Network looping detecting apparatus

• US 8,125,895 B2
• Filed: 03/11/2005
• Issued: 02/28/2012
• Est. Priority Date: 07/14/2004
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yasuie, Takeshi, Nomura, Yuji
• Primary Examiner(s): Moe, Aung S
• Assistant Examiner(s): Alia, Curtis A
• Application Number:
  US11/077,908
• Publication Number:
  US 20060013143A1
• Time in Patent Office: 2,545 Days
• Field of Search: 370/216, 370/222, 370229-231, 370235-236, 370/238, 370/351, 370/254, 709223-226
• US Class Current: 370/229
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 45/18 Loop-free operations
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion

Abstract

A network looping detecting apparatus has an increased real-time operation capability for network looping detection and also has scalability. The network looping detecting apparatus has a count information acquiring unit for periodically acquiring count information which is counted up when the lifetime of a packet has elapsed, from a network device of a network to be monitored for network looping. The network looping detecting apparatus also has a looping detecting unit for detecting network looping from the count information. Specifically, the network looping detecting apparatus detects network looping based on the fact that when a packet loops due to network looping, the lifetime of the packet elapses, and the count information is counted up.

Claims

1. A network looping detecting apparatus for detecting network looping, the network looping detecting apparatus comprising:

a count information acquiring unit to acquire, once in each acquisition period, count information which is counted up when a lifetime of a packet has elapsed from each network device in a network to be monitored for network looping; and

a looping detecting unit to calculate, for each network device, a difference between count information acquired at each of two consecutive acquisition periods, to select a pair of network devices the calculated differences of which are equal to or greater than a first threshold, to calculate a correlation value between said pair of network devices in terms of said differences, and to detect network looping between said pair of network devices if the correlation value is greater than or equal to a second threshold.

2. The network looping detecting apparatus according to claim 1, further comprising:

a memory to store device adjacency information representing adjacency relationship between network devices;

wherein said looping detecting unit refers to said device adjacency information and determines whether said pair of network devices are connected adjacent to each other or not for detecting network looping.

3. The network looping detecting apparatus according to claim 1, wherein said looping detecting unit specifies said network devices involved in the network looping.

4. The network looping detecting apparatus according to claim 3, further comprising:

a packet capturing unit to capture a packet in the network looping involving said network devices and confirming the network looping from invariable and variable parts of said packet.

5. The network looping detecting apparatus according to claim 3, wherein said looping detecting unit acquires a routing table from the specified network device and confirms the network looping from said routing table.

6. The network looping detecting apparatus according to claim 1, wherein said count information acquiring unit selects one of a plurality of IP addresses assigned to said network device, and accesses the selected IP address to acquire said count information.

7. The network looping detecting apparatus according to claim 1, wherein said count information comprises icmpOutTimeExcds in MIB.

8. A method of detecting network looping, the method comprising:

acquiring, once in each acquisition period, count information which is counted up when a lifetime of a packet has elapsed from each network device in a network to be monitored for network looping;

calculating, for each network device, a difference between said count information acquired at each of two consecutive acquisition periods;

selecting a pair of network devices whose calculated differences are equal to or greater than a first threshold;

calculating a correlation value between said pair of network devices in terms of said differences; and

detecting network looping between said pair of network devices if the correlation value is greater than or equal to a second threshold.