Ip Dhcp Relay Information Option - Edge-Core ECS4120-28F Reference Manual

ip dhcp relay
information option
This command enables DHCP Option 82 information relay, and specifies the frame
format to use for the remote-id when Option 82 information is generated by the
switch. Use the no form of this command to disable this feature.
Syntax

ip dhcp relay information option

[encode no-subtype]
[vlan vlan-list | add vlan-list | remove vlan-list]
no ip dhcp rely information option [encode no-subtype]
encode no-subtype - Disables use of sub-type and sub-length fields in circuit-
ID (CID) and remote-ID (RID) in Option 82 information.
vlan vlan-list - Enables DHCP Option 82 information relay for the specified
VLAN or list of VLANs. Separate nonconsecutive VLANs with a comma and
no spaces; or use a hyphen to designate a range of VLANs. (Range: 1-4094)
add vlan-list - Enables DHCP Option 82 information relay for the specified
VLANs to an existing list of Option 82 enabled VLANs.
remove vlan-list - Disables DHCP Option 82 information relay for the
specified VLANs within an existing list of Option 82 enabled VLANs
Default Setting
Option 82: Disabled
CID/RID sub-type: Enabled
Command Mode
Global Configuration
Usage Guidelines
◆
Using this command with or without any keywords will enable DHCP Option 82
information relay. You must also specify the IP address for at least one active
DHCP server (with the
DHCP relay agent will not be able to forward client requests to a DHCP server.
◆
DHCP provides a relay agent information option for sending information about
its DHCP clients or the relay agent itself to the DHCP server. Also known as
DHCP Option 82, it allows compatible DHCP servers to use this information
when assigning IP addresses, or to set other services or policies for clients.
◆
When Option 82 is enabled, the requesting client (or an intermediate relay
agent that has used the information fields to describe itself ) can be identified in
the DHCP request packets forwarded by the switch and in reply packets sent
back from the DHCP server.
◆
By default, the relay agent also fills in the Option 82 circuit-id field with
information indicating the local interface over which the switch received the
DHCP client request, including the VLAN ID, stack unit, and port. This allows
DHCP client-server exchange messages to be forwarded between the server
and client without having to flood them onto the entire VLAN.
ip dhcp relay server command). Otherwise, the switch's
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Chapter 29
| DHCP Commands
DHCP Relay Option 82