![](/images/backgrounds/285815/hp-4100gl-users-manual-549937217x1.png)
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| Using Authorized IP Managers | ||
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| Building IP Masks | ||
Figure | |||||||
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| 1st | 2nd | 3rd | 4th |
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| Octet | Octet | Octet | Octet |
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IP Mask | 255 | 255 | 255 | 0 | The “255” in the first three octets of the mask specify that only the exact |
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Authorized | 10 | 28 | 227 | 125 | value in the octet of the corresponding IP address is allowed. However, | ||
the zero (0) in the 4th octet of the mask allows any value between 0 and | |||||||
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Manager IP
255 in that octet of the corresponding IP address. This mask allows switch access to any device having an IP address of 10.28.227.xxx, where xxx is any value from 0 to 255.
IP Mask | 255 | 255 | 255 | 249 |
Authorized | 10 | 28 | 227 | 125 |
IP Address |
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In this example (figure
4th Octet of IP Mask: | 249 |
4th Octet of Authorized IP Address: 5
Bit Numbers | Bit |
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| Bit |
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| Bit | Bit |
| Bit |
| Bit | |
| 7 | 6 | 5 | 4 | 3 |
| 2 | 1 | 0 | ||||||
Bit Values | 128 | 64 | 32 | 16 | 8 |
| 4 | 2 | 1 | ||||||
4th Octet of |
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IP Mask (249) |
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4th Octet of |
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IPAuthorized |
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Address (125) |
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Bits 1 and 2 in the mask are “off”, and bits 0 and 3 - 7 are “on”, creating a value of 249 in the 4th octet .
Where a mask bit is “on”, the corresponding bit setting in the address of a potentially authorized station must match the IP Authorized Address setting for that same bit. Where a mask bit is “off” the corresponding bit setting in the address can be either “on” or “off”. In this example, in order for a station to be authorized to access the switch:
•The first three octets of the station’s IP address must match the Authorized IP Address.
•Bit 0 and Bits 3 through 6 of the 4th octet in the station’s address must be “on” (value = 1).
•Bit 7 of the 4th octet in the station’s address must be “off” (value = 0).
•Bits 1 and 2 can be either “on” or “off”.
This means that stations with the IP address 13.28.227.X (where X is 121, 123, 125, or 127) are authorized.
Figure