LevelOne GTL-2691 - Manual (Page 949)

C HAPTER 29 | General Security Measures
DHCP Snooping
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ip dhcp snooping
database flash
This command writes all dynamically learned snooping entries to flash
memory.
C OMMAND M ODE
Privileged Exec
C OMMAND U SAGE
This command can be used to store the currently learned dynamic DHCP
snooping entries to flash memory. These entries will be restored to the
snooping table when the switch is reset. However, note that the lease time
shown for a dynamic entry that has been restored from flash memory will
no longer be valid.
E XAMPLE
Console(config)#ip dhcp snooping database flash
Console(config)#
ip dhcp snooping
information option
This command enables the DHCP Option 82 information relay for the
switch. Use the no form without any keywords to disable this function, the
no form with the encode no-subtype keyword to enable use of sub-type
and sub-length in CID/RID fields.
S YNTAX
[no] ip dhcp snooping 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.
D EFAULT S ETTING
Option 82: Disabled
CID/RID sub-type: Enabled
C OMMAND M ODE
Global Configuration
C OMMAND U SAGE
◆ DHCP provides a relay mechanism for sending information about the
switch and its DHCP clients to the DHCP server. Known as DHCP Option
82, it allows compatible DHCP servers to use the information when
assigning IP addresses, or to set other services or policies for clients.
◆ When the DHCP Snooping Information Option 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.
◆ When the DHCP Snooping Information Option is enabled, clients can be
identified by the switch port to which they are connected rather than