Configuring The Dhcp Relay Agent To Support Option 82 - 3Com MSR 50 Series Configuration Manual

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Configuring the DHCP
Relay Agent to Support
Option 82
To do...
Configure the DHCP relay
agent to support authorized
ARP
Authorized ARP can only be configured on Layer 3 interfaces.
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Disabling the DHCP relay agent to support authorized ARP will not delete
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dynamic bindings, but will notify authorized ARP to delete the corresponding
authorized ARP entries.
Since the DHCP relay agent does not notify the authorized ARP module of the
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static bindings, you need to configure the corresponding static ARP entries for
authorized ARP.
For more information about authorized ARP, refer to
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ARP" on page 555.
Enabling unauthorized DHCP servers detection
There are invalid DHCP servers on networks, which reply DHCP clients with wrong
IP addresses. These invalid DHCP servers are unauthorized DHCP servers.
With this feature enabled, upon receiving a DHCP message with the siaddr field (IP
address of the server assigning IP addresses to clients) not being 0 from a client,
the DHCP relay agent will record the value of the siaddr field and the information
on the interface receiving the DHCP message. The administrator can use this
information to check out any DHCP unauthorized servers.
To enable unauthorized DHCP server detection, use the following commands:
To do...
Enter system view
Enable unauthorized DHCP
server detection
With the unauthorized DHCP server detection enabled, the device puts a record
once for each DHCP server. The administrator needs to find unauthorized DHCP
servers from the log information. After the recorded information of a DHCP server
is cleared, a new record will be put for the DHCP server.
Prerequisites
You need to complete the following tasks before configuring the DHCP relay
agent to support Option 82.
Enabling DHCP
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Enabling the DHCP relay agent on the specified interface
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Correlating a DHCP server group with relay agent interfaces
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Configuring the DHCP relay agent to support Option 82

Use the following commands for this configuration:
Configuring the DHCP Relay Agent
Use the command...
dhcp update arp
Use the command...
system-view
dhcp relay server-detect
595
Remarks
Required
Not supported by default.
"Configuring Authorized
Remarks
-
Required
Disabled by default