Operation Manual – DHCP
H3C S5600 Series Ethernet Switches
Chapter 2 DHCP Server Configuration
2-16
Sub-option
Feature
Function
Note
Fail-Over Call
Routing
(sub-option 4)
The fail-over call
routing sub-option
carries the IP
address for
fail-over call
routing and the
associated dial
number. 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 is
unreachable, a
SIP user can use
the configured IP
address and dial
number of the peer
to establish a
connection and
communicate with
the peer SIP user.
—
Note:
For the configurations specifying to add sub-option 2, sub-option 3, and sub-option 4 in
the response packets to take effect, you need to configure the DHCP server to add
sub-option 1.
III. 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.