CN100586082C - A retrospective type route level network topology detecting method based on topology tree - Google Patents

Abstract

A topological test method of a retrospective routing network based on a topological tree belongs to the network topological test field; the current network topological test algorithm has high testing redundancy and low efficiency and cannot check the topological structure of large-scaled network immediately and precisely, and the method uses an aiming address which has reflections to the test in order to retrospectively test a network topological part, and analyzes the network topological characteristics before finding out an out-degree multiplied by the topological node with the largest path-length value from the out-degree to the tested source, and takes the path-length as a TTL value of a data base with an initial measurement to retrospectively test the part which the aiming address shows no reflection so as to efficiently complete the whole topological process. According to the test, the method only takes 18 percent of time used by the traditional topological test algorithm in finding 98 percent of network topological information, and is applied in the network topological test that has stricter requirements for the exploring time and topological discovery rate and is a quick and efficient routing network topological test method.

Description

Recall formula route level network topology detection method based on topological tree

Technical field

The present invention relates to a kind of quick topology detection method of large scale network, can improve the efficient detection time required that large-scale network topological detects effectively, belong to the network topology detection range with minimizing.

Background technology

At present, common route level network topology detection method is based on all that life span (TTL) restriction of network packet carries out, basic principle, be that at first to send ttl field from test point be that 1 packet is to destination address, after first router receives this packet in the network path from the test point to the destination address, beam back an ICMP " overtime " packet to detection resources, the interface IP address that comprises this router in this packet, to send ttl field be that 2 packet is to destination address to detection resources then, second router beamed back ICMP " overtime " packet to detection resources after receiving this packet in the network path, thereby obtain the interface IP address of second router, obtain all-router interface IP in the whole piece path from the detection resources to the destination address thereby move in circles.Right by detecting a large amount of detection resources and destination address, just can obtain the interface IP information of router in the whole network, further processing can obtain the route level topology of whole network.Owing to need detect every paths in the network, so the cross part branch in different paths is detected repeatedly in the network, particularly this redundancy is very high in large-scale network topology detects.In order to reduce redundancy, to improve detection efficiency and reduction topology detection time, some follow-on methods have appearred, first ttl value that detects packet is set to certain value greater than 1 according to different algorithms for they, thereby in certain probable range, reduce the redundancy that detects, but this probability is uncertain, in the network topology testing process, this improvement can reduce redundancy effectively in some local detection of whole topology, and some other then can only have less redundancy to reduce.

Summary of the invention

In order to overcome the uncertainty that initial ttl value is provided with in the existing route level topology detection method, further reduce the redundancy of pouncing on detection and improve detection efficiency, the present invention utilizes the destination address of in the destination address set detection being made response, obtain its packet that returns and analyze destination address and the distance of detection resources, thereby determine the ttl value of initial examination and measurement packet, after obtaining section subnetwork topology information, analyze, thereby instruct proceeding of subsequent detection work.

The technical solution adopted for the present invention to solve the technical problems is: 1) once survey at all destination addresses with the 255 life span TTL as network packet; All right 64 or 128 life span TTL as network packet;

2) when certain destination address has response, obtain the ttl field value of this response data packet;

3) ttl value of present various operating system acquiescence response data packet is set to 16,32,64,128 or 255, and the absolute value of difference that is a bit larger tham its value in the TTL of the above-mentioned response data packet that obtains and this five values is the path N of destination address and detection resources;

4) utilize the tree-shaped characteristic of topological diagram, begin to recall network topology, promptly use TTL=N-1, TTL=N-2, TTL=N-3 until the packet testing goal address of TTL=1, and note the router interface address that obtains from destination address; When detecting certain router interface that has been found that, the detection process of this destination address is ended, continue to survey next destination address;

Concentrating not the address that response is made in detection when destination address can be left in the basket, and the topology detection process serves as to detect the address to proceed with next destination address;

5) finish after the single pass to whole destination address collection, obtain the part of whole real network topology, analyze the topological diagram that obtains this moment, finds out that out-degree multiply by the topological node of path value maximum as optimum node in the topological diagram;

6) be that the ttl value of initial examination and measurement packet is recalled the address that does not have response in the testing goal address set with the path of above-mentioned optimum node, and record obtains topology, finish whole topology detection process.

The invention has the beneficial effects as follows, can reduce the redundancy that network topology detects effectively, reduce the topology detection time and improve Topology Discovery efficient, operate simultaneously and implement more convenient.

Description of drawings

Fig. 1 is original topology detection algorithm pattern.

Fig. 2 is the topology detection algorithm pattern after improving

Fig. 3 recalls formula topology detection algorithm pattern

Fig. 4 recalls the formula topology detection algorithm first run to survey the network topology that the back is found

Wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 represent router one-9

D (Destination) 1, D2, D3, D4, D5 represent destination address 1-5

M (Monitor) represents detection resources

Embodiment

In the embodiment shown in fig. 3, the destination address set is D1, D2, D3, D4 and D5, and M is a detection resources, and R1, R2, R3, R4, R5, R6, R7, R8 and R9 are 9 routers in the network topology.

1) once surveys at 5 destination addresses in the destination address collection with 255 life span TTL as network packet.

2) when certain destination address has response, obtain the ttl field value of response data packet.Wherein D1, D2 and D4 make response to detection, return corresponding response data packet.Obtain separately ttl value from three response data packet, be respectively TTL1=251, TTL2=124, TTL4=60.

3) ttl value of present various operating system acquiescence response data packet is set to 16,32,64,128 or 255, and the absolute value of difference that is a bit larger tham its value in the TTL of the above-mentioned response data packet that obtains and this five values is the path N of destination address and detection resources.Therefore the path of D1, D2 and D4 is respectively N1=255-251, N2=128-124, N4=64-60.

4) utilize the tree-shaped characteristic of topological diagram, begin to recall network topology, promptly use the packet testing goal address of TTL=N-1, TTL=N-2, TTL=N-3......., and note the router interface address that obtains from destination address; When detecting certain router interface that has been found that, the detection process of this destination address is ended, continue to survey next destination address.For D1, the set of routers I that have been found that this moment is for empty.Use the probe data packet of TTL=3, TTL=2, TTL=1 that it is surveyed then respectively, obtain the information of router R4, R3 and R1, therefore this moment I={R4, R3, R1}; For D2, use the packet of TTL=3, TTL=2, TTL=1 that it is surveyed respectively, successively obtain the information of router R8, R3, this moment is because R3 is in gathering I, i.e. detection runs into the router that has been found that, this moment, the detection to D2 stopped I={R4, R3, R1, R8}; For D4, use the packet of TTL=3, TTL=2, TTL=1 that it is surveyed respectively, successively obtain the information of router R6, R2, R1, this moment is because R1 is in gathering I, i.e. detection runs into the router that has been found that, this moment, the detection to D2 stopped I={R4, R3, R1, R8, R6, R2}.

5) destination address concentrates not the address that response is made in detection to be left in the basket, and the topology detection process serves as to detect the address to proceed with next destination address.Because D3 and D5 do not make response to detection resources M, therefore in first run detection process, be left in the basket.

6) after the single pass of finishing whole destination address collection, will obtain the part of whole real network topology, analyze the topological diagram obtain this moment, finds out that out-degree multiply by its topological node to the path value S maximum of detection resources in the topological diagram, as optimum node.After detecting and finish, the first run obtains the part of topology among Fig. 3, as shown in Figure 4.Obtained this moment router R4, R3, R1, R8, R6, R2 and between annexation.Be respectively S4=3x1 for this its S value of 6 routers, S3=2x2, S1=1x3, S8=3x1, S6=3x1, S2=1x1, so R3 is optimum node.

7) be that the ttl value of initial examination and measurement packet is recalled the address that does not have response in the testing goal address set with the path of optimum node, and record obtains topology, thereby finish whole topology detection process.Path with optimum node R 3 continues to survey destination address D3 and the D5 that does not have response.For D3, at first use the packet of TTL=2 that it is surveyed, obtain the information of router R5, use the packet of TTL=3, TTL=4....... that it is surveyed then, obtain the information of router R7, R9.Because R5 is in I, recall formula and survey so need to carry out, promptly recall D3 with the packet of TTL=1, obtain router R1 because R1 in I, surveys and ends, this moment I={R4, R3, R1, R8, R5, R7, R9}; For D5, at first use the packet of TTL=2 that it is surveyed, obtain the information of router R2 because R2 in I, does not need to carry out and do not recall formula and survey, therefore survey and end, this moment I={R4, R3, R1, R8, R5, R7, R9}.Whole topology detection process end has also been found whole network topologies.

All numerical value is specialized, step by step.

Effect comparison (available form)

The algorithm title	Survey required time	The Topology Discovery rate
			The original topology detection algorithm	100％	100％
Topology detection algorithm after the improvement	24％	90％
			Recall formula topology detection algorithm	18％	98％

Claims (2)

1, based on topological tree recall formula route level network topology detection method, it is characterized in that, may further comprise the steps:

1) once surveys at all destination addresses with 255 life span TTL as network packet;

2) when certain destination address has response, obtain the ttl field value of this response data packet;

3) ttl value of present various operating system acquiescence response data packet is set to 16,32,64,128 or 255, and the minimization of the sum of absolute value of difference of value greater than it in the TTL of the above-mentioned response data packet that obtains and this five values is the path N of destination address and detection resources;

4) use TTL=N-1, TTL=N-2, TTL=N-3 until the packet testing goal address of TTL=1, and note the router interface address that obtains; When detecting certain router interface that has been found that, the detection process of this destination address is ended, continue to survey next destination address;

Destination address concentrates not the address that response is made in detection to be left in the basket, and the topology detection process serves as to detect the address to proceed with next destination address;

5) finish after the single pass to whole destination address collection, obtain the part of whole real network topology, analyze the topological diagram that obtains this moment, finds out that out-degree multiply by the topological node of path value maximum as optimum node in the topological diagram;

6) be that the ttl value of initial examination and measurement packet is recalled the address that does not have response in the testing goal address set with the path of above-mentioned optimum node, and record obtains topology, finish whole topology detection process.

2, according to claim 1 based on topological tree recall formula route level network topology detection method, it is characterized in that,

Replace 255 life span TTL with 64 or 128 in the step 1) as network packet.

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