RU2281612C2 - Method for data acquisition on network topology - Google Patents

Abstract

FIELD: network control; data acquisition on network topology.

SUBSTANCE: message requesting data acquisition on network topology that incorporates field limiting number of operations for message transfer from local station to adjacent ones is sent and following steps are repeated: request message receiving station returns response message and network topology data acquisition device finds out if number of message transfer operations has reached certain threshold value and terminates process if it is so, otherwise it sends request message to all adjacent stations.

EFFECT: facilitated procedure, reduced number of control errors.

7 cl, 2 dwg

Description

DESCRIPTION

Field of Invention

The present invention relates to network management, in particular, to a method for collecting network topology information.

State of the art

The collection of topology information is the basis for managing network trunks, and it requires that devices within the area of topology information collection retain information from adjacent devices. The process of collecting information about the topology is as follows: collecting information related to adjacent devices of all devices supporting the collection of information about the topology, in the area for collecting information about the topology is sent to the device that initiates the collection of information about the topology.

The methods of the prior art can be classified into methods of collecting information about the topology of two levels (L2) and methods of collecting information about the topology of three levels (L3). According to the L2 topology information collection, all topology information collection messages are transmitted via the L2 protocol, however, the L2 protocol alone does not provide a network routing function; as a result, all existing methods collect topology information based on a tree-like network, that is, by sending topology reports to the root node (in the direction of the reverse link), they summarize the topology information of the entire network in the root node. Such methods for collecting topology information are not applicable to other types of topology, for example, a trellised topology that is different from the tree structure.

The collection of information about the topology of the third level mainly refers to the collection of information about the topology based on the IP protocol (Internet protocol). All topology report messages are sent to the device, which initiates the collection of topology information using the standard routing protocol at the network level and forms the topology of the entire network. However, such methods of collecting topology information lead to complex routing algorithms at each node in the entire coverage area of the topology, which are impossible for lower-end products without the possibility of a router.

In addition, the existing technology for collecting topology information cannot guarantee the completeness of the collected topology information and therefore is usually compensated by periodically updating the topology so that collecting topology information does not affect the network for a long time, even if it is unsuccessful. However, for managing network devices, the immediate consequence of the incomplete collection of topology information is as follows: the network manager is not able to detect multiple network devices, leading to control errors.

In addition, to solve the cyclic problem in collecting information about the topology, the existing topology uses a "spanning" tree algorithm in a tree structure; however, since the spanning tree algorithm must be executed on each network device in the coverage area of the topology, the process of collecting information about the topology becomes more complicated.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an easy way to collect complete network topology information.

To solve the aforementioned problem, the network topology information collecting method according to the present invention comprises the following steps: the topology information collecting device sends a topology information collection request message containing a field limiting the number of message forwarding operations from the local node to adjacent nodes according to information of adjacent nodes, and then repeats the following steps:

a node that receives said request message returns a response message containing local node information and connection information to its adjacent nodes to said topology information collecting device;

determines if the number of message forwarding operations has reached a certain threshold value, if so, then ends the process, otherwise proceeds to the next step:

a node that receives the request message forwards sends the request message to all adjacent nodes.

When using the above method in a given topology information collection area, each device in the network can receive topology information collection request messages and respond to the topology collection device; The request message contains information about this device and information about connections to adjacent devices. Therefore, the device for collecting topology information can receive information from all devices and information about the relationship between them to achieve collection of information about the network topology, so that the network administrator can build a diagram (scheme) of the network topology that will serve as the basis for managing the backbone.

Brief Description of the Drawings

Figure 1 depicts the General sequence of operations of the method according to the present invention,

figure 2 shows the application of the present invention.

Detailed Description of Preferred Embodiments

The method according to the invention is illustrated by a description of specific variants of its implementation with reference to the accompanying drawings.

As shown in FIG. 1, the topology information collection device sends a topology information collection request message containing a field limiting the number of message forwarding operations from the local node to adjacent nodes according to information of adjacent nodes, and then repeats the following steps.

A node that receives said request message sends a response message containing local node information and connection information to its adjacent nodes to said topology information collecting device;

determines if the number of message forwarding operations has reached a certain threshold value; if so, it ends the process; otherwise, it proceeds to the next step.

A node that receives said request message forwards the said request message to all nodes adjacent to it. The field limiting the number of message forwarding operations is constructed in such a way as to control the area for collecting topology information, and it can be an integer; after the initial value is set, when the request message is sent, each device reduces the field value by 1; when the value reaches 0, the request message is no longer forwarded.

Said request message contains an initial route field that is used to record the sequence of sending messages; said response message comprises a response route field that is used to select a sequence for sending messages; whenever a request message is sent, the device identifier of this node is recorded in the source route field; the value of said response route field is obtained from said source route field by a reverse operation. A route refers to a series of identifiers for all devices in a sequence. Before forwarding the request message to its adjacent devices, the device adds its own device identifier to the end of the field of the original route of the request message; when the device responds to the received request message, it reverses the contents of the field of the original route of the request message as the route of the response message. In the embodiment of FIG. 2, when device A sends a topology request message 1 to device B, the original message route field contains only one device identifier, that is, A. Before sending the request message to its adjacent devices, device B adds its own identifier devices at the end of the initial route field of the request message; therefore, the field of the original route of message 2 or 3 of the request is A and B; when the device responds to the received request message, it inverts the sequence of the contents of the initial route field of the request message in the form of a response route field, that is, the response route field of the response message 4 or 5 of the device D or E is B and A.

To further prevent looped message forwarding when the device receives a topology information collection request message, if its source route field already contains the device identifier of this device, the request message will be rejected. If the destination address of the request message, that is, the last address in the source route field, is not the address of this device, then the device will forward the request messages to its adjacent devices according to the route indication.

During the distribution of topology request messages on the network, the device can receive request messages sent from multiple adjacent devices. To prevent the device from sending response messages again, said request message contains a topology information collection identifier field, the value of which is generated by the topology information collection device when it initiates a topology information collection request; whenever the collection process ends, the value of said field is increased by one and then serves as an identifier for collecting topology information for the next collection process; said response message comprises a topology information collection identifier field, the value of which is selected from the topology information collection identifier field of the corresponding request message; whenever a request message is received, the device compares the topology information collection identifier with that in the previous request message; if they are identical, the device rejects the request message; otherwise, it processes the request message.

While sending topology request messages to the network, a large number of network devices can receive topology request messages and send request messages at the same time, which can lead to network congestion and a busy topology information collection device. To avoid these problems, each device can wait a period of time before sending a topology request message. In an embodiment, it is assumed that the time interval from sending the request message to forwarding the request messages is T1; a request message is forwarded from port to port in a sequence identical to sending a response message to adjacent nodes. For example, suppose T1 = (x + Δ) ms, here x is the set value, Δ is a random number, the topology information collection request message mentioned contains the maximum Δ value and the time interval between operations of sending request messages from port to port. In an embodiment, x may be set to 200 ms, and said time interval may be set to 20 ms.

In order to further guarantee the completeness of topology information collection, whenever the topology information collection device receives a response message, it records a node that returns a message, marks the node as a passed node, and marks nodes that are adjacent to said node and did not respond, as expected nodes; then, the topology information collection apparatus will wait for a period of time and then perform a predetermined topology information collection operation for the expected nodes. If the device for collecting topology information does not detect a response message from some device, then it will collect information about the topology of the said device by means of a given operation of collecting information about the topology. In this case, since the topology information collection device already knows the route to the device according to the obtained relationship between the devices, it can perform addressing of the original route instead of the aforementioned level broadcasting, so as to reduce network congestion and increase information collection efficiency.

Claims (7)

1. A method for collecting network topology information in which a topology information collecting device sends a topology information collection request message from a local node to adjacent nodes according to information of adjacent nodes, said request message contains a field limiting the number of message forwarding operations, and then repeats the following steps: a node that receives said request message returns a response message containing local node information and connection information to its adjacent nodes to said devices gather information about the topology; determines if the number of message forwarding operations has reached a certain threshold value, if so, then terminates the process, otherwise proceeds to the next step: the node that receives the request message forwards the said request message to all nodes adjacent to it. 2. A method for collecting information about a network topology according to claim 1, wherein said request message comprises an initial route field that is used to record a message sending sequence; said response message comprises a response route field that is used to select a sequence for sending messages; whenever a request message is sent, the device identifier of this node is recorded in the source route field; the value of said response route field is obtained from said source route field by a reverse operation. 3. The method of collecting information about the network topology according to claim 2, in which, when the device receives a request message for collecting information about the topology, if the source route field already contains the device identifier of this device, it will reject the request message. 4. The method for collecting information about a network topology according to claim 1 or 2, wherein said request message comprises a field for identifying a topology information collection, the value of which is generated by the topology information collecting device when it initiates a topology information collecting request, each time when the collection process ends, the value of said field increases by one and then serves as an identifier for collecting topology information for the next collection process; said response message comprises a topology information collection identifier field, the value of which is obtained from the topology information collection identifier field of the corresponding request message whenever the request message is received, the device compares the topology information collection identifier with that in the previous request message; if they are identical, the device rejects the request message; otherwise, it processes the request message. 5. The method of collecting information about the network topology according to claim 2 or 3, in which it is assumed that the time interval from sending the request message to sending the request messages is T1; a request message is sent from port to port in a sequence identical to sending a response message to adjacent nodes. 6. The method of collecting information about the network topology according to claim 5, in which the time T1 = (x + Δ) ms, where x is the set value, Δ is a random number; said topology information collection request message contains a maximum Δ value and a time interval between operations of sending request messages from port to port. 7. The method for collecting information about the network topology according to claim 1, in which whenever the device for collecting topology information receives a response message, it records a node that returns a message, marks the node as a passed node, and marks nodes that are adjacent to mentioned node and did not respond as expected nodes; then, the topology information collection apparatus waits for a period of time, and then performs a predetermined operation of collecting topology information for the expected nodes.

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