Routing methods, systems, and computer program products

What is this patent about?

’133 is related to the field of network routing and packet forwarding, specifically addressing the limitations of traditional Internet Protocol (IP) routing. In conventional IP networks, routing is typically based on a destination address where each intermediate node independently determines the next hop. This patent explores a shift toward path-based addressing, where the route or specific segments of a path are encoded directly within the packet to provide more granular control over the data's journey through the network.

The underlying idea behind ’133 is to embed explicit path information into the packet header itself, allowing the network to function more like a source-routed system. By utilizing segment identifiers (SIDs), the invention enables a node to steer a packet through a specific sequence of hops or network segments. This mechanism effectively collapses the distinction between a name, an address, and a route, allowing the packet to carry its own instructions for navigation rather than relying solely on the independent routing tables of every intermediate switch or router.

The claims of ’133 focus on a system and method where a node receives a packet with an IP header and modifies it by adding a first extension header. This extension header contains a list of elements, each representing a specific segment identifier. The node then updates the packet by writing one of these SIDs from the list directly into the destination IP address field of the IP header. This process ensures that the packet is directed to the specific network segment or node identified by the current SID in the sequence.

In practice, the invention operates by dynamically updating the destination field as the packet traverses the network. When a node receives an IPv6 packet, it inspects the segment routing (SR) header to determine if the current destination address matches a SID in the segment list. If a match is found, the node utilizes a specialized forwarding table to advance the packet. This allows for complex path steering where the destination address field acts as a pointer to the current active segment of the overall path.

This approach differs from prior solutions by eliminating the need for every node to maintain a global view of the network topology. Instead of traditional hop-by-hop lookups based on a static final destination, the invention uses nested protocol addresses and extension headers to provide a self-contained routing instruction set. By overwriting the destination field with the next SID in the list, the system repurposes standard IP header fields to support sophisticated source routing and traffic engineering without requiring a complete overhaul of existing IP infrastructure.