
C
HAPTER
14
| Security Measures
DHCP Snooping
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the DHCP client request, including the port and VLAN ID. This allows
DHCP client-server exchange messages to be forwarded between the
server and client without having to flood them to the entire VLAN.
If DHCP Snooping Information Option 82 is enabled on the switch,
information may be inserted into a DHCP request packet received over
any VLAN (depending on DHCP snooping filtering rules). The
information inserted into the relayed packets includes the circuit-id and
remote-id, as well as the gateway Internet address.
When the switch receives DHCP packets from clients that already
include DHCP Option 82 information, the switch can be configured to
set the action policy for these packets. The switch can either drop the
DHCP packets, keep the existing information, or replace it with the
switch’s relay information.
DHCP S
NOOPING
C
ONFIGURATION
Use the IP Service > DHCP > Snooping (Configure Global) page to enable
DHCP Snooping globally on the switch, or to configure MAC Address
Verification.
CLI R
EFERENCES
P
ARAMETERS
These parameters are displayed:
DHCP Snooping Status –
Enables DHCP snooping globally.
(Default: Disabled)
DHCP Snooping MAC-Address Verification
– Enables or disables
MAC address verification. If the source MAC address in the Ethernet
header of the packet is not same as the client's hardware address in the
DHCP packet, the packet is dropped. (Default: Enabled)
DHCP Snooping Information Option Status
– Enables or disables
DHCP Option 82 information relay. (Default: Disabled)
DHCP Snooping Information Option Policy
– Specifies how to
handle DHCP client request packets which already contain Option 82
information.
Drop
– Drops the client’s request packet instead of relaying it.
Keep
– Retains the Option 82 information in the client request, and
forwards the packets to trusted ports.
Replace
– Replaces the Option 82 information circuit-id and
remote-id fields in the client’s request with information about the
relay agent itself, inserts the relay agent’s address (when DHCP
snooping is enabled), and forwards the packets to trusted ports.
(This is the default policy.)
Summary of Contents for DG-FS4526E
Page 4: ...ABOUT THIS GUIDE 4...
Page 34: ...CONTENTS 34...
Page 50: ...TABLES 50...
Page 52: ...SECTION I Getting Started 52...
Page 62: ...CHAPTER 1 Introduction System Defaults 62...
Page 80: ...CHAPTER 2 Initial Switch Configuration Managing System Files 80...
Page 82: ...SECTION II Web Configuration 82...
Page 100: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 100...
Page 128: ...CHAPTER 4 Basic Management Tasks Resetting the System 128...
Page 166: ...CHAPTER 5 Interface Configuration VLAN Trunking 166...
Page 198: ...CHAPTER 6 VLAN Configuration Configuring VLAN Mirroring 198...
Page 516: ...CHAPTER 17 IP Services Displaying the DNS Cache 516...
Page 562: ...CHAPTER 19 Using the Command Line Interface CLI Command Groups 562...
Page 652: ...CHAPTER 22 SNMP Commands 652...
Page 660: ...CHAPTER 23 Remote Monitoring Commands 660...
Page 714: ...CHAPTER 24 Authentication Commands Management IP Filter 714...
Page 802: ...CHAPTER 27 Interface Commands 802...
Page 824: ...CHAPTER 29 Port Mirroring Commands RSPAN Mirroring Commands 824...
Page 846: ...CHAPTER 32 Address Table Commands 846...
Page 874: ...CHAPTER 33 Spanning Tree Commands 874...
Page 886: ...CHAPTER 34 ERPS Commands 886...
Page 928: ...CHAPTER 35 VLAN Commands Configuring Voice VLANs 928...
Page 942: ...CHAPTER 36 Class of Service Commands Priority Commands Layer 3 and 4 942...
Page 998: ...CHAPTER 38 Multicast Filtering Commands Multicast VLAN Registration 998...
Page 1022: ...CHAPTER 39 LLDP Commands 1022...
Page 1064: ...CHAPTER 40 CFM Commands 1064...
Page 1084: ...CHAPTER 42 Domain Name Service Commands 1084...
Page 1090: ...CHAPTER 43 DHCP Commands DHCP Client 1090...
Page 1122: ...CHAPTER 44 IP Interface Commands IPv6 Interface 1122...
Page 1124: ...SECTION IV Appendices 1124...
Page 1130: ...APPENDIX A Software Specifications Management Information Bases 1130...
Page 1152: ...COMMAND LIST 1152...
Page 1161: ......
Page 1162: ...DG FS4526E 042012 HW R01...