Patent ID: 8213420

Claim:
A network stack comprising: a plurality of network units, wherein each of the plurality of network units comprises a multiplicity of ports for receiving and forwarding addressed data packets, at least two cascade ports, and a switching engine for forwarding received data packets to at least one of the multiplicity of ports in accordance with address data in the data packets; a first cascade connection comprising a first unidirectional path for data packets composed of links between a first cascade port of a first network unit and a cascade port of a second network unit, wherein the data packets are to flow through the first unidirectional path from the first cascade port of the first network unit to the cascade port of the second network unit; and a second cascade connection comprising a second unidirectional path for the data packets composed of links between a second cascade port of the first network unit and a cascade port of a third network unit, wherein the second unidirectional path is directed into a direction that is opposite the first unidirectional path, wherein the data packets are to flow through the second unidirectional path from the second cascade port of the first network unit to the cascade port of the third network unit, wherein each of the data packets which is received at any given port of a given network unit from an external network and is forwarded onto one of the first and the second cascade ports is provided a header source field which, uniquely across the plurality of network units, identifies the given port and the given network unit through which the data packet was received.