IP Router Configuration Command Reference
218 Router Configuration Guide
option
Syntax [no] option
Context config>router>if>dhcp
Description This command enables DHCP Option 82 (Relay Agent Information Option) parameters processing and
enters the context for configuring Option 82 sub-options.
The no form of this command returns the system to the default.
Default no option
action
Syntax action {replace | drop | keep}
no action
Context config>router>if>dhcp>option
Description This command configures the processing required when the SR-Series router receives a DHCP request
that already has a Relay Agent Information Option (Option 82) field in the packet.
The no form of this command returns the system to the default value.
Default Per RFC 3046, DHCP Relay Agent Information Option, section 2.1.1, Reforwarded DHCP
requests, the default is to keep the existing information intact. The exception to this is if the GI address
of the received packet is the same as the ingress address on the router. In that case the packet is dropped
and an error is logged.
Parameters replace — In the upstream direction (from the user), the existing Option 82 field is replaced with
the Option 82 field from the router. In the downstream direction (towards the user) the Option
82 field is stripped (in accordance with RFC 3046).
drop — The packet is dropped, and an error is logged.
keep — The existing information is kept in the packet and the router does not add any additional
information. In the downstream direction the Option 82 field is not stripped and is sent on
towards the client.
The behavior is slightly different in case of Vendor Specific Options (VSOs). When the keep
parameter is specified, the router will insert his own VSO into the Option 82 field. This will
only be done when the incoming message has already an Option 82 field.
If no Option 82 field is present, the router will not create the Option 82 field. In this in that
case, no VSO will be added to the message.
circuit-id
Syntax circuit-id [ascii-tuple | ifindex | sap-id | vlan-ascii-tuple]
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