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Chapter 15
| IP Services
Dynamic Host Configuration Protocol
Configuring
DHCP Relay
◆
Text – A text string. (Range: 1-32 characters)
Web Interface
To configure a DHCP client identifier:
1.
Click IP Service, DHCP, Client.
2.
Mark the check box to enable this feature. Select the default setting, or the
format for a vendor class identifier. If a non-default value is used, enter a text
string or hexadecimal value.
3.
Click Apply.
Figure 339: Specifying A DHCP Client Identifier
Use the IP Service > DHCP > Relay page to configure DHCP relay service for
attached host devices, including DHCP option 82 information. DHCP provides an
option for sending information about its DHCP clients to the DHCP server
(specifically, the interface on the relay server through which the DHCP client
request was received). Also known as DHCP Relay Option 82, it allows compatible
DHCP servers to use this information when assigning IP addresses, or to set other
services or policies for clients.
Option 82 information contains information which can identify both the relay
agent and the interface through which the DHCP request was received:
◆
The DHCP Relay Information Option Remote ID (RID) is the access node
identifier – a string used to identify the switch to the DHCP server.
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The DHCP Relay Information Option Fields are the Option 82 circuit
identification fields (CID – including VLAN ID, stack unit, and port). These fields
identify the requesting device by indicating the interface through which the
relay agent received the request.
If DHCP relay is enabled, and this switch sees a DHCP client request, it inserts its
own IP address into the request so that the DHCP server will know the subnet
where the client is located. Depending on the selected frame format set for the
remote-id, this information may specify the MAC address, IP address, or an arbitrary
string for the requesting device (that is, the relay agent in this context).
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