2)
Specify the DHCP Server which assigns IP addresses actually.
Option 82
On this switch, Option 82 is used to record the location of the DHCP Client, the ethernet port
and the VLAN, etc. Upon receiving the DHCP-REQUEST packet, the switch adds the Option 82
field to the packet and then transmits the packet to DHCP Server. The Server can be
acquainted with the location of the DHCP Client via Option 82, so as to locate the DHCP Client,
and assign the distribution policy of IP addresses and the other parameters for fulfilling the
security control and account management of the client.
Option 82 can contain 255 sub-options at most. If Option 82 is defined, at least one sub-option
should be defined. This Switch supports two sub-options, Circuit ID and Remote ID. Since there
is no universal standard about the content of Option 82, different manufacturers define the
sub-options of Option 82 to their need. For this Switch, the sub-options are defined as follows:
The Circuit ID is defined to be the number and VLAN of the port which receives the DHCP
Request packets. The Remote ID is defined to be the MAC address of DHCP Relay device which
receives the DHCP Request packets from DHCP Clients. Furthermore these two parameters
also can be manually configured.
The format of Option 82 defined on the switch by default is given in the following figure. The
numbers in parentheses indicate the size of each field in octets. By default, sub-option1 is
Circuit ID option recording the VLAN and ethernet port information, while sub-option2 is
Remote ID option recording the MAC address information of the client. You can define the
sub-options manually.
Figure10-18 Option 82
Note:
The option 82 parameters configured on the switch should base on and meet the requirement
of the network.
The DHCP Relay, allowing the clients to get the IP address from the server in another subnet, is
implemented on the
DHCP Relay
page. When the DHCP Server is enabled, the DHCP Relay will
be enabled too.
10.5.1
Global Config
This page allows you to enable the DHCP Relay function.
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