Shulou(Shulou.com)06/02 Report--

Concept:

Directed broadcast address: generally refers to all ip addresses on the same network segment.

Local broadcast address: all ip addresses. From 0. 0 . 0 . 1-255. two hundred and fifty five. two hundred and fifty five. two hundred and fifty four

For example:

one hundred and ninety two. one hundred and sixty eight. one. 1Accord 24, which is a standard class c ip address.

one hundred and ninety two. one hundred and sixty eight. one. 0 is the network segment number

one hundred and ninety two. one hundred and sixty eight. one. 255 is the broadcast address (directed broadcast address)

two hundred and fifty five. two hundred and fifty five. two hundred and fifty five. 255 is the broadcast address (local broadcast address)

The difference between them is that the router sends a directed broadcast address instead of a local broadcast address.

This topic involves a knowledge point that everyone is easy to confuse. Routers do not forward broadcasts of this network segment, but forward broadcasts that lead to other network segments!

220.94.47.255 255.255.240.0 is the broadcast address within the network segment 220.94.36.9 255.255.240.0, 220.93.28.8

Using the subnet mask of 255.255.240.0, it is obvious that they are not in the same network segment. When 220.93.28.8 gives the broadcast address to the gateway to determine how to forward the broadcast, once again, all broadcast layer 2 addresses are FF.FF.FF.FF.FF.FF, but the layer 3 address is different. What he can do at will is 192.168.1.255, 24192.168.2.255, 24 192.168.3.255and24 192.168.3.255and23.

172.31.255.255Compact 20 switch only looks at the layer 2 address and certainly does not understand how to forward it to a specific network segment, while routing combined with layer 3 address

You can judge that this is a directed broadcast of another network segment, so as to forward it!

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