ECS4100 Series Web Management Guide-R07

Table Of Contents
Chapter 19
| IP Services
Dynamic Host Configuration Protocol
– 711 –
DHCP relay configuration will be disabled if an active DHCP server is detected
on the same network segment.
If DHCP Option Policy is set to drop, the original DHCP request packet flooded
to the receiving VLAN is received but not relayed to the DHCP server.
If DHCP Option Policy is set to replace, the DHCP request packet’s option 82
content (RID and CID sub-option) is replaced with the relay agent switchs
address information. The agent then unicasts the modified DHCP Request
packet to the DHCP server.
If DHCP Option Policy is set to keep, the DHCP request packet’s option 82
content is unmodified. However the switch address information of the relay
agent is additionally added into the DHCP request packet. The agent then
unicasts the modified DHCP Request packet including the original RID and CID
to the DHCP server.
Parameters
These parameters are displayed:
Insertion of Relay Information– Check to enable the Option 82 information to
be included with the DHCP Request forwarded to the DHCP server.
DHCP Option Policy– Select either Drop, Keep or Replace.
DHCP Sub-option FormatSelect to include or not include the extra sub-
types with the Option 82 Sub-option information.
Web Interface
To configure L2 DHCP relay service:
1. Click IP Service, DHCP, Relay - (just above Dynamic Provision)
2. Enter up to five IP addresses for DHCP servers or relay servers in order of
preference for any VLAN under the Server heading in the fields provided.
3. Select the Option 82 parameter settings under the Information heading.
4. Click Apply.