Option 184 Supporting Configuration - 3Com 5500-SI Configuration Manual

138 C 10: DHCP S
HAPTER
Option 184
Supporting
Configuration
C
ERVER ONFIGURATION
receives a response or the number of the sent ICMP packets reaches the specified
maximum number. The DHCP server assigns the IP address to the DHCP client only
when no response is received during the whole course. Such a mechanism ensures an
IP address is assigned to one DHCP client exclusively.
A DHCP server performs ping tests to detect potential IP address conflicts, while a
DHCP client uses ARP packets to detect IP address conflicts
.
Table 128 Configure IP address detecting
Operation
Enter system view
Set the maximum
number of ICMP
packets a DHCP server
sends in a ping test
Set the response
timeout time of each
ICMP packet
Option 184 is an RFC reserved option, and the information it carries can be
customized. 3Com defines four proprietary sub-options for this option, enabling the
DHCP server to put the information required by a DHCP client in the response packet
to the client. The four sub-options of option 184 mainly carry information about
voice. The following lists the sub-options and the carried information:
Sub-option 1: IP address of the network call processor (NCP-IP).
■
Sub-option 2: IP address of the alternate server (AS-IP).
■
Sub-option 3: Voice VLAN configuration.
■
Sub-option 4: Fail-over call routing.
■
Meanings of the sub-options for option 184
NCP-IP
■
The NCP-IP sub-option carries the IP address of the network call processor (NCP).
When used in option 184, this sub-option must be the first sub-option, that is,
sub-option 1.
The IP address of the NCP server carried by sub-option 1 of option 184 is intended
for identifying the server acting as the network call controller and the server used
for application downloading.
AS-IP
■
The AS-IP sub-option carries the IP address of the alternate server (AS), and is the
second sub-option of option 184, that is, sub-option 2. The AS-IP sub-option takes
effect only when sub-option 1 (that is, the NCP-IP sub-option) is defined.
The alternate NCP server identified by sub-option 2 of option 184 acts as the
backup of the NCP server and is used only when the IP address carried by the
NCP-IP sub-option is unreachable or invalid.
Voice VLAN Configuration
■
The voice VLAN configuration sub-option carries the ID of the voice VLAN and the
flag indicating whether the voice VLAN identification function is enabled. This
sub-option is the third sub-option of option 184, that is, sub-option 3.
Command
system-view
dhcp server ping packets
number
dhcp server ping timeout
milliseconds
Description
-
Optional
By default, a DHCP server performs the
ping operation twice to test an IP
address.
Optional
The default timeout time is 500
milliseconds.