ICP DAS USA MSM-6226 - Manual (Page 58)

Publication date:March., 2011
Revision A1
46
3-3. DHCP Relay
The Dynamic Host Configuration Protocol (DHCP) is a service that runs at the
application layer of the TCP/IP protocol stack to dynamically assign IP addresses to
DHCP clients. DHCP clients request IP addresses, and obtain leases for IP
addresses from the DHCP server.
The DHCP Relay Agent makes it possible for DHCP broadcast messages to
be sent over routers that do not support forwarding of these types of messages. The
DHCP Relay Agent is therefore the routing protocol that enables DHCP clients to
obtain IP addresses from a DHCP server on a remote subnet, or which is not
located on the local subnet. If you have no configured DHCP Relay Agent, your
clients would only be able to obtain IP addresses from the DHCP server which is on
the same subnet.
If you are using the switches to insert DHCP Option 82 information and you
are also using as DHCP relay-agents (via ‘ip helper-address’), you’ll notice right
away that your Option 82 enabled DHCP requests are not being forwarded by your
switches.
Function name:
Config
Function description:
The switch to enable clients to obtain IP addresses from a DHCP server on a
remote subnet, you have to configure the DHCP Relay Agent on the subnet that
contains the remote clients, so that it can relay DHCP broadcast messages to your
DHCP server.
Parameters description:
DHCP Relay State:
Fig. 3-13-1