3a to 3c, and also detects the failure. - Notify the congestion duration monitoring mechanism 7 to that effect. In addition, when both the failure and congestion are recovered, the failure/congestion display flag 3a
~3C is turned off, and the fault/congestion duration monitoring mechanism 7 is notified of this.

The failure/congestion duration monitoring mechanism 7 includes the failure/congestion monitoring unit 4
When the occurrence of a failure or congestion is notified by K, it is determined whether or not the only relay route that can send the packet is C (6C), which has the lowest priority. For example, a timer (not shown) is activated. When this timer measures a certain period of time and detects that it has timed out, the failure/congestion duration monitoring mechanism 7 sends a request to each packet switching station 1a to 1f in the packet switching network to the corresponding packet switching station (in this case, A restriction is placed so that packets are not sent to packet switching center E (1e).When notification is received that both the failure and congestion have been recovered, the above-mentioned timer is activated. If it is in operation, it is stopped, and if communication to the corresponding packet switching center is being restricted, the restriction is lifted.

Note that in the above embodiment, failures and congestion are treated in the same way, but in the case of congestion, it is not impossible to send packets at all. The congestion state of the strategy may be released.

〔Effect of the invention〕

As described above, according to the present invention, obstacles and
A congestion duration monitoring mechanism has been installed to detect failures or congestion in relay routes that do not recover even after a predetermined period of time has elapsed from the time of occurrence, so if a failure or congestion in the upper route continues for a long time. However, it has the effect of preventing congestion from spreading to lower routes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a packet switching station that uses a packet detour method according to an embodiment of the present invention, FIG. 2 is a system diagram showing an example of a packet switching network to which this invention is applied, and FIG. 3 is a routing table. FIG. 4 is an explanatory diagram showing the configuration of a packet switching center that employs a conventional packet detour method. 1.1a to 1f are packet switching stations, 2 and 2a to 2h are relay routes, 3 is a routing table, 3a to 3C are fault/congestion display flags, 4 is a fault/congestion monitoring unit, and 7 is a fault/congestion monitor.
Congestion duration monitoring mechanism. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] The packet switching station is equipped with a routing table for determining the relay route for relaying and transmitting packets, and in this routing table, the relay routes selected for each destination station are arranged in order of priority, and the failure status is determined for each route. Alternatively, a flag indicating the presence or absence of a congestion state is provided, and the relay route with the highest priority where neither failure nor congestion has occurred is selected by referring to the flag in this routing table, and the packet is relayed. In the packet detour method of a packet switching network that uses a fixed detour method to send out,
The packet switching center is provided with a fault/congestion duration monitoring mechanism, and when the fault/congestion duration monitoring mechanism detects that a fault state or a congestion state has continued for a certain period of time in the relay route with a high priority, A packet detouring method characterized in that relay transmission to the relay route having a low priority is stopped and transmission of the packet to the corresponding destination is restricted.