DHCP S
NOOPING
C
OMMANDS
22-11
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 22-13), DHCP messages received on
an untrusted interface (as specified by the
no ip dhcp snooping trust
command, page 22-17) 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, and
static entries configured in the DHCP snooping table.
• 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.
Содержание 7824M/FSW - annexe 1
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Страница 24: ...TABLE OF CONTENTS xxiv ...
Страница 28: ...TABLES xxviii ...
Страница 32: ...FIGURES xxxii Figure 16 3 DNS Cache 16 7 ...
Страница 34: ...GETTING STARTED ...
Страница 46: ...SYSTEM DEFAULTS 1 12 ...
Страница 62: ...SWITCH MANAGEMENT ...
Страница 74: ...CONFIGURING THE SWITCH 3 12 ...
Страница 112: ...BASIC MANAGEMENT TASKS 4 38 ...
Страница 168: ...USER AUTHENTICATION 6 30 ...
Страница 223: ...SHOWING PORT STATISTICS 9 33 Figure 9 12 Port Statistics ...
Страница 230: ...ADDRESS TABLE SETTINGS 10 6 ...
Страница 304: ...CLASS OF SERVICE 13 16 ...
Страница 316: ...QUALITY OF SERVICE 14 12 ...
Страница 338: ...MULTICAST FILTERING 15 22 ...
Страница 346: ...DOMAIN NAME SERVICE 16 8 ...
Страница 348: ...COMMAND LINE INTERFACE IP Interface Commands 35 1 ...
Страница 362: ...OVERVIEW OF COMMAND LINE INTERFACE 17 14 ...
Страница 426: ...SYSTEM MANAGEMENT COMMANDS 19 56 Example Console show calendar 15 12 34 February 1 2002 Console ...
Страница 494: ...USER AUTHENTICATION COMMANDS 21 48 ...
Страница 514: ...CLIENT SECURITY COMMANDS 22 20 ...
Страница 540: ...ACCESS CONTROL LIST COMMANDS 23 26 ...
Страница 558: ...INTERFACE COMMANDS 24 18 ...
Страница 576: ...MIRROR PORT COMMANDS 26 4 ...
Страница 582: ...RATE LIMIT COMMANDS 27 6 ...
Страница 616: ...SPANNING TREE COMMANDS 29 28 ...
Страница 644: ...VLAN COMMANDS 30 28 ...
Страница 664: ...CLASS OF SERVICE COMMANDS 31 20 ...
Страница 678: ...QUALITY OF SERVICE COMMANDS 32 14 ...
Страница 720: ...APPENDICES ...
Страница 726: ...SOFTWARE SPECIFICATIONS A 6 ...
Страница 730: ...TROUBLESHOOTING B 4 ...
Страница 746: ...INDEX Index 6 ...
Страница 747: ......