- Operation of the DHCP protocol:
- When a host computer
boots (starts).
the computer sends a
broadcast
physical (e.g., Ethernet) frame
containing a
DHCP discovery message:
DHCP_discover( Physical-address of computer )Example:
- This message will be
received by
all nodes
on the network, but:
- Only the DHCP server will process the DHCP_discover request.
- The DHCP server will
send back a
DHCP response
containing:
- the IP address for the
requesting host
- the IP address of the default router
Example:
- the IP address for the
requesting host
- When a host computer
boots (starts).
the computer sends a
broadcast
physical (e.g., Ethernet) frame
containing a
DHCP discovery message:
- DHCP protocol
using static address assignment:
- Suppose
the host computer
with
Ethernet Address E7
boots and
sends a
DHCP discovery message:
- Only the
node with a DHCP server
will process the
request:
- The DHCP server
sends back a
DHCP reply containing the
IP address that
corresponds to the
given physical (Ethernet) address:
- The node can now
configure its
forwarding and routing tables:
- Suppose
the host computer
with
Ethernet Address E7
boots and
sends a
DHCP discovery message:
- DHCP with
dynamic address assignment:
- The DHCP server
maintains a list of
unassigned IP numbers :
- When the DHCP server receives a DHCP discover request, it selects an unused IP address, marks it as unused and sends a DHCP reply.
- The DHCP server
maintains a list of
unassigned IP numbers :
- Implementation note:
- Most(all ?)
home routers sold today
has a DHCP server
running inside the
router.
E.g.:
- In the MathCS department,
the DHCP server is running on a
UNIX machine....
(Easier to manage)
- Most(all ?)
home routers sold today
has a DHCP server
running inside the
router.