Granted Patent B2

US 7,978,614 · App. 11/953,743 · Granted Jul 12, 2011

Abstract

Claims (27)

1. A method performed by a network device of detecting non-receipt of failure detection protocol packets, the method comprising:

storing, at the network device, timer information for each session in a plurality of failure detection protocol sessions, the timer information for each session comprising a first timer specifying a time value indicative of a periodic time interval for receiving a failure detection protocol packet for the session and a second timer specifying a time value indicative of an amount of time since a failure detection protocol packet was last received for the session;

determining, based upon the first timer values specified for the plurality of failure detection protocol sessions, a time period for comparing the timers for the plurality of failure detection protocol sessions;

based upon the determined time period, periodically comparing, for each session in the plurality of failure detection protocol sessions, the first timer value specified in the timer information for the session with the second timer value specified in the timer information for the session; and

determining, based upon the comparing for a first session in the plurality of failure detection protocol sessions, that a failure detection protocol packet for the session is not received by the network device within the periodic time interval specified by the timer information for the first session;

wherein determining the time period comprises setting the time period to a least common denominator of the first timer values specified for the plurality of failure detection protocol sessions;

wherein determining that a failure detection packet is not received is performed by a module of the network device other than a processor of the network device, the processor configured to execute software for processing failure detection protocol packets.

2. The method of claim 1 wherein determining that a failure detection protocol packet is not received for the first failure detection protocol session comprises:

indicating that a failure detection protocol packet is not received within the periodic time interval for the first session when the second timer value for the first session equals or exceeds the first timer value for the first session.

3. The method of claim 1 further comprising, for each session in the plurality of failure detection protocol sessions, resetting the second timer value for the session upon receiving a failure detection protocol packet for that session.

4. The method of claim 1 wherein the first timer value for each session in the plurality of failure detection protocol sessions is set by the software executed by the processor of the network device.

5. The method of claim 1 wherein the first failure detection protocol session is a Bidirectional Forwarding (BFD) protocol session.

6. The method of claim 1 wherein the first failure detection protocol session is an 802.1ag protocol session.

7. A system for detecting non-receipt of failure detection protocol packets, the system comprising:

a processor configured to execute software for processing failure detection protocol packets;

a memory configured to store timer information for each session in a plurality of failure detection protocol sessions, the timer information for each session comprising a first timer specifying a time value indicative of a periodic time interval for receiving a failure detection protocol packet for the session and a second timer specifying a time value indicative of an amount of time since a failure detection protocol packet was last received for the session; and

a module configured to:

determine, based upon the first timer values specified for the plurality of failure detection protocol sessions, a time period for comparing the timers for the plurality of failure detection protocol sessions;

based upon the determined time period, periodically compare, for each session in the plurality of failure detection protocol sessions, the first timer value specified in the timer information for the session with the second timer value specified in the timer information for the session; and

wherein the time period for the comparing is set to a least common denominator of the first timer values specified for the plurality of failure detection protocol sessions;

determine, based upon the comparison for a first session in the plurality of failure detection protocol sessions, that a failure detection protocol packet for the session is not received by the system within the periodic time interval specified by the timer information for the first session.

8. The system of claim 7 wherein the module is configured to indicate that a failure detection protocol packet is not received within the periodic time interval for the first session when the second timer value for the first session equals or exceeds the first timer value for the first session.

9. The system of claim 7 wherein the module is configured to, for each session in the plurality of failure detection protocol sessions, reset the second timer value for the session upon receiving a failure detection protocol packet for that session.

10. The system of claim 7 wherein the first timer value for each session in the plurality of failure detection protocol sessions is set by the software executed by the processor.

11. The system of claim 7 wherein the first failure detection protocol session is a Bidirectional Forwarding (BFD) protocol session.

12. The system of claim 7 wherein the first failure detection protocol session is an 802.1ag protocol session.

13. The system of claim 7 wherein the module is a field-programmable logic device.

Assignments (13)