BigIron RX Series Configuration Guide 1007
53-1002253-01
DHCP snooping
35
FIGURE 134 DHCP snooping at Work - on untrusted port
FIGURE 135 DHCP snooping at Work - on trusted port
System reboot and the binding database
To allow DAI and DHCP snooping to work smoothly across a system reboot, the binding database is
saved to a file in the system flash memory after the user issues the "reload" command. DHCP
learnt entries are written to the system flash memory before the router reboots. The flash file is
written and read only if DHCP snooping is enabled.
Configuring DHCP snooping
Configuring DHCP snooping consists of the following steps.
1. Enable DHCP snooping on a VLAN. Refer to “Enabling DHCP snooping on a VLAN” on
page 1008.
2. For ports that are connected to a DHCP server, change their trust setting to trusted. Refer to
“Enabling trust on a port” on page 1008.
The following shows the default settings of DHCP snooping.
Brocade Device
Trusted
Un trusted
reply packet
DHCP server
DHCP
Server
Snooping
DHCP
request packet
DHCP client
DHCP
Client
Brocade Device
DHCP server
reply packet
Trusted
Untrusted
DHCP
Server
DHCP
Snooping
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