Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 273)

Brocade 6910 Ethernet Access Switch Configuration Guide 223
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DHCP Snooping
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• Set all ports connected to DHCP servers within the local network or fire wall to trusted, and all
other ports outside the local network or fire wall to untrusted.
• When DHCP snooping is enabled globally using the ip dhcp snooping command, and enabled
on a VLAN with ip dhcp snooping vlan command, DHCP packet filtering will be performed on
any untrusted ports within the VLAN according to the default status, or as specifically
configured for an interface with the
no ip dhcp snooping trust command.
• When an untrusted port is changed to a trusted port, all the dynamic DHCP snooping bindings
associated with this port are removed.
• Additional considerations when the switch itself is a DHCP client – The port(s) through which it
submits a client request to the DHCP server must be configured as trusted.
Example
This example sets port 5 to untrusted.
Console(config)#interface ethernet 1/5
Console(config-if)#no ip dhcp snooping trust
Console(config-if)#
Related Commands
ip dhcp snooping (216)
ip dhcp snooping vlan (220)
clear ip dhcp snooping binding
This command clears DHCP snooping binding table entries from RAM. Use this command without
any optional keywords to clear all entries from the binding table.
Syntax
clear ip dhcp snooping binding [mac-address vlan vlan-id]
mac-address - Specifies a MAC address entry.
(Format: xx-xx-xx-xx-xx-xx)
vlan-id - ID of a configured VLAN (Range: 1-4093)
Command Mode
Privileged Exec
Example
Console(config)#clear ip dhcp snooping binding 11-22-33-44-55-66 vlan 1
Console(config)#
clear ip dhcp snooping database flash
This command removes all dynamically learned snooping entries from flash memory.
Command Mode
Privileged Exec