Patent ID: 9100236
Filing Date: 2015-08-04
Classification: H04L

Abstract:
1. A method comprising: sending, by an intermediate network device that is configured as a backup network device to a primary network device, packets that advertise a transmission control protocol (TCP) window size of zero bytes to a client device and a server device of an established network session after the primary network device receives a synchronization (SYN) packet from the client device, a SYN-ACK (acknowledgement) packet from the server device, and an ACK packet from the client device; after sending the packets, receiving, by the intermediate network device, a first zero-window probe packet from the client device, wherein the first zero-window probe packet includes data representing a first current sequence number for a client-to-server packet flow of the established network session, and a second zero-window probe packet from the server device, wherein the second zero-window probe packet includes data representing a second current sequence number for a server-to-client packet flow of the established network session; initializing a first TCP state for the client-to-server packet flow based on the first current sequence number and a second TCP state for the server-to-client packet flow based on the second current sequence number; and acting, by the intermediate network device, as a TCP proxy for packets following the first zero-window probe packet of the client-to-server packet flow based on the first TCP state and packets following the second zero-window probe packet of the server-to-client packet flow based on the second TCP state.