CN1870546A - Method for obtaining communication system channel state - Google Patents

Abstract

The invention discloses a method for obtaining the channel state of a communication system, which comprises the following steps: 1) detecting information that the channel state has changed; 2) starting a timer to start counting; 3) continuing to detect the channel state until the time counted by the timer The time is equal to the preset time T, and the current channel state is obtained. By implementing the present invention, when the channel state changes, start the timer, shield the frequent DOWN/UP messages in a short period of time, wait for a period of delay, and obtain a stable channel state after the network tends to be stable, avoiding instantaneous interruption of the network Response to reduce the impact of frequent oscillations on the application.

Description

A method for obtaining channel status of a communication system

technical field

The invention relates to data communication technology, in particular to a method for obtaining channel status of a communication system.

Background technique

With the development of communication technology, how to quickly detect communication failures between adjacent systems, and how to quickly establish alternative channels or switch to other links when a failure occurs has become an important problem to be solved urgently.

BFD (Bidirectional Forwarding Detection, bidirectional forwarding detection), as a fast detection mechanism, came into being. BFD can detect faults on any type of path between systems, including virtual circuits, tunnels, MPLS (Multi-Protocol Label Switching) LSP (Label Switching Path), and multi-hop routing paths.

After a BFD session is established, it periodically sends BFD control packets to the peer end, and at the same time periodically checks the BFD control packets received from the neighbor. If the neighbor's packets are continuously lost, the link is considered to be down. The detection interval is negotiated through the BFD session. Currently, the interval can reach the microsecond level. When BFD detects that the link is down/up, it notifies the application of the link status update. It is up to the application to decide how to handle link state changes. The applications here can be interface management, VRRP (Virtual Router Redundancy Protocol, Virtual Router Redundancy Protocol), IS-IS (Intermediate System-Intermediate System) protocol, OSPF (Shortest Path Open First Protocol), LSP, etc.

BFD supports a wide range of applications, and different applications have different requirements. Some applications want to respond to link changes at any time, while others may not need to respond quickly to link changes. Unnecessary application actions are used to avoid network oscillations caused by frequent responses. Oscillations of some routing protocols will cause a great consumption of resources such as CPU and memory, and a large number of routing protocol update messages will cause a waste of bandwidth.

Contents of the invention

The purpose of the present invention is to provide a method for obtaining the channel state of a communication system in order to solve the problem of frequent response of applications when the channel is momentarily broken.

In order to achieve the above object, the present invention proposes a method for obtaining the channel state of a communication system, comprising the steps of: 1) detecting information that the channel state changes; 2) starting a timer to start timing; 3) continuing to detect the channel state, Until the time counted by the timer is equal to the preset time T, the current channel status is obtained.

After the step 3), the following step is also included: notifying the corresponding application of the current state of the channel.

After the step 3), the following step is also included: the corresponding application responds according to the channel state.

The change of the channel state in the step 1) is: from UP to DOWN or from DOWN to UP.

The range of the preset time T in the step 3) is: 1 minute≤T≤60 minutes.

In the step 1) and step 3), a bidirectional forwarding detection BFD mechanism is used to detect the channel state.

The present invention provides a WTR (Wait To Restore) mechanism for channel detection in a communication system. When the channel state changes, a timer is started to shield frequent DOWN/UP messages in a short period of time. After a period of delay, the network After it tends to be stable, a stable channel state is obtained, which avoids responding to network transients, reduces the impact of frequent oscillations on applications, and improves the stability of the communication system.

You can control the time to report the channel status to the application, wait for a period of time, and then notify the application of the channel status after the network stabilizes; you can also control the status of the channel by implementing the timer function at the application layer The response time is delayed for a period of time. After the network becomes stable, the application will respond to the status of the channel to improve the flexibility of channel status acquisition, notification or response.

The preset time of the timer is between 1 minute and 60 minutes. When the delay time is too short and less than 1 minute, the channel status cannot be stabilized; if the delay time is too long and longer than 60 minutes, the channel status cannot be adjusted in time. The detection result responds, thus losing the significance of detecting the channel.

Description of drawings

The present invention will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings.

Fig. 1 is a schematic flow chart of the present invention.

Fig. 2 is a schematic diagram of the system structure of the embodiment of the present invention.

Detailed ways

A method for obtaining communication system channel state, as shown in Figure 1, comprises the steps:

1. Detect channel status;

2. If a change in the channel state is detected, start the timer to start counting; if no change in the channel state is detected, continue to detect the channel state;

3. After starting the timer, continue to detect the channel state until the time counted by the timer is equal to the preset time T, and notify the corresponding application of the current state of the channel or the corresponding application responds according to the channel state.

4. Repeat the above steps.

The change of the channel state in step 1 can be from UP to DOWN, or from DOWN to UP.

The range of the preset time T in step 3 is: 1 minute≤T≤60 minutes.

In the above steps, the BFD mechanism may be used to detect the channel state, or other detection methods may be used.

When it is necessary to obtain the status of multiple channels, each channel can use the same timing length, and each channel can also set a timer separately. The timing time of each timer can be set separately according to the actual situation, so as to meet the needs of different channels for the length of response time. Different requirements, improve the practicability of channel state detection.

As shown in FIG. 2 , the first router A, the second router B, the third router C and the fourth router D form a first link A→B→C→D. The asynchronous mode is used for detection between the first router A and the second router B. The current state of the channel between A and B is UP. The work process of the embodiment of the invention is as follows:

1. The first router A periodically sends BFD packets to the second router B, and the sending period is 1ms;

2. Within three periods, that is, within 3ms, the first router A does not receive the BFD message sent by the second router B, then it is judged that the channel between the first router A and the second router B changes from UP to DOWN;

3. Start the first timer to start timing;

4. Continue to detect the state of the channel between the first router A and the second router B until the time counted by the first timer is equal to the first preset time T1. In this embodiment, T1=2 minutes, during which BFD It is detected that the channel state has changed from UP to DOWN for many times, and then DOWN has changed to UP, but after 1 minute, the channel state is stable at UP state; at this time, because the state between the first router A and the second router B is relatively The original state has not changed and is all UP, so there is no need to notify the application, and the application does not know that the channel has been disconnected; of course, the channel status between the first router A and the second router B can also be notified to the application at this time. , the application discovery state is still UP, and the path from the first router A to the second router B in the first link remains unchanged.

If the WTR mechanism of the present invention is not used, the application will be notified every time the channel state is detected. When the channel between the first router A and the second router B changes from UP to DOWN initially, the application will reselect the channel from the first router A The path leading to the fourth router D, for example, is selected from A→E→C→D; and within T1 time, after the state of the channel between the first router A and the second router B changes to UP again, the application needs to be updated again The routing tables of the first router A, the second router B, and the third router C of the relevant routers are repeated many times, which will cause a great consumption of resources such as CPU memory and a waste of bandwidth.

Another embodiment of the present invention is described below in conjunction with Fig. 2, the current channel between the first router A and the fifth router E is DOWN, and the query mode is used for detection between the first router A and the fifth router E, the present embodiment The working process is as follows:

1. The first router A sends a BFD packet to the fifth router E;

2. Within 3ms, the first router A receives the BFD message returned by the fifth router E, then judges that the channel between the first router A and the fifth router E changes from DOWN to UP, and notifies the routing module of the UP status ;

3. The routing module starts the second timer to start timing;

4. Continue to detect the state of the channel between the first router A and the fifth router E until the time counted by the second timer is equal to the second preset time T2. In this embodiment, T2=30 minutes. During the period, pass BFD detects that the channel state between the first router A and the fifth router E has changed from UP to DOWN and then from DOWN to UP for many times, and notifies the routing module of all of them, but the routing module does not respond. After 10 minutes, the channel state is stable in the UP state; after 30 minutes, the routing module updates the first router A, the fifth router E, the second router B, the third router C and the sixth router according to the UP state of the current channel. F's routing table.

If the WTR mechanism of the present invention is not adopted, then the routing module responds whenever the information of the channel state is obtained, and when the channel between the first router A and the fifth router E changes from DOWN to UP at first, it is necessary to update the relevant router No. The routing tables of Router A, Router E, Router B, Router C and Router F, because the network is unstable, the channel between Router A and Router E within 15 minutes If it changes to DOWN for many times, and then becomes UP again, the routing tables of the first router A, the fifth router E, the second router B, the third router C and the sixth router F must be updated multiple times, resulting in Great consumption of resources such as CPU memory and waste of bandwidth.

Claims (6)

1, a kind of method for obtaining communication system channel status, it is characterized in that, comprise the following steps: 1) detect the information that channel status changes; 2) start timer and start counting; 3) continue to detect channel status, until timing The time counted by the device is equal to the preset time T, and the current channel status is obtained. 2. The method for obtaining channel status of a communication system according to claim 1, characterized in that, after step 3), the method further includes the following step: notifying the corresponding application of the current status of the channel. 3. The method for obtaining channel status of a communication system according to claim 1, characterized in that, after the step 3), the following step is further included: the corresponding application responds according to the channel status. 4. The method for obtaining channel status of a communication system according to claim 1, wherein the channel status in step 1) changes from UP to DOWN or from DOWN to UP. 5. The method for obtaining channel status of a communication system according to claim 1, characterized in that the range of the preset time T in step 3) is: 1 minute≤T≤60 minutes. 6. The method for obtaining channel status of a communication system according to any one of claims 1 to 5, characterized in that: in the step 1) and step 3), a bidirectional forwarding detection (BFD) mechanism is used to detect the channel status.

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