More Information About HW-Dhcp-Option (187)
Format of HW-Dhcp-Option (187)
The HW-Dhcp-Option (187) attribute delivered by a RADIUS server must use the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2
+---------------+---------------+---------------------------------+
| Type | Length | Option Type |
+---------------+---------------+---------------------------------+
| value
+-----------------
Option Type: 2 bytes
Value: option value
HW-Dhcp-Option (187) Attribute Rules
- Rule1: A maximum of eight options can be delivered. After parsing eight valid options, subsequent ones are ignored.
Rule2: If a duplicate option is delivered, it replaces the one previously delivered. Option121 is an exception because this option carries routing information and can be delivered multiple times.
Example for rules 1 and 2: If eight options are delivered with the first and eighth options having the same number, the eighth option replaces the first option. That is to say, there are only seven options in effect, and the ninth option (if there is the ninth option) can be parsed successfully.
If eight unique options have been delivered and the ninth option is the same as the first option, the ninth option is not parsed.
Rule3: The following options cannot be delivered.
Option Code
Description
Reason
0
Byte aligning
This option for byte aligning is not a normal option.
1
Subnet mask
A subnet mask belongs to an address pool and therefore should not be delivered.
3
Gateway
A gateway belongs to an address pool configuration. DHCP users do not support gateway option delivery.
12
Client host name
This option is sent by a DHCP client to a BAS device.
53
Type of a DHCP message
This option indicates the type of a DHCP message and cannot be delivered.
54
Server identifier
This option is the gateway address for DHCP clients and encapsulated in Offer and ACK messages. This option code is not supported currently.
55
Request parameter list
This option is sent by a DHCP client to a BAS device.
61
Client identifier
This option is sent by a DHCP client to a BAS device.
64
Network information server (NIS)+ domain name
This option identifies a DHCP client.
77
User Class Option
This option is sent by a DHCP client to a BAS device.
82
Relay information
This option is sent by a DHCP client to a BAS device.
Rule4: The following options are replaced by RADIUS attributes before being delivered.
Option Code
Description
Radius Attribute Number
Attribute Name
6
Domain Server
26-135
HW-Client-Primary-DNS
26-136
HW-Client-Secondary-DNS
43
Vendor Specific
26-156
HW-DHCPV4-Option43
44
NETBIOS Name Srv
26-75
HW-Ascend-Client-Primary-WINS
26-76
HW-Ascend-Client-Second-WIN
51
Address Time
26-74
HW-Lease-Time
58
Renewal Time
26-35
HW-Renewal-Time
59
Rebinding Time
26-36
HW-Rebinding-Time
120
DHCP_OPT120
26-32
RD_hw_SIP_Server
121
Classless Static Route Option
26-155
HW-DHCPv4-Option121
- Rule5: The preceding RADIUS attributes that are converted from the options have the same priorities as those directly delivered by a RADIUS server. Except for Option121, those delivered later take effect.
- Rule6: A maximum of 24 Option121s can be delivered. If the total number of routes delivered by two attributes is less than 24, Option121 can be continually delivered. If there are more than 24 routes, a failure is returned, and users cannot log in.
- Rule7: Option6 and Option44 can be parsed as either RADIUS attribute numbers 26-135 and 26-136, respectively, or 26-75 and 26-76, respectively. A maximum of two IP addresses can take effect in the format of ULONG. The first two IP addresses are delivered after being converted to the corresponding RADIUS attributes.
- Rule8: To parse an option, a RADIUS server first determines whether the option can be delivered and whether the option length meets the requirement. If it cannot be delivered or its length does not meet the requirement, the RADIUS server ignores this option and continues its polling. After the first round of determination, if the RADIUS server finds that this option must be converted to a RADIUS attribute before being delivered, it converts this option to the desired RADIUS attribute. If this attribute fails to be parsed, users fail to log in.
- Rule 9: To trigger a user that goes offline unexpectedly to go online again, the options sent to the RADIUS server can only be the Option 12,61,60,82,77 stored in the backup table of the unexpected logout.