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10.2 | |
Overview of Transport Layer Ports | |
| 10.2.6 | |
Comparison of MAC addresses, IP addresses, and port numbers |
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These three methods of addressing are
often confusing, but this can be avoided if the addresses are
explained in reference to the OSI model. Port numbers are located at
the transport layer and are serviced by the network layer. The network
layer assigns the logical address (IP address) and is then serviced by the
data link layer which assigns the physical address (MAC address). A good analogy can be made with a
normal letter. The address on a letter consists of a name, street,
city, and state. These can be compared to the port, MAC, and IP
address used for network data. The name on the envelope would be
equivalent to a port number, the street address is the MAC, and the
city and state is the IP address. Multiple letters can be mailed to
the same street address, city and state, but contain different names
on the letters. For instance, two letters could be mailed to the same
house with one addressed to “John Doe” and the other to “Jane Doe”.
This is analogous to multiple sessions with different port numbers.
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