Backup service managers for providing reliable network services in a distributed environment

A fault tolerant method of providing a network service including:

• receiving a first criteria specifying a first set of flows from a first service manager at a forwarding agent wherein the first criteria specifies an expiration time interval;
• storing the first criteria on the forwarding agent;
• receiving a second criteria specifying a second set of flows from a second service manager at the forwarding agent wherein the second set of flows includes flows that are in the first set of flows and wherein the second criteria is designated as a lower priority criteria;
• storing the second criteria on the forwarding agent;
• deleting the first criteria from the forwarding agent upon the expiration of the expiration time interval;
• receiving a packet belonging to a flow that is included in the first set and the second set;
• determining that the packet matches the second set;
• and
• forwarding the packet to the second service manager.

A computer program product embodied in a computer readable medium for providing a network service in a fault tolerant manner comprising computer instructions for:

• sending a first criteria specifying a first set of flows from a first service manager to a forwarding agent;
• storing the first criteria on the forwarding agent;
• sending a second criteria specifying a second set of flows from a second service manager to the forwarding agent wherein the second set of flows includes flows that are in the first set of flows and wherein the second criteria is designated as a lower priority criteria;
• storing the second criteria on the forwarding agent;
• receiving a packet belonging to a flow that is included in the first set and the second set;
• determining that the packet matches the first set;
• and
• forwarding the packet to the first service manager, wherein the second service manager is operable to function as a primary service manager or a backup service manager.

A computer program product embodied in a computer readable medium for providing a network service in a fault tolerant manner comprising computer instructions for:

• sending a first criteria specifying a first set of flows from a first service manager to a forwarding agent wherein the first criteria specifies an expiration time interval;
• storing the first criteria on the forwarding agent;
• sending a second criteria specifying a second set of flows from a second service manager to the forwarding agent wherein the second set of flows includes flows that are in the first set of flows and wherein the second criteria is designated as a lower priority criteria;
• storing the second criteria on the forwarding agent;
• deleting the first criteria from the forwarding agent upon the expiration of the expiration time interval;
• receiving a packet belonging to a flow that is included in the first set and the second set;
• determining that the packet matches the second set;
• and
• forwarding the packet to the second service manager, wherein the second service manager is operable to function as a primary service manager or a backup service manager.

A computer program product embodied in a computer readable medium for providing a network service according to instructions from a service manager comprising computer instructions for:

• receiving a first criteria specifying a first set of flows from a first service manager to wherein the first criteria specifies an expiration time interval and to receive a second criteria specifying a second set of flows from a second service manager wherein the second set of flows includes flows that are in the first set of flows and wherein the second criteria is designated as a lower priority criteria;
• storing the first criteria and the second criteria;
• and
• checking the stored first criteria and to delete the stored first criteria upon the expiration of the expiration time interval, wherein the second service manager is operable to function as a primary service manager or a backup service manager.