Method, device, and system for deferring switchback

A method for deferring a switchback, comprising:

• receiving, by a second network device, a query packet from a first network device responsive to restoring a connection with the first network device, wherein the second network device is a primary network device;
• detecting, by the second network device responsive to receiving the query packet, whether a route from the second network device to a destination device is available to enable the first network device to defer switchback from a secondary route to a primary route until the primary route is available,
• wherein the second network device is a primary network device on the primary route from the first network device to the destination device,
• wherein a third network device is a secondary network device on the secondary route from the first network device to the destination device,
• wherein the second network device is a next hop on the primary route and the third network device is a next hop on the secondary route, and
• wherein the first network device switches to the secondary route to the destination device using the third network device instead of the second network device responsive to a failure of the second network device;
• and
• sending, by the second network device, a query response packet to the first network device when the route from the second network device to the destination device is available, wherein the query response packet indicates availability of the route between the second network device and the destination device, and wherein the query response packet is configured to trigger the first network device to switch back from the secondary route to the primary route.

A first network device for deferring a switchback, comprising:

• a processor;
• a transmitter coupled to the processor and configured to send, responsive to restoring a connection to a second network device, a query packet to the second network device to trigger the second network device to detect whether a route between the second network device to a destination device is available to enable the first network device to defer switchback from a secondary route to a primary route until the primary route is available,
• wherein the second network device is a primary network device on the primary route from the first network device to the destination device,
• wherein a third network device is a secondary network device on the secondary route from the first network device to the destination device,
• wherein the second network device k a next hop on the primary route and the third network device is a next hop on the secondary route, and
• wherein the first network device switches to the secondary route to the destination device using the third network device instead of the second network device responsive to a failure of the second network device;
• a receiver coupled to the processor and configured to:
• receive a query response packet from the second network device;
• and
• send the query response packet to the processor,
• wherein the processor is configured to:
• generate the query packet;
• send the query packet to the transmitter;
• and
• switch back from the secondary route to the primary route after the receiver receives the query response packet from the second network device, wherein the query response packet indicates availability of the route between the second network device and the destination device.

A second network device for deferring a switchback, comprising:

• a processor;
• a receiver coupled to the processor and configured to:
• receive a query packet from a first network device responsive to restoring a connection with the first network device;
• and
• send the query packet to the processor, wherein the second network device is a primary network device,
• wherein the processor is configured to detect, responsive to receiving the query packet, whether a route from the second network device to a destination device is available to enable the first network device to defer switchback from a secondary route to a primary route until the primary route is available,
• wherein the second network device is a primary network device on the primary route from the first network device to the destination device,
• wherein a third network device is a secondary network device on the secondary route from the first network device to the destination device,
• wherein the second network device is a next hop on the primary route and the third network device is a next hop on the secondary route, and
• wherein the first network device switches to the secondary route to the destination device using the third network device instead of the second network device responsive to a failure of the second network device;
• and
• a transmitter coupled to the processor and configured to send a query response packet to the first network device when the route from the second network device to the destination device is available, wherein the query response packet indicates availability of the route between the second network device and the destination device, and wherein the query response packet is configured to trigger the first network device to switch back from the secondary route to the primary route.

A second network device for deferring a switchback, wherein the second network device comprises:

• a transceiver configured to receive and send data information for establishing a primary route from a first network device to a destination device;
• a processor coupled to the transceiver and configured to:
• obtain association information, wherein the association information comprises an Internet Protocol (IP) address of a destination device and an identity of the first network device,
• wherein the association information indicates that the second network device is a next-hop device of the primary route from the first network device,
• wherein a destination address of the primary route is the IP address of the destination device,
• wherein the second network device is a primary network device on the primary route,
• wherein a third network device is a secondary network device on a secondary route from the first network device to the destination device,
• wherein the third network device is a next ho on the secondary route, and
• wherein the first network device switches to the secondary route to the destination device using the third network device instead of the second network device responsive to a failure of the second network device;
• obtain a restored Address Resolution Protocol (ARP) table;
• query the restored ARP table;
• obtain the IP address of the destination device in an ARP entry, wherein the IP address of the destination device identifies the destination device;
• query whether a route to the destination device is available;
• obtain, from the association information, the identity of the first network device corresponding to the IP address of the destination device when the route from the second network device to the destination device is available;
• establish, via the transceiver, a primary route to the first network device;
• and
• transmit a message, via the transceiver, to trigger the first network device to switch back from the secondary route to the primary route, and wherein the message indicates availability of the primary route between the second network device and the destination device.