Intermittent component failure manager and method for minimizing disruption of distributed computer system

Claim 2

In a distributed computer system having components which may fail intermittently, an intermittent failure filter comprising: status detection means, coupled to one of said components which may fail intermittently, which detects whether said component is working and transmits "working" and "broken" signals in accordance with said component's status; and a status filter, coupled to said status detection means, which receives said "working" and "broken" signals from said status detection means, retransmits without delay "broken" signals received after receiving a "working" signal, and retransmits received "working" signals only after a recovery time interval corresponding with a computed skepticism level during which no "broken" signals are received; wherein said status filter increases said computed skepticism level each time that a "broken" signal is received after said status filter has retransmitted a "working" signal.

Claim 3

The intermittent failure filter of claim 1, wherein said status filter decreases said computed skepticism level and redetermines said recovery time interval when, after said status filter has retransmitted a "working" signal, said status filter does not receive a "broken" signal for a second defined interval of time.

Claim 4

In a distributed computer system having components which may fail intermittently, an intermittent failure filter comprising: status detection means, coupled to one of said components which may fail intermittently, which detects whether said components is working and transmits "working" and "broken" signals in accordance with said component's status; and a status filter, coupled to said status detection means, having first, second and thirds states, which receives said "working" and "broken" signals and responds by moving to a corresponding state and selectively transmitting filtered "working" and "broken" signals to said computer system; wherein said status filter responds to receiving a "broken" signal, when in said second and third states, by moving to said first state and retransmitting said "broken" signal; said status filter responding to receiving a "working" signal when in said first state by moving to said second state and starting a wait timer with duration corresponding with a computed skepticism level; said status filter responding to expiration of said wait timer by moving to said third state and retransmitting said "working" signal; said status filter responding to "broken" signals received which in said second state by stopping said wait timer and returning to said first state; said status filter responding to receiving a "broken" signal, when in said third state, by retransmitting said "broken" signal, increasing said computed skepticism level, and moving to said first state.

Claim 5

In a distributed computer system having components which may fail intermittently, an intermittent failure filter comprising: status detection means, coupled to one of said components which may fail intermittently, which detects whether said components is working and transmits "working" and "broken" signals in accordance with said component's status; and a status filter, coupled to said status detection means, having first, second and thirds states, which receives said "working" and "broken" signals and responds by moving to a corresponding state and selectively transmitting filtered "working" and "broken" signals to said computer system; wherein said status filter responds to receiving a "broken" signal, when in said second and third states, by moving to said first state and retransmitting said "broken" signal; said status filter responding to receiving a "working" signal when in said first state by moving to said second state and starting a wait timer with duration corresponding with a computed skepticism level; said status filter responding to expiration of said wait timer by moving to said third state and retransmitting said "working" signal; said status filter responding to "broken" signals received which in said second state by stopping said wait timer and returning to said first state; said status filter responding to receiving a "broken" signal, when in said third state, by retransmitting said "broken" signal, increasing said computed skepticism level, and moving to said first state.

Claim 6

The intermittent failure filter of claim 3, wherein said status filter decreases said computed skepticism level, when in said third state after said status filter has retransmitted a "working" signal and said status filter does not receive a "broken" signal for a defined interval of time.

Claim 7

A mesh connected local area network for interconnecting a multiplicity of hosts, said network comprising: a multiplicity of switch means for simultaneously routing a multiplicity of data packets between hosts in the network; said hosts and switch means together comprising network members; a multiplicity of point to point link means for interconnecting said switch means and the hosts in said network, each point to point link means providing a communication channel between two of said network members; said multiplicity of link means including spanning tree links and a multiplicity of additional links; said multiplicity of switch means and said spanning tree links together comprising a spanning tree in which one of said switch means is designated the root of said spanning tree; each switch means including reconfiguration means for determining the position of said switch means in said spanning tree, said reconfiguration means including: configuration change detection means for detecting a change in the configuration of said network, including means for detecting the existence of a new connection between said switch means and another one of said network members and for detecting the breaking of a connection between said switch means and another one of said network members; a status filter, coupled to said configuration change detection means, which transmits a configuration change signal without delay whenever said configuration change detection means detects the breaking of a connection between said switch means and another one of said network members; said status filter responding to said configuration change detection means detecting the existence of a new connection between said switch means and another one of said network members by transmitting a configuration change signal only after a recovery time interval corresponding with a computed skepticism level during which said new connection does not fail; wherein said status filter increases said computed skepticism level each time that a new connection fails after said status filter has retransmitted a configuration change signal in response to said new connection being detected; and reconfiguration initiation means, coupled to said status filter, for responding to configuration change signals by initiating reconfiguration of said network; whereby disruption of said network by an intermittently operative connection is limited.

Claim 8

A mesh connected local area network for interconnecting a multiplicity of hosts, said network comprising: a multiplicity of switch means for simultaneously routing a multiplicity of data packets between hosts in the network; said hosts and switch means together comprising network members; a multiplicity of point to point link means for interconnecting said switch means and the hosts in said network, each point to point link means providing a communication channel between two of said network members; said multiplicity of link means including spanning tree links and a multiplicity of additional links; said multiplicity of switch means and said spanning tree links together comprising a spanning tree in which one of said switch means is designated the root of said spanning tree; each switch means including reconfiguration means for determining the position of said switch means in said spanning tree, said reconfiguration means including: configuration change detection means for detecting a change in the configuration of said network, including means for detecting the existence of a new connection between said switch means and another one of said network members and for detecting the breaking of a connection between said switch means and another one of said network members; a status filter, coupled to said configuration change detection means, which transmits a configuration change signal without delay whenever said configuration change detection means detects the breaking of a connection between said switch means and another one of said network members; said status filter responding to said configuration change detection means detecting the existence of a new connection between said switch means and another one of said network members by transmitting a configuration change signal only after a recovery time interval corresponding with a computed skepticism level during which said new connection does not fail; wherein said status filter increases said computed skepticism level each time that a new connection fails after said status filter has retransmitted a configuration change signal in response to said new connection being detected; and reconfiguration initiation means, coupled to said status filter, for responding to configuration change signals by initiating reconfiguration of said network; whereby disruption of said network by an intermittently operative connection is limited.

Claim 9

The mesh connected local area network of claim 5, wherein said status filter decreases said computed skepticism level and redetermines said recovery time interval when, after said status filter has transmitted a configuration change signal, said new connection does not fail for at least a defined interval of time.

Claim 10

In a distributed computer system having components which may fail intermittently, a method of limiting interruption by intermittent component failures comprising: determining whether a component is working and transmitting "working" and "broken" signals in accordance with said component's status; retransmitting received "working" signals only after a recovery time interval corresponding with a computed skepticism level during which no "broken" signals are received; retransmitting without delay "broken" signals received after retransmitting a "working" signal; and increasing said computed skepticism level, and redetermining said recovery time interval in accordance therewith, each time that a "broken" signal is received after a "working" signal has been retransmitted.

Claim 11

In a distributed computer system having components which may fail intermittently, a method of limiting interruption by intermittent component failures comprising: determining whether a component is working and transmitting "working" and "broken" signals in accordance with said component's status; retransmitting received "working" signals only after a recovery time interval corresponding with a computed skepticism level during which no "broken" signals are received; retransmitting without delay "broken" signals received after retransmitting a "working" signal; and increasing said computed skepticism level, and redetermining said recovery time interval in accordance therewith, each time that a "broken" signal is received after a "working" signal has been retransmitted.

Claim 12

The intermittent failure filter of claim 1, decreasing said computed skepticism level and redetermining said recovery time interval in accordance therewith when, after a "working" signal has been retransmitted, a "broken" signal is not received for at least a second defined interval of time.