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Dell PowerConnect 6248 Command Line Interface Guide - Page 649

Command Mode, User Guidelines, Example, arp purge

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Command Mode Global Configuration mode User Guidelines When an ARP entry reaches its maximum age, the system must decide whether to retain or delete the entry. If the entry has recently been used to forward data packets, the system will renew the entry by sending an ARP request to the neighbor. If the neighbor responds, the age of the ARP cache entry is reset to 0 without removing the entry from the hardware. Traffic to the host continues to be forwarded in hardware without interruption. If the entry is not being used to forward data packets, then the entry is deleted from the ARP cache, unless the dynamic renew option is enabled. If the dynamic renew option is enabled, the system sends an ARP request to renew the entry. When an entry is not renewed, it is removed from the hardware and subsequent data packets to the host trigger an ARP request. Traffic to the host is lost until the router receives an ARP reply from the host. Gateway entries, entries for a neighbor router, are always renewed. The dynamic renew option only applies to host entries. The disadvantage of enabling dynamic renew is that once an ARP cache entry is created, that cache entry continues to take space in the ARP cache as long as the neighbor continues to respond to ARP requests, even if no traffic is being forwarded to the neighbor. In a network where the number of potential neighbors is greater than the ARP cache capacity, enabling dynamic renew could prevent some neighbors from communicating because the ARP cache is full. Example console#configure console(config)#arp dynamicrenew console(config)#no arp dynamicrenew arp purge Use the arp purge command in Privileged EXEC mode to cause the specified IP address to be removed from the ARP cache. Only entries of type dynamic or gateway are affected by this command. ARP Commands 649

Section	Page
Contents	3
Command Groups	55
Introduction	55
Command Groups	55
Mode Types	60
Layer 2 Commands	61
AAA	61
ACL	62
Address Table	63
CDP Interoperability	64
DHCP l2 Relay	65
DHCP Snooping	65
Dynamic ARP Inspection	66
Ethernet Configuration	67
GVRP	68
IGMP Snooping	69
IGMP Snooping Querier	70
IP Addressing	71
IPv6 ACL	72
IPv6 MLD Snooping	72
IPv6 MLD Snooping Querier	73
LACP	73
Link Dependency	74
LLDP	74
Port Channel	76
Port Monitor	76
QoS	77
Radius	81
Spanning Tree	82
Switchport Voice	84
TACACS+	84
VLAN	85
Voice VLAN	87
802.1x	87
Layer 3 Commands	90
ARP (IPv4)	90
DHCP and BOOTP Relay (IPv4)	90
DHCPv6	91
DVMRP	92
IGMP	92
IGMP Proxy	94
IP Helper	94
IP Routing	95
IPv6 Multicast	96
IPv6 Routing	97
Loopback Interface	100
Multicast	101
OSPF	102
OSPFv3	107
PIM-DM	110
PIM-SM	110
Router Discovery Protocol	112
Routing Information Protocol	112
Tunnel Interface	113
Virtual LAN Routing	114
Virtual Router Redundancy	114
Utility Commands	116
Auto Config	116
Captive Portal	116
Clock	118
Configuration and Image Files	119
Denial of Service	120
Line	121
Management ACL	122
Password Management	122
PHY Diagnostics	123
Power Over Ethernet (PoE)	123
RMON	124
Serviceability Tracing	125
sFlow	126
SNMP	127
SSH	128
Syslog	129
System Management	130
Telnet Server	132
User Interface	132
Web Server	133
Using the CLI	135
Introduction	135
Entering and Editing CLI Commands	135
History Buffer	136
Negating Commands	137
Show Command	137
Command Completion	137
Short Form Commands	137
Keyboard Shortcuts	137
Operating on Multiple Objects (Range)	138
Command Scripting	139
CLI Command Notation Conventions	140
Interface Naming Conventions	140
CLI Command Modes	141
User EXEC Mode	142
Privileged EXEC Mode	142
Global Configuration Mode	143
Interface and Other Specific Configuration Modes	143
Identifying the Switch and Command Mode from the System Prompt	145
Navigating CLI Command Modes	146
Starting the CLI	154
Easy Setup Wizard	154
Using CLI Functions and Tools	165
Configuration Management	165
Management Interface Security	167
Management ACAL	170
Other CLI Tools and Capabilities	170
Layer 2 Commands	187
Introduction	187
AAA Commands	188
aaa authentication dot1x	189
Syntax	189
Default Configuration	189
Command Mode	189
User Guidelines	189
Example	189
aaa authentication enable	190
Syntax	190
Default Configuration	190
Command Mode	190
User Guidelines	190
Example	191
aaa authentication login	191
Syntax	191
Default Configuration	192
Command Mode	192
User Guidelines	192
Example	192
aaa authorization network default radius	193
Syntax	193
Default Configuration	193
Command Mode	193
User Guidelines	193
Example	193
enable authentication	194
Syntax	194
Default Configuration	194
Command Mode	194
User Guidelines	194
Example	194
enable password	194
Syntax	195
Default Configuration	195
Command Mode	195
User Guidelines	195
Example	195
ip http authentication	195
Syntax	195
Default Configuration	196
Command Mode	196
User Guidelines	196
Example	196
ip https authentication	196
Syntax	196
Default Configuration	197
Command Mode	197
User Guidelines	197
Example	197
login authentication	197
Syntax	197
Default Configuration	198
Command Mode	198
User Guidelines	198
Example	198
password (Line Configuration)	198
Syntax	198
Default Configuration	199
Command Mode	199
User Guidelines	199
Example	199
password (User EXEC)	199
Syntax	199
Default Configuration	199
Command Mode	199
User Guidelines	199
Example	199
show authentication methods	200
Syntax	200
Default Configuration	200
Command Mode	200
User Guidelines	200
Example	200
show users accounts	201
Syntax	201
Default Configuration	201
Command Mode	201
User Guidelines	201
Example	202
show users login-history	202
Syntax	202
Default Configuration	202
Command Mode	202
User Guidelines	202
Example	202
username	203
Syntax	203
Default Configuration	203
Command Mode	204
User Guidelines	204
Example	204
ACL Commands	205
access-list	206
Syntax	206
Default Configuration	207
Command Mode	207
User Guidelines	207
Examples	207
deny \| permit	207
Syntax	208
Default Configuration	209
Command Mode	209
User Guidelines	209
Example	209
ip access-group	209
no ip access-group	209
Syntax	209
Default Configuration	210
Command Mode	210
User Guidelines	210
Examples	210
mac access-group	210
Syntax	210
Default Configuration	211
Command Mode	211
User Guidelines	211
Example	211
mac access-list extended	211
Syntax	211
Default Configuration	212
Command Mode	212
User Guidelines	212
Example	212
mac access-list extended rename	212
Syntax	212
Default Configuration	212
Command Mode	212
User Guidelines	213
Example	213
show ip access-lists	213
Syntax	213
Examples	213
show mac access-list	214
Syntax	214
Default Configuration	214
Command Mode	214
User Guidelines	214
Example	214
Address Table Commands	217
bridge address	218
Syntax	218
Default Configuration	218
Command Mode	218
User Guidelines	218
Example	218
bridge aging-time	219
Syntax	219
Default Configuration	219
Command Mode	219
User Guidelines	219
Example	219
bridge multicast address	219
Syntax	219
Default Configuration	220
Command Mode	220
User Guidelines	220
Examples	220
bridge multicast filtering	221
Syntax	221
Default Configuration	221
Command Mode	221
User Guidelines	221
Example	221
bridge multicast forbidden address	222
Syntax	222
Default Configuration	222
Command Mode	222
User Guidelines	222
Examples	223
bridge multicast forbidden forward-unregistered	223
Syntax	223
Default Configuration	223
Command Mode	223
User Guidelines	223
Example	223
bridge multicast forward-all	224
Syntax	224
Default Configuration	224
Command Mode	224
User Guidelines	224
Example	224
bridge multicast forward-unregistered	224
Syntax	224
Default Configuration	224
Command Mode	225
User Guidelines	225
Example	225
clear bridge	225
Syntax	225
Default Configuration	225
Command Mode	225
User Guidelines	225
Example	225
port security	226
Syntax	226
Default Configuration	226
Command Mode	226
User Guidelines	226
Example	226
port security max	227
Syntax	227
Default Configuration	227
Command Mode	227
User Guidelines	227
Example	227
show bridge address-table	227
Syntax	227
Default Configuration	228
Command Mode	228
User Guidelines	228
Example	228
show bridge address-table count	228
Syntax	229
Default Configuration	229
Command Mode	229
User Guidelines	229
Example	229
show bridge address-table static	229
Syntax	230
Default Configuration	230
Command Mode	230
User Guidelines	230
Example	230
show bridge multicast address-table	230
Syntax	230
Default Configuration	231
Command Mode	231
User Guidelines	231
Example	231
show bridge multicast filtering	232
Syntax	232
Default Configuration	232
Command Mode	232
User Guidelines	232
Example	232
show ports security	232
Syntax	233
Default Configuration	233
Command Mode	233
User Guidelines	233
Example	233
show ports security addresses	234
Syntax	234
Default Configuration	234
Command Mode	234
User Guidelines	234
Examples	234
CDP Interoperability Commands	237
clear isdp counters	238
Syntax	238
Default Configuration	238
Command Mode	238
User Guidelines	238
Example	238
clear isdp table	238
Syntax	238
Default Configuration	238
Command Mode	238
User Guidelines	238
Example	239
isdp advertise-v2	239
Syntax	239
Default Configuration	239
Command Mode	239
User Guidelines	239
Example	239
isdp enable	239
Syntax	239
Default Configuration	240
Command Mode	240
User Guidelines	240
Example	240
isdp holdtime	240
Syntax	240
Default Configuration	240
Command Mode	240
User Guidelines	241
Example	241
isdp timer	241
Syntax	241
Default Configuration	241
Command Mode	241
User Guidelines	241
Example	241
show isdp	241
Syntax	242
Default Configuration	242
Command Mode	242
User Guidelines	242
Example	242
show isdp entry	243
Syntax	243
Default Configuration	243
Command Mode	243
User Guidelines	243
Example	243
show isdp interface	244
Syntax	244
Default Configuration	244
Command Mode	245
User Guidelines	245
Example	245
show isdp neighbors	246
Syntax	246
Default Configuration	246
Command Mode	246
User Guidelines	247
Example	247
show isdp traffic	248
Syntax	248
Default Configuration	248
Command Mode	248
User Guidelines	248
Example	248
DHCP Layer 2 Relay Commands	251
dhcp l2relay (Global Configuration)	252
Syntax	252
Default Configuration	252
Command Mode	252
User Guidelines	252
Example	252
dhcp l2relay (Interface Configuration)	252
Syntax	252
Default Configuration	252
Command Mode	253
User Guidelines	253
Example	253
dhcp l2relay circuit-id	253
Syntax	253
Default Configuration	253
Command Mode	253
User Guidelines	253
Example	253
dhcp l2relay remote-id	254
Syntax	254
Default Configuration	254
Command Mode	254
User Guidelines	254
Example	254
dhcp l2relay trust	254
Syntax	254
Default Configuration	255
Configuration Mode	255
User Guidelines	255
Example	255
dhcp l2relay vlan	255
Syntax	255
Default Configuration	255
Command Mode	255
User Guidelines	255
Example	256
DHCP Snooping Commands	257
clear ip dhcp snooping statistics	258
Syntax	258
Default Configuration	258
Command Mode	258
User Guidelines	258
Example	258
ip dhcp snooping	258
Syntax	258
Default Configuration	258
Command Mode	258
User Guidelines	259
Example	259
ip dhcp snooping binding	259
Syntax	259
Default Configuration	259
Command Mode	259
User Guidelines	260
Example	260
ip dhcp snooping database	260
Syntax	260
Default Configuration	260
Configuration Mode	260
User Guidelines	260
Example	260
ip dhcp snooping database write-delay	261
Syntax	261
Default Configuration	261
Command Mode	261
User Guidelines	261
Example	261
ip dhcp snooping limit	261
Syntax	262
Default Configuration	262
Command Mode	262
User Guidelines	262
Examples	262
ip dhcp snooping log-invalid	262
Syntax	262
Default Configuration	263
Command Mode	263
User Guidelines	263
Example	263