Dell Force10 S4810P Configuration Manual page 386

When
ip helper-address
system rewrites packets received from the client and forwards it via unicast; the system rewrites the
destination IP address and writes its own address as the relay device. Responses from the server are unicast
back to the relay agent on port 68 and the relay agent rewrites the destination address and forwards the
packet to the client subnet via broadcast.
Note: DHCP Relay is not available on Layer 2 interfaces and VLANs.
HCP Relay Device
Broadcast
Source IP : 0.0.0.0
Destination IP: 255.255.255.255
Source Port: 68
Destination Port: 67
Relay Agent Address: 0.0.0.0
To view the
EXEC privilege mode, as shown in the following example.
R1_E600#show ip int gig 1/3
GigabitEthernet 1/3 is up, line protocol is down
Internet address is 10.11.0.1/24
Broadcast address is 10.11.0.255
Address determined by user input
IP MTU is 1500 bytes
Helper address is 192.168.0.1
Directed broadcast forwarding is disabled
Proxy ARP is enabled
Split Horizon is enabled
Poison Reverse is disabled
ICMP redirects are not sent
ICMP unreachables are not sent
386
| Dynamic Host Configuration Protocol (DHCP)
is configured, the system listens for DHCP broadcast messages on port 67. The
Broadcast
Source IP : 10.11.1.5
Destination IP: 255.255.255.255
Source Port: 67
Destination Port: 68
1/3
R1(conf-if-gi-1/3)#show config
!
interface GigabitEthernet 1/3
ip address 10.11.0.3/24
ip helper-address 10.11.1.5
ip helper-address 10.11.2.5
no shutdown
configuration for an interface, use the command
ip helper-address
192.168.0.2
DHCP Server
10.11.2.5
Unicast
Source IP : 10.11.1.5
Destination IP: 10.11.0.3
Source Port: 67
Destination Port: 68
1/4
Unicast
Source IP : 10.11.1.3
Destination IP: 10.11.1.5
Source Port: 67
Destination Port: 67
Relay Agent Address: 10.11.0.3
DHCP Server
10.11.1.5
DHCP 001
from
show ip interface