Tag Functions
In conventional Layer 3 forwarding, as a packet traverses the network, each router extracts all the information relevant to forwarding the packet from the Layer 3 header. This information is then used as an index for a routing table lookup to determine the packet's next hop.
In the most common case, the only relevant field in the header is the destination address field, but in some cases other header fields may also be relevant. As a result, the header analysis must be done independently at each router through which the packet passes, and a complicated lookup must also be done at each router.
In Tag Switching, the analysis of the Layer 3 header is done just once. The Layer 3 header is then mapped into a fixed-length, unstructured ...
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