Patent ID: 7493412

Claim:
A method comprising: processing a data packet, having a destination IP address (d), towards a routing destination; determining a default-route-prefix (P d ) that is a part of the destination IP address (d) and is provided only in a routing table cache (L 1 ) during a default-route determination step, when in the routing table cache (L 1 ) and in a routing table (L 2 ), there is no entry with a destination address prefix that is a prefix of the destination IP address (d), wherein the default-route-prefix (P d ) is a shortest prefix that covers only destination IP addresses that have no matching prefix in the routing table (L 2 ), wherein the routing table cache (L 1 ) comprises a prefix that is a part of another destination IP address and the destination IP address (d); performing a first lookup step for the destination IP address (d), the destination address prefix being a prefix of the destination IP address (d) is searched in the routing table cache (L 1 ), and, if said first lookup step results in not finding such destination address prefix, performing a second lookup step for said destination IP address (d), the destination address prefix being a prefix of the destination IP address (d) is searched in the routing table (L 2 ), wherein if the second lookup step on the routing table (L 2 ) results in finding the destination address prefix being said prefix of the destination IP address (d) a matching destination address prefix, the found destination address prefix entry is entered into the routing table cache (L 1 ) in a cache update step, and the data packet is forwarded in a destination forwarding step to a corresponding routing destination.