3Com 5500-EI PWR Install Manual page 593

Mechanism of using Option 184 on DHCP server
The DHCP server encapsulates the information for Option 184 to carry in the response packets sent to
the DHCP clients. Supposing that the DHCP clients are on the same segment as the DHCP server, the
mechanism of Option 184 on the DHCP server is as follows:
1) A DHCP client sends to the DHCP server a request packet carrying Option 55, which indicates the
client requests the configuration parameters of Option 184.
2) The DHCP server checks the request list in Option 55 carried by the request packet, and then adds
the sub-options of Option 184 in the Options field of the response packet to be sent to the DHCP
client.
Only when the DHCP client specifies in Option 55 of the request packet that it requires Option 184, does
the DHCP server add Option 184 in the response packet sent to the client.
Configuring Option 184 Parameters for the DHCP Client with Voice Service
Follow these steps to configure Option 184 parameters for the DHCP client with voice service:
To do...
Enter system view
Enter DHCP address pool view
Specify the IP address of the
primary network calling
processor
Specify the IP address of the
backup network calling
processor
Configure the voice VLAN
Specify the failover IP address
Specify an IP address for the network calling processor before performing other configuration.
Use the command...
system-view
dhcp server ip-pool
pool-name
voice-config ncp-ip
ip-address
voice-config as-ip ip-address
voice-config voice-vlan
vlan-id { disable | enable }
voice-config fail-over
ip-address dialer-string
2-13
Remarks
—
—
Required
Not specified by default.
Optional
Not specified by default.
Optional
Not configured by default.
Optional
No failover IP address is
specified by default.