TP-Link Jetstream T1500G-8T User Manual page 454

Configuring DHCP Service
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 customized circuit ID and default remote ID
in TLV format. According to packet format described in
options of the two groups are as shown in the following table.
Table 4-2
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 8 byte long in TLV format, one
# byte for Type, one byte for Length, and 6 bytes for Value. Therefore, the offset is 2 and the
length is 6.
# Similarly, the offset of the agent remote ID is 2 and the length is 6.
class "Group1" {
match if substring (option agent.circuit-id, 2, 6) = "Group1"
}
class "Group2" {
match if substring (option agent.circuit-id, 2, 6) = "Group2"
}
# Create two IP Address pools in the same subnet.
# Assign different IP addresses to the DHCP clients in different groups.
subnet 192.168.10.0 netmask 255.255.255.0 {
option routers 192.168.10.1;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.10.1;
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Sub-options of Group1 and Group 2
Sub-option Type (Hex)
Circuit ID 00
Remote ID 00
Circuit ID 00
Remote ID 00
and substring (option agent.remote-id, 2, 6) = 00:00:ff:ff:27:12;
and substring (option agent.remote-id, 2, 6) = 00:00:ff:ff:27:12;
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Table 1-1
Length (Hex) Value
"Group1" as an ASCII string (or
06
47:72:6F:75:70:31 in hexadecimal)
06 00:00:FF:FF:27:12
"Group2" as an ASCII string (or
06
47:72:6F:75:70:32 in hexadecimal)
06 00:00:FF:FF:27:12
Configuration Examples
and Table 1-2, the sub-
User Guide 431