Enabling and Disabling Insertion of Option 82 Information
You can enable or disable support for the DHCP relay agent information option (option 82) in packets destined for a DHCP server. To enable support for the DHCP relay agent information option you use the relay-option-82 statement.
You can configure option 82 support globally or for a named group of interfaces.
To enable support for DHCP relay agent information option 82:
- Specify that you want to configure option 82 support.
- [edit forwarding-options dhcp-relay]
- user@host# edit relay-option-82
- Insert the option 82 information in DHCP packets.
- (Optional) Include an option 82 prefix with the base option 82 information.
- (Optional) To restore the default behavior (option
82 information is not inserted into DHCP packets), do not include
any subordinate statements.
- [edit forwarding-options dhcp-relay]
- user@host# set relay-option-82
This topic includes the following sections:
Configuring Agent-Circuit-Id Information
You use the relay-option-82 statement to enable insertion of option 82 information in DHCP packets. You must also specify at least the circuit-id statement to include the agent-circuit-id suboption (suboption 1) of the DHCP relay agent information option.
If you specify the circuit-id statement, the format of the agent-circuit id information for Fast Ethernet (fe) or Gigabit Ethernet (ge) interfaces is one of the following, depending on your network configuration:
- For Fast Ethernet or Gigabit Ethernet interfaces that
do not use virtual local area networks (VLANs) or stacked VLANs (S-VLANs):
- (fe | ge)-fpc/pic/port
- For Fast Ethernet or Gigabit Ethernet interfaces that
use VLANs:
- (fe | ge)-fpc/pic/port:vlan-id
- For Fast Ethernet or Gigabit Ethernet interfaces that
use S-VLANs:
- (fe | ge)-fpc/pic/port:svlan-id-vlan-id
To enable insertion of option 82 information:
- Specify that you want to configure option 82 support.
- [edit forwarding-options dhcp-relay]
- user@host# edit relay-option-82
- Specify insertion of the agent-circuit
id.
- [edit forwarding-options dhcp-relay relay-option-82]
- user@host# set circuit-id
Configuring an Option 82 Prefix
You can include an optional prefix to the base option 82 information in DHCP packets destined for a DHCP server.
The prefix is separated from the option 82 agent-circuit-id information by a colon (:), and can include any combination of the host-name, logical-system-name, and routing-instance-name options. The DHCP relay agent obtains the values for the host-name, logical-system-name, and routing-instance-name as follows:
- If you include the host-name option, the DHCP relay agent uses the hostname of the router configured with the host-name statement at the [edit system] hierarchy level.
- If you include the logical-system-name option, the DHCP relay agent uses the logical system name configured with the logical-system statement at the [edit logical-system] hierarchy level.
- If you include the routing-instance-name option, the DHCP relay agent uses the routing instance name configured with the routing-instance statement at the [edit routing-instances] hierarchy level or at the [edit logical-system logical-system-name routing-instances] hierarchy level.
If you include the hostname and either or both of the logical system name and the routing instance name in the prefix, the hostname is followed by a forward slash (/). If you include both the logical system name and the routing instance name in the prefix, these values are separated by a semicolon (;).
The following examples show several possible formats for the agent-circuit-id information when you specify the prefix statement for Fast Ethernet (fe) or Gigabit Ethernet (ge) interfaces with S-VLANs.
- If you include only the hostname in the prefix for Fast
Ethernet or Gigabit Ethernet interfaces with S-VLANs:
- hostname:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
- If you include only the logical system name in the prefix
for Fast Ethernet or Gigabit Ethernet interfaces with S-VLANs:
- logical-system-name:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
- If you include only the routing instance name in the prefix
for Fast Ethernet or Gigabit Ethernet interfaces with S-VLANs:
- routing-instance-name:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
- If you include both the hostname and the logical system
name in the prefix for Fast Ethernet or Gigabit Ethernet interfaces
with S-VLANs:
- host-name/logical-system-name:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
- If you include both the logical system name and the routing
instance name in the prefix for Fast Ethernet or Gigabit Ethernet
interfaces with S-VLANs:
- logical-system-name;routing-instance-name:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
- If you include the hostname, logical system name, and
routing instance name in the prefix for Fast Ethernet or Gigabit Ethernet
interfaces with S-VLANs:
- host-name/logical-system-name;routing-instance-name:(fe | ge)-fpc/pic/port:svlan-id-vlan-id
For Fast Ethernet or Gigabit Ethernet interfaces that use VLANs but not S-VLANs, only the vlan-id value appears in the agent-circuit-id format. For Fast Ethernet or Gigabit Ethernet interfaces that do not use VLANs or S-VLANs, neither the vlan-id value nor the svlan-id value appears.
To configure an optional prefix with the option 82 information:
- Specify that you want to configure option 82 support.
- [edit forwarding-options dhcp-relay]
- user@host# edit relay-option-82
- Specify insertion of the agent-circuit
id.
- [edit forwarding-options dhcp-relay relay-option-82]
- user@host# set circuit-id
- Specify that the prefix is included in
the option 82 information. In this example, the prefix includes the
hostname and logical system name
- [edit forwarding-options dhcp-relay relay-option-82]
- user@host# set circuit-id prefix host-name logical-system-name