Alcatel-Lucent 7450 Configuration Manual page 208

Router Interface Commands
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 giaddr 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
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
circuit-id
Syntax circuit-id [ascii-tuple | ifindex | sap-id | vlan-ascii-tuple]
no circuit-id
Context config>router>if>dhcp>option
Description
When enabled, the router sends the interface index (If Index) in the circuit-id suboption of the DHCP
packet. The If Index of a router interface can be displayed using the command
show>router>interface>detail. This option specifies data that must be unique to the router that is
relaying the circuit.
If disabled, the circuit-id suboption of the DHCP packet will be left empty.
The no form of this command returns the system to the default.
Default
circuit-id
Parameters
ascii-tuple — Specifies that the ASCII-encoded concatenated tuple will be used which consists of
ifindex — Specifies that the interface index will be used. The If Index of a router interface can be
sap-id — Specifies that the SAP ID will be used.
vlan-ascii-tuple — Specifies that the format will include VLAN-id and dot1p bits in addition to what
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Option 82 field from the router. In the downstream direction (towards the user) the Option 82
field is stripped (in accordance with RFC 3046).
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.
the access-node-identifier, service-id, and interface-name, separated by "|".
displayed using the command show>router>interface>detail.
is included in ascii-tuple already. The format is supported on dot1q and qinq ports only. Thus,
7450 ESS Router Configuration Guide