Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network monitoring
Reexamination Certificate
1998-07-15
2001-01-09
Coleman, Eric (Department: 2783)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network monitoring
C714S053000
Reexamination Certificate
active
06173324
ABSTRACT:
TECHNICAL FIELD
This invention relates to a technique for proactively detecting and isolating connectivity troubles in high-speed data networks.
BACKGROUND ART
Present day data networks typically comprise routers or other types of switches that route customer data packets over one or more links (e.g., virtual circuits) between a data source (e.g., a customer's computer connected to the data network) and destination. Successful routing of customer data packets requires that a logical path (a collection of one or more links) exist in the network between the source and destination for that packet. Based on the contents of its routing table, each router along the path ascertains from the data packet it receives the identity of the downstream router (or data destination) to receive the packet. Assuming the network possesses sufficient physical redundancy (e.g., multiple routers, multiple links), the network can dynamically redefine paths using protocols such as the Border Gateway Protocol (BGP) or Open Shortest Path First (OSPF) protocol, in case of a router or link failure. The use of such protocols ensures that no one router or link failure disrupts the flow of packets between a data source and destination.
Numerous commercial monitoring systems presently exist for detecting the operating status of routers. However, such systems typically provide local monitoring of the routers themselves, focusing on whether the routers successfully responded to a connectivity test request. Because current data networks enjoy redundancy (i.e., multiple physical paths may potentially exist between any data source and destination), one or more router failures do not necessarily indicate a customer connectivity trouble. Such present day monitoring systems ignore a key requirement for customer connectivity, namely that a path must exist between a prescribed data source and data destination, as indicated by contents of each routing table. Typically, such prior art monitoring systems often falsely notified the network manager (i.e., the individual(s) responsible for network oversight) of a customer connectivity trouble, requiring the network manager probe the network further. Often, the network manager had to spend large amounts of time to determine the cause of the customer connectivity trouble. In the past, most network managers used a non-deterministic monitoring methodology to determine customer connectivity failures. Often, a customer would detect the trouble first before the network manager, usually leading to customer dissatisfaction.
Thus, there is need for a technique for detecting and isolating customer connectivity troubles.
BRIEF SUMMARY OF THE INVENTION
Briefly, the present invention provides a technique for detecting and isolating connectivity troubles in a data network that includes links extending between routers that collectively route traffic across the links between at least one data source and at least one data destination in accordance with routing information contained in the routing table in each router. In accordance with the invention, the routing table in each router is checked to determine if there are any missing routes. In other words, the routing tables are checked to determine whether collectively, a path exists across one or more routers between a prescribed data source and data destination. If no such path exists, then the network manager is notified to investigate and correct the problem. Upon detecting a missing route, a check is also made to determine whether the failure occurred as a result of a Border Gateway Protocol (BGP) failure or an Open Shortest Path First (OSPF) failure. Upon either type of failure the network manager is notified to undertake an investigation to determine and correct such a failure.
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AT&T Corp
Coleman Eric
Levy Robert D.
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