Switches

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Routing can be achieved using two mechanisms:
1
Source-path, the entire path to the destination is stored in the packet header at the source location.
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When a packet enters the switch, the outgoing port is determined from the header.
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Used routing data is stripped from the header and routing information for the next switch is now in the front.
2
Table-based routing, the switch must have a complete routing table that determines the corresponding port for each destination.
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When a packet enters the switch, a table lookup will determine the outgoing port.

Figure 7.6: Source-path routing vs. table-based routing.
\includegraphics[scale=0.8]{figures/routing.ps}

Cem Ozdogan 2010-12-27