C
HAPTER
24
| General Security Measures
DHCPv4 Snooping
– 906 –
ip dhcp snooping
This command enables DHCP snooping globally. Use the
no
form to restore
the default setting.
S
YNTAX
[
no
]
ip dhcp snooping
D
EFAULT
S
ETTING
Disabled
C
OMMAND
M
ODE
Global Configuration
C
OMMAND
U
SAGE
◆
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 fire wall. When DHCP snooping is enabled globally by this command,
and enabled on a VLAN interface by the
ip dhcp snooping vlan
command, DHCP messages received on an untrusted interface (as
specified by the
no
ip dhcp snooping trust
command) 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 trusted interfaces. Each entry
includes a MAC address, IP address, lease time, 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 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 a
trusted
port. If the received packet is a DHCP ACK message, a
dynamic DHCP snooping entry is also added to the binding table.
ip dhcp snooping database
flash
Writes all dynamically learned snooping entries to
flash memory
PE
show ip dhcp snooping
Shows the DHCP snooping configuration settings
PE
show ip dhcp snooping
binding
Shows the DHCP snooping binding table entries
PE
Table 92: DHCP Snooping Commands
(Continued)
Command
Function
Mode
Содержание ECS3510-10PD
Страница 1: ...Management Guide www edge core com 10 Port Layer 2 Fast Ethernet Switch...
Страница 2: ......
Страница 4: ......
Страница 48: ...CONTENTS 48...
Страница 68: ...SECTION I Getting Started 68...
Страница 78: ...CHAPTER 1 Introduction System Defaults 78...
Страница 96: ...CHAPTER 2 Initial Switch Configuration Managing System Files 96...
Страница 98: ...SECTION II Web Configuration 98...
Страница 118: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 118...
Страница 150: ...CHAPTER 4 Basic Management Tasks Resetting the System 150...
Страница 196: ...CHAPTER 5 Interface Configuration VLAN Trunking 196 Figure 66 Configuring VLAN Trunking...
Страница 238: ...CHAPTER 7 Address Table Settings Configuring MAC Address Mirroring 238...
Страница 264: ...CHAPTER 8 Spanning Tree Algorithm Configuring Interface Settings for MSTP 264...
Страница 274: ...CHAPTER 9 Congestion Control Automatic Traffic Control 274...
Страница 288: ...CHAPTER 10 Class of Service Layer 3 4 Priority Settings 288...
Страница 304: ...CHAPTER 11 Quality of Service Attaching a Policy Map to a Port 304...
Страница 423: ...CHAPTER 13 Security Measures DHCP Snooping 423 Figure 229 Displaying the Binding Table for DHCP Snooping...
Страница 424: ...CHAPTER 13 Security Measures DHCP Snooping 424...
Страница 568: ...CHAPTER 14 Basic Administration Protocols OAM Configuration 568...
Страница 596: ...CHAPTER 15 IP Configuration Setting the Switch s IP Address IP Version 6 596...
Страница 614: ...CHAPTER 1 IP Services Configuring the PPPoE Intermediate Agent 614...
Страница 784: ...CHAPTER 20 System Management Commands Powered Device 784...
Страница 814: ...CHAPTER 22 Remote Monitoring Commands 814...
Страница 1008: ...CHAPTER 26 Interface Commands Power Savings 1008...
Страница 1022: ...CHAPTER 27 Link Aggregation Commands Trunk Status Display Commands 1022...
Страница 1052: ...CHAPTER 29 Congestion Control Commands Automatic Traffic Control Commands 1052...
Страница 1064: ...CHAPTER 31 UniDirectional Link Detection Commands 1064...
Страница 1070: ...CHAPTER 32 Address Table Commands 1070...
Страница 1130: ...CHAPTER 34 ERPS Commands 1130...
Страница 1172: ...CHAPTER 35 VLAN Commands Configuring Voice VLANs 1172...
Страница 1186: ...CHAPTER 36 Class of Service Commands Priority Commands Layer 3 and 4 1186...
Страница 1302: ...CHAPTER 38 Multicast Filtering Commands MVR for IPv6 1302...
Страница 1368: ...CHAPTER 40 CFM Commands Delay Measure Operations 1368...
Страница 1390: ...CHAPTER 42 Domain Name Service Commands 1390...
Страница 1448: ...CHAPTER 44 IP Interface Commands ND Snooping 1448...
Страница 1450: ...SECTION IV Appendices 1450...
Страница 1455: ...APPENDIX A Software Specifications Management Information Bases 1455 UDP MIB RFC 2013...
Страница 1456: ...APPENDIX A Software Specifications Management Information Bases 1456...
Страница 1464: ...APPENDIX D Compliances and Safety Statements CE Mark Declaration of Conformance for EMI and Safety EEC 1464...
Страница 1482: ...COMMAND LIST 1482...
Страница 1493: ......
Страница 1494: ...ECS3510 10PD E032014 ST R03 149100000179A...