TP-Link T2600G-28MPS T2600G-28MPSUN V1 User Guide - Page 210

IP Detection, Policy of IP Assignment, Tips for Con DHCP Server Function

Page 210 highlights

Figure 10-15 DHCP Server Application To guarantee the process of assigning IP address fluency and in safety, and to keep the network run steadily, the DHCP Server function on the switch performs the following tasks.  Create different IP pool for every VLAN. The device in different VLAN can get the IP address in different subnet.  When receiving a DHCP-DISCOVER packet from the client, the switch judges the VLAN which the ingress port belong to, and chooses the IP in the same subnet with the VLAN interface to assign to the client.  With a DHCP Relay running between the client and the server, when receiving a DHCP-DISCOVER packet transmitting from the Relay, the switch will choose the IP from the IP pool in the same subnet with the Relay's IP to assign to the client. If the IP pool is not configured on the switch or the configured IP pool doesn't match the Relay's network segment, the client may not get network parameters successfully.  The switch can detect the IP address automatically before assigning it to avoid conflict.  IP Detection To avoid IP conflict, the switch will detect the IP address to be assigned in LAN through Ping test. The DHCP server will send the Ping test packet with the destination IP being the IP address to be assigned. If the server receives the Reply packet from the destination host in the ping time, it means that the IP address has been used, and the server will choose another IP as destination IP to test again. The server will assign the IP address if the server not receives the Reply packet in the Ping time.  Policy of IP Assignment The switch chooses the IP assigned to clients based on the rules shown as follows. 1) First, the server will choose the IP which has been bound to the client manually. 2) Then, the server will assign the IP which has been assigned to the client once. 3) For the next, the server will assign the IP which is specified in the DHCP-DISCOVER packet from the client. 4) At last, the server will choose the first IP from the IP pool which has not been assigned.  Tips for Configure DHCP Server Function 199

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Figure 10-15 DHCP Server Application
To guarantee the process of assigning IP address fluency and in safety, and to keep the network
run steadily, the DHCP Server function on the switch performs the following tasks.
Create different IP pool for every VLAN. The device in different VLAN can get the IP address
in different subnet.
When receiving a DHCP-DISCOVER packet from the client, the switch judges the VLAN
which the ingress port belong to, and chooses the IP in the same subnet with the VLAN
interface to assign to the client.
With a DHCP Relay running between the client and the server, when receiving a
DHCP-DISCOVER packet transmitting from the Relay, the switch will choose the IP from the
IP pool in the same subnet with the Relay’s IP to assign to the client. If the IP pool is not
configured on the switch or the configured IP pool doesn’t match the Relay’s network
segment, the client may not get network parameters successfully.
The switch can detect the IP address automatically before assigning it to avoid conflict.
IP Detection
To avoid IP conflict, the switch will detect the IP address to be assigned in LAN through Ping test.
The DHCP server will send the Ping test packet with the destination IP being the IP address to be
assigned. If the server receives the Reply packet from the destination host in the ping time, it
means that the IP address has been used, and the server will choose another IP as destination IP
to test again. The server will assign the IP address if the server not receives the Reply packet in
the Ping time.
Policy of IP Assignment
The switch chooses the IP assigned to clients based on the rules shown as follows.
1)
First, the server will choose the IP which has been bound to the client manually.
2)
Then, the server will assign the IP which has been assigned to the client once.
3)
For the next, the server will assign the IP which is specified in the DHCP-DISCOVER packet
from the client.
4)
At last, the server will choose the first IP from the IP pool which has not been assigned.
Tips for Configure DHCP Server Function
199