Alcatel Omni Switch/Router, User Manual

Page: 770 / 1100

BOOTP/DHCP Relay
Page 26-6
External BOOTP Relay
The
BOOTP
relay may be configured on a router that is external to the switch. In this applica-
tion example the switched network has a single AutoTracker Group configured with multiple
segments. All of the network hosts are
DHCP
-ready, meaning they obtain their network
address from the
DHCP
server. The
DHCP
server resides behind an external network router,
which supports the
BOOTP
relay functionality.
One requirement for routing
DHCP
frames is that the router must support
BOOTP
relay func-
tionality to be able to forward
DHCP
frames. In this example,
BOOTP
relay is supported within
an external router, which forwards request frames from the incoming router port to the outgo-
ing router port attached to the Omni Switch/Router.
DHCP Clients are Members of the Same VLAN
The external router inserts the subnet address of the first hop segment into the
DHCP
request
frames from the
DHCP
clients. This subnet address allows the
DHCP
server to locate the
segment that the requesting client resides on. In this example, all clients attached to the Omni
Switch/Router are
DHCP
-ready and will have the same subnet address (130.0.0.0) inserted into
each of the requests by the router’s
BOOTP
relay function. The
DHCP
server will assign a
different IP address to each of the clients. The switch does not need an IP address assigned
and all
DHCP
clients will be members of either a default
VLAN
or an IP protocol
VLAN
.
Omni Switch/Router
12345678
123456
Group 1
DHCP Client s
130.0.0.11 130.0.0.12
DHCP Clients
130.0.0.14
130.0.0.13
DHCP Client
s
130.0.0.15
DHCP Server
125.0.0.1
125.0.0.2
External
BOOTP
Relay
DHCP Client