Tag edge routers and tag switches use standard routing protocols to identify routes through the internetwork. When the Tag routers receive this TDP information they build a forwarding database. When a tag edge router receives a packet it analyzes the network layer header, performs applicable network layer services, selects a route for the packet from its routing tables, applies a tag, and forwards the packet to the next hop tag switch. The tag switch receives the tagged packet and switches the packet based solely on the tag. The packet reaches the tag edge router at the egress point of the network, the tag is stripped off and the packet delivered as usual.
Paper presents a forwarding table data struct.
Such forwarding tables are small enough to fit in the cache of a conventional general purpose processor. The forwarding tables are very small, a large routing table with 40,000 routing entries can be compacted to a forwarding table of 150-160 Kbytes. A lookup typically requires less than 100 instructions on an Alpha, using eight memory references accessing a total of 14 bytes.