Westermo RedFox Series - Manual (Page 495)

Westermo OS Management Guide
Version 4.17.0-0
22.1.4.1 IP per port on local DHCP server ports
With DHCP option 82, a relay agent can inform the DHCP server which port
(circuit-id) the client is connected to, thereby enabling the server to assign IP
addresses per port. In WeOS, the same approach is used when you wish to hand
out IP addresses per port on the DHCP server’s local ports.
CCTV PC
Relay Agent
DHCP Server
1 2 3 6 5 4
VLAN 1 VLAN 2
192.168.2.0/24 192.168.5.0/24
.49 .100
WeOS Router
Figure 22.2: Running both a DHCP Server and a DHCP Relay Agent on the same
unit enables you to assign IP address per port on the DHCP server unit.
Fig. 22.2 illustrates an example where the WeOS unit is configured to hand out
addresses on interface ”vlan2” (subnet 192.168.5.0/24). Regular hosts, such as
the PC, will be assigned their IP addresses from an address pool, but the unit
attached to port 6 should always be assigned IP address 192.168.5.49. This
can be achieved by configuring a DHCP relay agent on interface ”vlan2”, and
to instruct the relay agent to forward DHCP request to the local DHCP server
(address ”127.0.0.1”). Relevant parts of the WeOS configuration is listed in
fig. 22.3 .
The WeOS DHCP relay will by default pass its base-MAC address 3 as remote-id
(”00:07:7c:00:30:b0” in the configuration example in fig. 22.3 .). As the base-
MAC is unit specific, this setting will not work if you wish to replace the unit,
but keep the same configuration file. In such situations, using ”system-name” or
”ip” as remote-id is recommended, see
sections 23.2.1 (Web) and 23.3.9 (CLI)
for more information. An example using the system name as remote-id is given
in
fig. 22.4 .
3 To find the base MAC of your WeOS unit, see sections 4.4.2 (Web) or 7.3.2 (CLI).
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