Method and system for service function chaining

A network switch, comprising:

• network interfaces configured to receive and transmit packets of a network flow,
• network service function interfaces configured to communicate with one or more attached or connected network service functions, and
• a processing circuitry in communication with the network interfaces and the network service function interfaces, the service chain processing circuitry configured to:
• read, from a chain establishment packet that is received via a network interface of the network interfaces, network identifier information about network service functions of a chain of network service functions selected for the network flow, and
• perform, based on the network identifier information about the selected network service functions contained in the chain establishment packet, installation of packet forwarding rules for the flow together with network address and port translation operations.

A network addressable apparatus hosting a network service function, the apparatus comprising:

• a hardware component on which the network service function is executed,
• an operating system configured to manage the hardware component and a pool of port numbers, and
• a network function program running on the operating system that is configured to provide the network function's operations, wherein the network function program is configured:
• to query the operating system to provide a socket for a new network flow, and
• to receive and employ a socket for the new network flow that is provided with a port number selected by a delegated switch to which the network service function is attached are connected, instead of using a port number selected autonomously by the operating system.