Patent Number: 6,295,296

Title: Use of a single data structure for label forwarding and imposition

Abstract: A router (10) in a packet-based telecommunications system receives incoming packets that may have "shim" headers between their link-layer and network-layer headers. The shim header contains one or stack entries, each of which includes a label, and the router can employ the label in the top stack entry as direct index into a forwarding table that the router uses to forward the packet. Among the forwarding table's contents is a pointer to a replacement data structure (62). To assemble an outgoing packet to be forwarded in the incoming packet's place, the router replaces the incoming packet's link-layer header and any top shim-header stack entry with the replacement data structure. The router employs this mechanism (1) to impose a shim header on packets that did not have them previously, (2) to replace shim-header stack entries for forwarding to subsequent routers, and (3) to remove shim headers.

Inventors: Tappan; Daniel C. (Boxborough, MA)

Assignee: Cisco Technology, Inc.

International Classification: H04L 29/06 (20060101); H04L 12/56 (20060101); H04L 012/56 ()

Expiration Date: 09/25/2018