System and method for performing an in-service software upgrade in non-redundant systems

A method of performing an in-service software upgrade in a network device having a processor and a memory, comprising:

• maintaining, by the processor, an active image and a standby image, the active image having control of the network device;
• receiving, by the active image, a data value representing an entry in a routing or forwarding table, the entry comprising an address used for routing and forwarding data packets:
• providing, by the active image, the data value to the standby image;
• determining, by the active image, an index for the data value, the index being based on a position of the data value within a first routing or forwarding table maintained by the active image;
• calculating, by the active image, a first key as a function of only the data value;
• storing, by the active image, the data value, the index, and the first key in the first routing or forwarding table;
• calculating, by the standby image, a second key as a function of only the data value;
• receiving, by the active image, a request for the index and the data value from the standby image, the request including the second key;
• providing, by the active image in response to receiving the request from the standby image, the data value and the index to the standby image when the first key matches the second key;
• storing, by the standby image, the data value, the index, and the second key in the second routing or forwarding table;
• and
• switching control of the network device from the active image to the standby image when the active image becomes inactive.

An information handling system, comprising:

• one or more network devices coupled together to route information between the one or more network devices and other network devices coupled thereto based on routing information stored in the one or more network devices, wherein a first device of the one or more network devices comprises:
• a routing processor;
• one or more line cards coupled to the routing processor, the one or more line cards receiving the routing information from the routing processor for routing data packets to a destination;
• and
• a memory coupled to the routing processor, wherein the routing processor is configured to:
• maintain an active image and a standby image, the active image having control of the first device;
• receive, by the active image, a data value representing an entry in a routing or forwarding table, the entry comprising an address used for routing and forwarding data packets:
• provide, by the active image, the data value to the standby image;
• determine, by the active image, an index for the data value, the index being based on a position of the data value within a first routing or forwarding table maintained by the active image;
• calculate, by the active image, a first key as a function of only the data value;
• store, by the active image, the data value, the index, and the first key in the first routing or forwarding table;
• calculate, by the standby image, a second key as a function of only the data value;
• receive, by the active image, a request for the index and the data value from the standby image, the request including the second key;
• provide, by the active image in response to receiving the request from the standby image, the data value and the index to the standby image when the first key matches the second key;
• store, by the standby image, the data value, the index, and the second key in the second routing or forwarding table;
• and
• switch control of the first device from the active image to the standby image when the active image becomes inactive.