Reducing link state protocol traffic during graceful restart

A routing device comprising:

• a network interface communicatively coupled to a remote routing device of via a link on which a flood reduction technique is used;
• and
• one or more hardware-based processors configured to:
• receive, via the network interface, a first set of data from the remote routing device indicative of a first link state for the remote routing device according to a link-state protocol, wherein the first set of data is associated with a first sequence number and with a first checksum,
• store data representative of the first link state and the first sequence number,
• after receiving the first set of data, receive, via the network interface, a second set of data from the remote routing device indicating that the remote routing device will be performing a graceful restart,
• after receiving the second set of data, receive, via the network interface, a third set of data from the remote routing device representative of a second link state for the remote routing device, wherein the third set of data is associated with a second sequence number that is different than the first sequence number, and wherein the third set of data is associated with a second checksum,
• in response to the second set of data and the third set of data, determine whether the second link state is different than the first link state despite the difference between the first sequence number and the second sequence number, wherein to determine whether the second link state is the same as the first link state, the one or more hardware-based processors are further configured to calculate a third checksum using the stored first link state after replacing the first sequence number with the second sequence number, and
• avoid sending a request for a current link state to the remote routing device when the second link state is determined to be the same as the first link state despite the difference between the first sequence number and the second sequence number, wherein the one or more processors are configured to avoid sending the request when the third checksum is the same as the second checksum.

A system comprising:

• a first routing device;
• and
• a second routing device communicatively coupled to the first routing device via a link on which a flood reduction technique is used,
• wherein the second routing device is configured to send a first set of data to the first routing device indicative of a first link state for the second routing device according to a link-state protocol, wherein the first set of data is associated with a first sequence number and with a first checksum, send a second set of data to the first routing device indicating that the second routing device will be performing a graceful restart, and after performing the graceful restart, to send a third set of data to the first routing device representative of a second link state for the second routing device following the graceful restart, wherein the third set of data is associated with a second sequence number that is different than the first sequence number, and wherein the third set of data is associated with a second checksum, and
• wherein the first routing device is configured to store the first set of data and, in response to receiving the second set of data and the third set of data, determine whether the second link state is different than the first link state despite the difference between the first sequence number and the second sequence number, wherein to determine whether the second link state is different than the first link state, the first routing device is configured to calculate a third checksum using the stored first link state after replacing the first sequence number with the second sequence number, and wherein the first routing device is configured to avoid sending a request for a current link state to the second routing device when the second link state is determined to be the same as the first link state despite the difference between the first sequence number and the second sequence number, wherein the first routing device is configured to avoid sending the request for the current link state when the third checksum is the same as the second checksum.

A computer-readable storage medium comprising instructions that, when executed, cause a processor of a routing device, communicatively coupled to a remote routing device via a link on which a flood reduction technique is used, to:

• receive a first set of data from the remote routing device indicative of a first link state for the remote routing device according to a link-state protocol, wherein the first set of data is associated with a first sequence number and with a first checksum;
• store data representative of the first link state and the first sequence number;
• after receiving the first set of data, receive a second set of data from the remote routing device indicating that the remote routing device will be performing a graceful restart;
• after receiving the second set of data, receive a third set of data from the remote routing device representative of a second link state for the remote routing device, wherein the third set of data is associated with a second sequence number that is different than the first sequence number, and wherein the third set of data is associated with a second checksum;
• in response to the second set of data and the third set of data, determine whether the second link state is different than the first link state despite the difference between the first sequence number and the second sequence number, wherein the instructions that cause the processor to determine whether the second link state is the same as the first link state comprise instructions that cause the processor to calculate a third checksum using the stored first link state after replacing the first sequence number with the second sequence number;
• and
• avoid sending a request for a current link state to the remote routing device when the second link state is determined to be the same as the first link state despite the difference between the first sequence number and the second sequence number, wherein the instructions that cause the processor to avoid sending the request for the current link state comprise instructions that cause the processor to avoid sending the request when the third checksum is the same as the second checksum.

A method comprising:

• receiving, by a first routing device that is communicatively coupled to a second routing device via a link on which a flood reduction technique is used, a first set of data from the second routing device indicative of a first link state for the second routing device according to a link-state protocol, wherein the first set of data is associated with a first sequence number;
• storing, by the first routing device, data representative of the first link state and the first sequence number;
• after receiving the first set of data, receiving, by the first routing device, a second set of data from the second routing device indicating that the second routing device will be performing a graceful restart;
• after receiving the second set of data, receiving, by the first routing device, a third set of data from the second routing device representative of a second link state for the second routing device, wherein the third set of data is associated with a second sequence number that is different than the first sequence number;
• in response to the second set of data and the third set of data, determining, by the first routing device, whether the second link state is the same as the first link state despite the difference between the first sequence number and the second sequence number, wherein determining whether the second link state is the same as the first link state comprises determining whether the second link state is the same as the first link state despite the difference between the first sequence number and the second sequence number and despite any difference between a first age for the first link state and a second age for the second link state;
• and
• avoiding, by the first routing device, sending a request for a current link state to the second routing device when the second link state is determined to be the same as the first link state despite the difference between the first sequence number and the second sequence number.