Option 184 Supporting Configuration 139
The sub-option 3 of option 184 comprises two parts, which carry the previously
mentioned two items respectively. A flag value of 0 indicates that the voice VLAN
identification function is not enabled, in which case the information carried by the
VLAN ID part will be neglected. A flag value of 1 indicates that the voice VLAN
identification function is enabled.
Fail-Over Call Routing
The fail-over call routing sub-option carries the IP address for fail-over call routing and
the associated dial number. This sub-option is the fourth sub-option of option 184,
that is, sub-option 4.
The IP address for fail-over call routing and the dial number in sub-option 4 of option
184 refer to the IP address and dial number of the session initiation protocol (SIP)
peer. When the NCP server and alternate NCP server (if configured) are unreachable, a
SIP user can use the configured IP address and dial number of the peer to establish a
connection and communicates with the peer SIP user.
For the configurations specifying to add sub-option 2, sub-option 3, and sub-option 4
in the response packets to take effect, you must configure the DHCP server to add
sub-option 1.
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 support on DHCP server is
as follows:
1A DHCP client sends to the DHCP server a request packet carrying option 55, which
indicates the client requests the configuration parameters of option 184.
2The 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 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.
Prerequisites The following are required before you configuring the option 184 supporting
function.
■The network parameters, address pools, and lease time are configured.
■The DHCP server and the DHCP clients can communicate properly with each
other.
Configuring the Option
184 Supporting Function
You can configure the sub-options of option 184 in system view, interface view, and
DHCP address pool view. Note that an interface-based address pool is needed for the
first two methods.