Session-based forwarding

A network device having a symmetric multiprocessing architecture, the network device comprising:

• a plurality of CPU cores;
• a network interface to receive one or more data packets;
• and
• a memory whose access is shared by the dedicated CPU core and the plurality of CPU cores;
• wherein the plurality of CPU cores are to:
• receive a first packet in a session;
• perform a route lookup based on a header of the first packet to determine a route for the first packet;
• and
• cache a reference to the route and a neighbor in the session such that subsequent packets in the session are routed based on the cached reference in lieu of subsequent route lookups.

A non-transitory computer-readable storage medium storing embedded instructions for a plurality of operations that are executed by one or more mechanisms implemented within a network device having a symmetric multiprocessing architecture, the plurality of operations comprising:

• receiving a first packet in a session;
• performing a route lookup to determine a route for the first packet;
• caching a reference to the route in the session;
• caching a reference to the session and a neighbor in a tunnel within which packets in the session are forwarded;
• comparing a first route version number cached in the session with a second route version number in a route table corresponding to the route referenced by a route index in the session;
• determining whether the route is stale based on the first and second route version numbers;
• performing another route lookup to update the route in response to determining that the route is stale;
• and
• using cached reference to the session in the tunnel for forwarding subsequent packets in the session.