Patent ID: 7480292

Claim:
A method of processing IP packets at layer three level in a telecommunication equipment, the equipment comprising a first box containing layer 4 protocols, and a second box containing hardware interfaces and layer 2 drivers, the method comprising the following steps in the following order, which are performed by a first termination block: in the incoming direction: validating IP packets by performing checks, managing options field by interpreting all the options that said first termination block understands and preserving unaltered all other options, filtering, deciding first next layer and forwarding; in the outgoing direction: managing redirect by checking if the packet that is going to be sent satisfies the following conditions: the IP packet has been received from a same interface over which the IP packet is going out, the source address belongs to a sub-network of a next-hop, there is no source route option, managing TTL by considering a valid packet any IP packet addressed to the equipment and with TTL equal to zero, managing source address, managing options field by interpreting all the options that said first termination block understands and preserving unaltered all other options, fragmenting packets when the packet to be routed has a size greater than a Maximum Transmission Unit, wherein, in case of IP packets originated from or destined to the equipment, said method further comprising the following steps in the following order, which are performed by a second termination block in the incoming direction, after the first next layer decision and forwarding step: validating the IP packets by performing checks, reassembling incoming fragmented packets, managing options field by interpreting all options that said second termination block understands, deciding second next layer by stripping the header and forwarding the payload to the upper client layers using the protocol as selector; in the outgoing direction, before the step of managing redirect: multiplexing IP payloads coming from different upper layer protocols, managing options field, and generating IP headers.