Enabling planned upgrade/downgrade of network devices without impacting network sessions

A system for enabling a planned change of a first network device during a TCP session, the first network device configured to:

• establish a TCP session with a client device;
• receive a request for a virtual service over a network by the client device;
• deliver the request for the virtual service over a network to a server;
• receive a change from a network administrator designating the second network device as the active device for the service;
• receive a redirected server response from the second network device;
• and
• send the redirected server response to the client device.

A non-transitory processor-readable medium having instructions stored thereon, which when executed by one or more processors, cause the one or more processors to perform the following operations:

• establishing at the first network device, a TCP session with a client device;
• receiving, at the first network device, a request for a virtual service over a network by the client device;
• creating a redirect network session for the TCP session at a second network device, the second network device being a standby device;
• delivering, by the first network device, the request for the virtual service over a network to a server;
• receiving a change from a network administrator designating the second network device as the active device for the service;
• receiving a server response at the second network device;
• recognizing, at the second network device, that the server response is associated with the redirect network session;
• redirecting the server response to the first network device in accordance with the redirect network session;
• and
• sending, by the first network device, the server response to the client device.