Configuring The Dhcp Server - TP-Link Jetstream T1500G-8T User Manual

Configuring DHCP Service
Switch#show ip dhcp relay information interface
Interface Option 82 Status Operation Strategy Format Circuit ID
--------- ----------------
Gi1/0/1
Gi1/0/2
...

4.2.4 Configuring the DHCP Server

On the DHCP server, you need to create two DHCP classes to identify the Option 82
payloads of DHCP request packets from Group 1 and Group 2, respectively.
In this example, the DHCP relay agent uses the default circuit ID and remote ID in TLV
format. According to packet formats described in
of the two groups are as shown in the following table.
Table 4-1
Group
1
2
The configuration file /etc/dhcpd.conf of the Linux ISC DHCP Server is:
ddns-update-style interim;
ignore client-updates;
# Create two classes to match the pattern of Option 82 in DHCP request packets from
# Group 1 and Group 2, respectively.
# The agent circuit ID inserted by the DHCP relay switch is 6 bytes long in TLV format, one
# byte for Type, one byte for Length, and 4 bytes for Value. Therefore, the offset is 2 and the
length is 4.
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Note:
•
Make sure the DHCP server supports Option 82 and more than one DHCP address pool.
• To make sure the DHCP server can reach the computers, you can create static routes or enable
dynamic routing protocol like RIP on the DHCP server.
• In this section, we use different notations to distinguish ASCII strings from hexadecimal
numbers. An ASCII string is enclosed with quotation marks, such as "123", while a hexadecimal
number is divided by colon into parts of two digits, such as 31:32:33.
Sub-options of Group1 and Group 2
Sub-option Type (Hex)
Circuit ID 00
Remote ID 00
Circuit ID 00
Remote ID 00
search engine
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Replace Normal Default:VLAN-PORT ...
Replace Normal Default:VLAN-PORT ...
Table 1-1
Length (Hex) Value (Hex)
04 00:02:00:01
06 00:00:FF:FF:27:12
04 00:02:00:02
06 00:00:FF:FF:27:12
Configuration Examples
...
--------- ...
and Table 1-2, the sub-options
User Guide 425