Dhcpv4 Relay Agent Information - ZyXEL Communications GS1920v2 Series User Manual

The Switch can be configured as a global DHCP relay. This means that the Switch forwards all DHCP
requests from all domains to the same DHCP server. You can also configure the Switch to relay DHCP
information based on the VLAN membership of the DHCP clients.
37.4.1 DHC Pv4 Re la y Ag e nt Info rm a tio n
The Switch can add information about the source of client DHCP requests that it relays to a DHCP server
by adding
Re la y Ag e nt Info rm a tio n
The DHCP server can then provide an IP address based on this information. Please refer to RFC 3046 for
more details.
The DHCP
Re la y Ag e nt Info rm a tio n
field) to DHCP requests. The
82
the Switch relays to a DHCP server.
Re la y Ag e nt Info rm a tio n
change the
The following describes the DHCP relay agent information that the Switch sends to the DHCP server:
Table 153 Relay Agent Information
FIEL D L ABEL S
Slot ID
Port ID
VLAN ID
Information
37.4.1.1 DHC Pv4 Re la y Ag e nt Info rm a tio n Fo rm a t
A DHCP Relay Agent Information option has the following format.
Table 154 DHCP Relay Agent Information Option Format
Code
(82)
i1, i2 and iN are DHCP relay agent sub-options, which contain additional information about the DHCP
client. You need to define at least one sub-option.
37.4.1.2 Sub - O ptio n Fo rm a t
There are two types of sub-option: "Agent Circuit ID Sub-option" and "Agent Remote ID Sub-option".
They have the following formats.
Table 155 DHCP Relay Agent Circuit ID Sub-option Format
SubOpt Code
1
(1 byte)
. This helps provide authentication about the source of the requests.
feature adds an Agent Information field (also known as the
O ptio n 82
can include the
in
Syste m Na m e Ba sic Se tting s
DESC RIPT IO N
(1 byte) This value is always 0 for stand-alone switches.
(1 byte) This is the port that the DHCP client is connected to.
(2 bytes) This is the VLAN that the port belongs to.
(up to 64 bytes) This optional, read-only field is set according to system name set in
Se tting s > G e ne ra l Se tup
Length i1
(N)
Length
N Slot ID, Port ID, VLAN ID, System Name or String
(1 byte)
GS1920v2 Series User's Guide
Chapter 37 DHCP
field is in the DHCP headers of client DHCP request frames that
of the Switch if you select this option. You can
Syste m Na m e
> .
G e ne ra l Se tup
.
i2
...
Value
325
iN
O ptio n
Ba sic