Operation of Process Switching
When a router routes a packet (that is, performs packet switching), the router removes the packet’s Layer 2 header, examines the Layer 3 addressing, and decides how to forward the packet. The Layer 2 header is then rewritten (which might involve changing the source and destination MAC addresses and computing a new cyclic redundancy check [CRC]), and the packet is forwarded out an appropriate interface. With process switching, as illustrated in Figure 11-1, a router’s CPU becomes directly involved with packet-switching decisions. As a result, the performance of a router configured for process switching can suffer significantly.
Figure 11-1 Data Flow with Process Switching
An interface can be configured for process ...
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