ZyXEL Communications XS3800-28, User Manual, Page: 481 / 789

Chapter 64 DHCP
XS3800-28 User’s Guide
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Figure 374 NETWORKING > DHCP > DHCPv4 Server > Add/Edit
The following table describes the labels in this screen.
64.8.2 Example: DHCP Relay for Two VLANs
The following example displays two VLANs (VIDs 1 and 2) for a campus network. Two DHCP servers are
installed to serve each VLAN. The system is set up to forward DHCP requests from the dormitory rooms
(VLAN 1) to the DHCP server with an IP address of 192.168.1.100. Requests from the academic buildings
(VLAN 2) are sent to the other DHCP server with an IP address of 172.16.10.100.
Table 249 NETWORKING > DHCP > DHCPv4 Server > DHCP Server Setup > Add/Edit
LABEL DESCRIPTION
VID Enter the ID number of the VLAN to which these DHCP settings apply.
Client IP Pool
Starting Address Specify the first of the contiguous addresses in the IP address pool.
Size of Client IP
Pool Specify the size, or count of the IP address pool. The Switch can issue from 1 to 253 IP addresses
to DHCP clients.
IP Subnet Mask Enter the subnet mask for the client IP pool.
Default
Gateway Enter the IP address of the default gateway device.
Primary/
Secondary DNS
Server Enter the IP addresses of the DNS servers. The DNS servers are passed to the DHCP clients along
with the IP address and the subnet mask.
Lease Time Select Infinite to have the binding always valid. Select the second radio button to set up the
binding’s valid days, hours and minutes.
Unavailable
Lease Time Unavailable lease time is the lease time of an IP address that is distributed by other unknown
DHCP servers to other devices. A DHCP client rejects the IP address assigned by the Switch
when it discovers the assigned IP is already in use by other devices. When an IP is in use by other
devices, the Switch cannot assign this unavailable IP to the Switch’s DHCP client. The Switch will
mark the IP as an unavailable IP and removes it from the IP address pool. The Switch will not
assign the unavailable IP to DHCP clients until
Unavailable Lease Time expires.
Set up the days, hours, and minutes of unavailable lease time.