• A forwarding table is an optimized version of a routing table, forwarding table generally consists of the headers and corresponding outgoing link interfaces.
• The router may connect to number of outgoing link interfaces. Thus, the router looks into forwarding table to decide that to which outgoing link, the input packet to be forwarded.
• A forwarding table consist subset of routes from a routing table selected by routing algorithm to forward a packet. Forwarding table in a router is used for a faster look up of destination addresses. A forwarding table can be considered as a cached version of routing table consisting of the MAC address of the best interface through which a packet can be forwarded.
• Forwarding tables are usually distributed over the modular systems and are stored on TCAM content addressable memory which is costly and fast.
Therefore the role of the forwarding table is to help the router in deciding that to which outgoing link, the input packet to be forwarded.
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