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Command Line Interface
4-228
4
ip dhcp snooping
This command enables DHCP snooping globally. Use the no form to restore the
default setting.
Syntax
[
no
]
ip dhcp snooping
Default Setting
Disabled
Command Mode
Global Configuration
Command Usage
• Network traffic may be disrupted when malicious DHCP messages are
received from an outside source. DHCP snooping is used to filter DHCP
messages received on an unsecure interface from outside the network or
firewall. When DHCP snooping is enabled globally by this command, and
enabled on a VLAN interface by the
ip dhcp snooping vlan
command (page
4-230
), DHCP messages received on an untrusted interface (as specified by
the
no ip dhcp snooping trust
command, page
4-230
) from a device not
listed in the DHCP snooping table will be dropped.
• When enabled, DHCP messages entering an untrusted interface are filtered
based upon dynamic entries learned via DHCP snooping.
• Table entries are only learned for untrusted interfaces. Each entry includes a
MAC address, IP address, lease time, entry type (Dynamic-DHCP-Binding,
Static-DHCP-Binding), VLAN identifier, and port identifier.
• When DHCP snooping is enabled, the rate limit for the number of DHCP
messages that can be processed by the switch is 100 packets per second.
Any DHCP packets in excess of this limit are dropped.
• Filtering rules are implemented as follows:
- If the global DHCP snooping is disabled, all DHCP packets are
forwarded.
- If DHCP snooping is enabled globally, and also enabled on the VLAN
where the DHCP packet is received, all DHCP packets are forwarded for
ip dhcp snooping
information policy
Enables DNS-based host name-to-address translation
GC
4-233
ip dhcp snooping
database flash
Displays the static host name-to-address mapping table
GC
4-233
show ip dhcp snooping
Displays the configuration for DNS services
PE
4-234
show ip dhcp snooping
binding
Displays entries in the DNS cache
PE
4-234
Table 4-78. DHCP Snooping Commands
Command
Function
Mode
Page
Summary of Contents for 8124PL2
Page 1: ...MANAGEMENT GUIDE TigerSwitchTM 10 100 1000 24 Port Managed Switch with PoE SMC8124PL2 ...
Page 2: ......
Page 20: ...xvi Contents ...
Page 27: ...xxiii Figures ...
Page 35: ...Introduction 1 8 1 ...
Page 45: ...Initial Configuration 2 10 2 ...
Page 148: ...Port Configuration 3 103 Figure 3 61 Displaying Etherlike and RMON Statistics ...
Page 473: ...Command Line Interface 4 240 4 ...
Page 477: ...Software Specifications A 4 A ...
Page 489: ...Index Index 4 menu list 3 3 panel display 3 3 ...
Page 490: ......