(Optional) Configuring User-defined Options
Context
Vendors can define DHCP options. The device can function as a DHCP server to allocate vendor-defined network parameters to clients. When the device functions as a DHCP Server, it can allocate network parameters to clients based on the Option fields in the requests from the clients.
The device inserts an option configured using the dhcp server option (based on an interface address pool) or option (based on a global address pool) command into DHCP Reply messages to be sent to a client only when the client requests this option.
When a global address pool is used to allocate network parameters, configuration commands are different for dynamic and static DHCP clients.
Procedure
- Configure user-defined options based on an interface address pool.
- Configure user-defined options.
dhcp server option code [ sub-option sub-code ] { ascii ascii-string | hex hex-string | cipher cipher-string | ip-address ip-address &<1-8> }
By default, no user-defined option is configured.
If an option carries a password, the option code in ascii or hex type is insecure. Therefore, you are advised to set the option code type to cipher. For security purposes, use a password that is at least six characters long and contains at least two types of the following: lowercase letters, uppercase letters, digits, and special characters.
After an option is configured, the device inserts the option into DHCP Reply messages to be sent to clients only when the clients request this option.
Not all options can be configured using the preceding command. The following table lists the options and their commands.Table 1 Commands for configuring options Option
Configuration Command
Description
Option1
mask-length in the ip address ip-address { mask | mask-length } command
Subnet mask
Option3
ip-address in the ip address ip-address { mask | mask-length } command
Gateway address
Option6
dhcp server dns-list ip-address &<1-8>
DNS server IP address
Option15
dhcp server domain-name (interface view) domain-name
Domain name
Option44
dhcp server nbns-list ip-address &<1-8>
NetBIOS server IP address
Option46
dhcp server netbios-type { b-node | h-node | m-node | p-node }
NetBIOS node type
Option50
N/A
Requested IP address
Option51
dhcp server lease { day day [ hour hour [ minute minute ] ] | unlimited }
IP address lease
Option52
N/A
Additional option
Option53
N/A
DHCP message type
Option54
N/A
Server identifier
Option55
N/A
Parameter request list
Option57
N/A
Maximum length of a DHCP message
Option58
N/A
Lease renewal time (T1), which is 50% of the lease time
Option59
N/A
Lease renewal time (T2), which is 87.5% of the lease time
Option61
N/A
Client identifier
Option82
N/A
Relay agent information
Option120
dhcp server sip-server { ip-address ip-address &<1-2> | list domain-name &<1-2> }
SIP server IP address
Option121
dhcp server option121 ip-address { ip-address mask-length gateway-address } &<1-8>
A group of classless routes
Option184
dhcp server option184 { as-ip ip-address | fail-over ip-address dialer-string | ncp-ip ip-address | voice-vlan vlan-id }
Voice parameters
- Configure user-defined options.
- Configure user-defined options based on a global address pool.
In the global address pool view:
- Enter the system view.
system-view (Optional) Enable the DHCP server to trust Option 82.
dhcp server trust option82
By default, the device is enabled to trust Option 82.
- Enter the global address pool view.
ip pool ip-pool-name
Configure user-defined options.
option code [ sub-option sub-code ] { ascii ascii-string | hex hex-string | cipher cipher-string | ip-address ip-address &<1-8> }
By default, no user-defined option is configured.
If an option carries a password, the option code in ascii or hex type is insecure. Therefore, you are advised to set the option code type to cipher. For security purposes, use a password that is at least six characters long and contains at least two types of the following: lowercase letters, uppercase letters, digits, and special characters.
Not all options can be configured using the preceding command. The following table lists the options and their commands.Table 2 Commands for configuring options Option
Configuration Command
Description
Option1
mask-length in the network (IP address pool view) ip-address [ mask { mask | mask-length } ]
Subnet mask
Option3
gateway-list ip-address &<1-8>
Gateway address
Option6
dns-list ip-address &<1-8>
DNS server IP address
Option15
domain-name domain-name
Domain name suffix
Option44
nbns-list ip-address &<1-8>
NetBIOS server IP address
Option46
netbios-type { b-node | h-node | m-node | p-node }
NetBIOS node type
Option50
N/A
Requested IP address
Option51
lease { day day [ hour hour [ minute minute ] ] | unlimited }
IP address lease
Option52
N/A
Additional option
Option53
N/A
DHCP message type
Option54
N/A
Server identifier
Option55
N/A
Parameter request list
Option57
N/A
Maximum length of a DHCP message
Option58
N/A
Lease renewal time (T1), which is 50% of the lease time
Option59
N/A
Lease renewal time (T2), which is 87.5% of the lease time
Option61
N/A
Client identifier
Option82
N/A
Relay agent information
Option120
sip-server { ip-address ip-address &<1-2> | list domain-name &<1-2> }
SIP server IP address
Option121
option121 ip-address { ip-address mask-length gateway-address } &<1-8>
A group of classless routes
Option184
option184 { as-ip ip-address | fail-over ip-address dialer-string | ncp-ip ip-address | voice-vlan vlan-id }
Voice parameters
- Enter the system view.