Home » D-Link Manuals » Wireless » D-Link DGS-1520 » Manual Viewer

D-Link DGS-1520 Emulator - Page 588

Loopback Detection LBD Commands

Add to My Manuals
Save this manual to your list of manuals

Page 588 highlights

55. DGS-1520 Series Gigabit Ethernet Smart Managed Switch CLI Reference Guide Loopback Detection (LBD) Commands 55-1 loopback-detection (Global) This command is used to enable the loopback detection function globally. Use the no form of this command to disable the function globally. loopback-detection [mode {port-based | vlan-based}] no loopback-detection [mode] Parameters mode port-based vlan-based (Optional) Specifies the detection mode. (Optional) Specifies that loop detection will work in the port-based mode. (Optional) Specifies that loop detection will work in the VLAN-based mode. Default By default, this option is disabled. By default, the detection mode is port-based. Command Mode Global Configuration Mode. Command Default Level Level: 12. Usage Guideline Generally, port-based loop detection is used on ports that are connected to users, and VLAN-based detection is used in trunk or hybrid ports when the partner switch does not support the loop detection function. When port-based detection is enabled, the LBD enabled port will send untagged port-based LBD packets out from the port to discover the loop. If there is a loop occurrence in the path, the packet being transmitted will loop back to the same port or to another port located on the same device. When an LBD enabled port detects a loop condition, packet transmitting and receiving is disabled on the port. When VLAN-based detection is enabled, the port will periodically send VLAN-based LBD packets for each VLAN that the port has membership in and is enabled for loop detection. If the port is a tagged member of the detecting VLAN, tagged LBD packets are sent. If the port is an untagged member of the detecting VLAN, untagged LBD packets are sent. If there is a loop occurrence on the VLAN path, packet transmitting and receiving will be temporarily stopped in the looping VLAN at the port where the loop is detected. If an LBD disabled port receives an LBD packet and detects that the packet is sent out by the system itself, the sending port will be blocked if the packet is a port-based LBD packet, or the VLAN of the sending port will be blocked if the packet is a VLAN-based LBD packet. If the port is configured for VLAN-based detection and the port is an untagged member of multiple VLANs, the port will send one untagged LBD packet for each VLAN with the VLAN number specified in the VLAN field of the packet. There are two ways to recover an error disabled port. The user can use the errdisable recovery cause loopbackdetect command to enable the auto-recovery of ports that were disabled by loopback detection. Alternatively, manually recover the port by entering the shutdown command followed by the no shutdown command for the port. The VLAN being blocked on a port can be automatically recovered, if the errdisable recovery cause loopbackdetect command is configured. Alternatively, manually recover the operation by entering the shutdown command followed by the no shutdown command for the port. 584

Section	Page
Table of Contents	2
1. Introduction	5
Audience	5
Other Documentation	5
Conventions	5
Notes, Notices, and Cautions	5
Connecting to the Console Port	6
Command Descriptions	6
Command Modes	6
User EXEC Mode at Basic User Level	8
Privileged EXEC Mode at Operator Level	8
Privileged EXEC Mode at Administrator Level	8
Global Configuration Mode	8
Interface Configuration Mode	8
Creating a User Account	8
Interface Notation	9
Error Messages	10
Editing Features	11
Display Result Output Modifiers	11
2. Basic CLI Commands	13
2-1 help	13
Parameters	13
Default	13
Command Mode	13
Command Default Level	13
Usage Guideline	13
Example	13
2-2 enable	14
Parameters	14
Default	14
Command Mode	15
Command Default Level	15
Usage Guideline	15
Example	15
2-3 disable	15
Parameters	15
Default	15
Command Mode	15
Command Default Level	15
Usage Guideline	15
Example	16
2-4 configure terminal	16
Parameters	16
Default	16
Command Mode	16
Command Default Level	16
Usage Guideline	16
Example	16
2-5 login (EXEC)	16
Parameters	16
Default	17
Command Mode	17
Command Default Level	17
Usage Guideline	17
Example	17
2-6 login (Line)	17
Parameters	17
Default	17
Command Mode	17
Command Default Level	17
Usage Guideline	17
Example	18
2-7 logout	19
Parameters	19
Default	19
Command Mode	19
Command Default Level	19
Usage Guideline	19
Example	19
2-8 end	19
Parameters	19
Default	19
Command Mode	19
Command Default Level	20
Usage Guideline	20
Example	20
2-9 exit	20
Parameters	20
Default	20
Command Mode	20
Command Default Level	20
Usage Guideline	20
Example	20
2-10 show history	21
Parameters	21
Default	21
Command Mode	21
Command Default Level	21
Usage Guideline	21
Example	21
2-11 password-recovery	21
Parameters	21
Default	22
Command Mode	22
Command Default Level	22
Usage Guideline	22
Example	22
2-12 show environment	22
Parameters	22
Default	23
Command Mode	23
Command Default Level	23
Usage Guideline	23
Example	23
Display Parameters	23
2-13 show unit	24
Parameters	24
Default	24
Command Mode	24
Command Default Level	24
Usage Guideline	24
Example	24
2-14 show cpu utilization	24
Parameters	24
Default	25
Command Mode	25
Command Default Level	25
Usage Guideline	25
Example	25
2-15 show version	25
Parameters	26
Default	26
Command Mode	26
Command Default Level	26
Usage Guideline	26
Example	26
2-16 snmp-server enable traps environment	26
Parameters	26
Default	27
Command Mode	27
Command Default Level	27
Usage Guideline	27
Example	27
2-17 environment temperature threshold	27
Parameters	27
Default	27
Command Mode	27
Command Default Level	27
Usage Guideline	28
Example	28
2-18 show memory utilization	28
Parameters	28
Default	28
Command Mode	28
Command Default Level	28
Usage Guideline	28
Example	29
2-19 privilege	29
Parameters	29
Default	29
Command Mode	29
Command Default Level	29
Usage Guideline	29
Example	30
2-20 show privilege	30
Parameters	30
Default	30
Command Mode	30
Command Default Level	30
Usage Guideline	30
Example	30
3. 802.1X Commands	31
3-1 clear dot1x counters	31
Parameters	31
Default	31
Command Mode	31
Command Default Level	31
Usage Guideline	31
Example	31
3-2 dot1x control-direction	31
Parameters	31
Default	32
Command Mode	32
Command Default Level	32
Usage Guideline	32
Example	32
3-3 dot1x default	32
Parameters	32
Default	32
Command Mode	33
Command Default Level	33
Usage Guideline	33
Example	33
3-4 dot1x port-control	33
Parameters	33
Default	33
Command Mode	33
Command Default Level	33
Usage Guideline	33
Example	34
3-5 dot1x forward-pdu	34
Parameters	34
Default	34
Command Mode	34
Command Default Level	34
Usage Guideline	34
Example	34
3-6 dot1x initialize	34
Parameters	35
Default	35
Command Mode	35
Command Default Level	35
Usage Guideline	35
Example	35
3-7 dot1x max-req	35
Parameters	35
Default	35
Command Mode	36
Command Default Level	36
Usage Guideline	36
Example	36
3-8 dot1x pae authenticator	36
Parameters	36
Default	36
Command Mode	36
Command Default Level	36
Usage Guideline	36
Example	37
3-9 dot1x re-authenticate	37
Parameters	37
Default	37
Command Mode	37
Command Default Level	37
Usage Guideline	37
Example	38
3-10 dot1x system-auth-control	38
Parameters	38
Default	38
Command Mode	38
Command Default Level	38
Usage Guideline	38
Example	38
3-11 dot1x timeout	38
Parameters	39
Default	39
Command Mode	39
Command Default Level	39
Usage Guideline	39
Example	39
3-12 show dot1x	39
Parameters	39
Default	40
Command Mode	40
Command Default Level	40
Usage Guideline	40
Example	40
3-13 show dot1x diagnostics	40
Parameters	41
Default	41
Command Mode	41
Command Default Level	41
Usage Guideline	41
Example	41
3-14 show dot1x statistics	42
Parameters	42
Default	42
Command Mode	42
Command Default Level	42
Usage Guideline	42
Example	42
3-15 show dot1x session-statistics	43
Parameters	43
Default	43
Command Mode	43
Command Default Level	43
Usage Guideline	43
Example	43
3-16 snmp-server enable traps dot1x	43
Parameters	44
Default	44
Command Mode	44
Command Default Level	44
Usage Guideline	44
Example	44
4. Access Control List (ACL) Commands	45
4-1 access-list resequence	45
Parameters	45
Default	45
Command Mode	45
Command Default Level	45
Usage Guideline	45
Example	46
4-2 acl-hardware-counter	46
Parameters	46
Default	47
Command Mode	47
Command Default Level	47
Usage Guideline	47
Example	47
4-3 action	47
Parameters	47
Default	47
Command Mode	47
Command Default Level	47
Usage Guideline	48
Example	48
4-4 clear acl-hardware-counter	48
Parameters	48
Default	48
Command Mode	48
Command Default Level	48
Usage Guideline	49
Example	49
4-5 expert access-group	49
Parameters	49
Default	49
Command Mode	49
Command Default Level	49
Usage Guideline	49
Example	50
4-6 expert access-list	50
Parameters	50
Default	50
Command Mode	50
Command Default Level	50
Usage Guideline	50
Example	50
4-7 ip access-group	51
Parameters	51
Default	51
Command Mode	51
Command Default Level	51
Usage Guideline	51
Example	51
4-8 ip access-list	51
Parameters	52
Default	52
Command Mode	52
Command Default Level	52
Usage Guideline	52
Example	52
4-9 ipv6 access-group	52
Parameters	53
Default	53
Command Mode	53
Command Default Level	53
Usage Guideline	53
Example	53
4-10 ipv6 access-list	53
Parameters	53
Default	54
Command Mode	54
Command Default Level	54
Usage Guideline	54
Example	54
4-11 list-remark	54
Parameters	54
Default	54
Command Mode	55
Command Default Level	55
Usage Guideline	55
Example	55
4-12 mac access-group	55
Parameters	55
Default	55
Command Mode	55
Command Default Level	56
Usage Guideline	56
Example	56
4-13 mac access-list	56
Parameters	56
Default	56
Command Mode	56
Command Default Level	56
Usage Guideline	56
Example	57
4-14 match ip address	57
Parameters	57
Default	57
Command Mode	57
Command Default Level	57
Usage Guideline	57
Example	58
4-15 match ipv6 address	58
Parameters	58
Default	58
Command Mode	58
Command Default Level	58
Usage Guideline	58
Example	59
4-16 match mac address	59
Parameters	59
Default	59
Command Mode	59
Command Default Level	59
Usage Guideline	59
Example	60
4-17 permit \| deny \| deny-cpu (expert access-list)	60
Parameters	61
Default	62
Command Mode	62
Command Default Level	62
Usage Guideline	62
Example	63
4-18 permit \| deny \| deny-cpu (ip access-list)	63
Parameters	64
Default	65
Command Mode	65
Command Default Level	65
Usage Guideline	65
Example	66
4-19 permit \| deny \| deny-cpu (ipv6 access-list)	66
Parameters	67
Default	68
Command Mode	68
Command Default Level	68
Usage Guideline	68
Example	68
4-20 permit \| deny \| deny-cpu (mac access-list)	69
Parameters	69
Default	70
Command Mode	70
Command Default Level	70
Usage Guideline	70
Example	70
4-21 show access-group	70
Parameters	70
Default	71
Command Mode	71
Command Default Level	71
Usage Guideline	71
Example	71
4-22 show access-list	71
Parameters	71
Default	71
Command Mode	71
Command Default Level	72
Usage Guideline	72
Example	72
4-23 show vlan access-map	72
Parameters	73
Default	73
Command Mode	73
Command Default Level	73
Usage Guideline	73
Example	73
4-24 show vlan filter	74
Parameters	74
Default	74
Command Mode	74
Command Default Level	74
Usage Guideline	74
Example	74
4-25 vlan access-map	74
Parameters	75
Default	75
Command Mode	75
Command Default Level	75
Usage Guideline	75
Example	75
4-26 vlan filter	75
Parameters	75
Default	76
Command Mode	76
Command Default Level	76
Usage Guideline	76
Example	76
5. Access Management Commands	77
5-1 access class	77
Parameters	77
Default	77
Command Mode	77
Command Default Level	77
Usage Guideline	77
Example	77
5-2 banner login	77
Parameters	78
Default	78
Command Mode	78
Command Default Level	78
Usage Guideline	78
Example	78
5-3 do	78
Parameters	79
Default	79
Command Mode	79
Command Default Level	79
Usage Guideline	79
Example	79
5-4 prompt	79
Parameters	79
Default	80
Command Mode	80
Command Default Level	80
Usage Guideline	80
Example	80
5-5 enable password	80
Parameters	80
Default	81
Command Mode	81
Command Default Level	81
Usage Guideline	81
Example	81
5-6 ip http server	81
Parameters	81
Default	81
Command Mode	81
Command Default Level	81
Usage Guideline	81
Example	82

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1,000
1,001
1,002
1,003
1,004
1,005
1,006
1,007
1,008
1,009
1,010
1,011
1,012
1,013
1,014
1,015
1,016
1,017
1,018
1,019
1,020
1,021
1,022
1,023
1,024
1,025
1,026
1,027
1,028
1,029
1,030
1,031
1,032
1,033
1,034
1,035
1,036
1,037
1,038
1,039
1,040
1,041
1,042
1,043
1,044
1,045
1,046
1,047
1,048
1,049
1,050
1,051
1,052
1,053
1,054
1,055
1,056
1,057
1,058
1,059
1,060
1,061
1,062
1,063
1,064
1,065
1,066
1,067
1,068
1,069
1,070
1,071
1,072
1,073
1,074
1,075
1,076
1,077
1,078
1,079
1,080
1,081
1,082
1,083
1,084
1,085
1,086
1,087
1,088
1,089
1,090
1,091
1,092
1,093
1,094
1,095
1,096
1,097
1,098
1,099
1,100
1,101
1,102
1,103
1,104
1,105
1,106
1,107
1,108
1,109
1,110
1,111
1,112
1,113
1,114
1,115
1,116
1,117
1,118
1,119
1,120
1,121
1,122
1,123
1,124
1,125
1,126
1,127
1,128
1,129
1,130
1,131
1,132
1,133
1,134
1,135
1,136
1,137
1,138
1,139
1,140
1,141
1,142
1,143
1,144
1,145
1,146
1,147
1,148
1,149
1,150
1,151
1,152
1,153
1,154
1,155
1,156
1,157
1,158
1,159
1,160
1,161
1,162
1,163
1,164
1,165
1,166
1,167
1,168
1,169
1,170
1,171
1,172
1,173
1,174
1,175
1,176
1,177
1,178
1,179
1,180
1,181
1,182
1,183
1,184
1,185
1,186
1,187
1,188
1,189
1,190
1,191
1,192
1,193
1,194
1,195
1,196
1,197
1,198
1,199
1,200
1,201
1,202
1,203
1,204
1,205
1,206
1,207
1,208
1,209
1,210
1,211
1,212
1,213
1,214
1,215
1,216
1,217
1,218
1,219
1,220
1,221
1,222
1,223
1,224
1,225
1,226
1,227
1,228
1,229
1,230
1,231
1,232
1,233
1,234
1,235
1,236
1,237
1,238
1,239
1,240
1,241
1,242
1,243
1,244
1,245
1,246
1,247
1,248
1,249
1,250
1,251
1,252
1,253
1,254
1,255
1,256
1,257
1,258
1,259
1,260
1,261
1,262
1,263
1,264
1,265
1,266
1,267
1,268
1,269
1,270
1,271
1,272
1,273
1,274
1,275
1,276
1,277
1,278
1,279
1,280
1,281
1,282
1,283
1,284
1,285
1,286
1,287
1,288
1,289
1,290
1,291
1,292
1,293
1,294
1,295
1,296
1,297
1,298
1,299
1,300
1,301
1,302
1,303
1,304
1,305
1,306
1,307
1,308
1,309
1,310
1,311

Match case Limit results 1 per page

DGS-1520 Series Gigabit Ethernet Smart Managed Switch CLI Reference Guide

584

55.

Loopback Detection (LBD) Commands

55-1

loopback-detection (Global)

This command is used to enable the loopback detection function globally. Use the

form of this command to

disable the function globally.

loopback-detection [mode {port-based | vlan-based}]

no loopback-detection [mode]

Parameters

mode

(Optional) Specifies the detection mode.

port-based

(Optional) Specifies that loop detection will work in the port-based mode.

vlan-based

(Optional) Specifies that loop detection will work in the VLAN-based mode.

Default

By default, this option is disabled.

By default, the detection mode is port-based.

Command Mode

Global Configuration Mode.

Command Default Level

Level: 12.

Usage Guideline

Generally, port-based loop detection is used on ports that are connected to users, and VLAN-based detection is

used in trunk or hybrid ports when the partner switch does not support the loop detection function.

When port-based detection is enabled, the LBD enabled port will send untagged port-based LBD packets out from

the port to discover the loop. If there is a loop occurrence in the path, the packet being transmitted will loop back to

the same port or to another port located on the same device. When an LBD enabled port detects a loop condition,

packet transmitting and receiving is disabled on the port.

When VLAN-based detection is enabled, the port will periodically send VLAN-based LBD packets for each VLAN

that the port has membership in and is enabled for loop detection. If the port is a tagged member of the detecting

VLAN, tagged LBD packets are sent. If the port is an untagged member of the detecting VLAN, untagged LBD

packets are sent. If there is a loop occurrence on the VLAN path, packet transmitting and receiving will be

temporarily stopped in the looping VLAN at the port where the loop is detected.

If an LBD disabled port receives an LBD packet and detects that the packet is sent out by the system itself, the

sending port will be blocked if the packet is a port-based LBD packet, or the VLAN of the sending port will be

blocked if the packet is a VLAN-based LBD packet.

If the port is configured for VLAN-based detection and the port is an untagged member of multiple VLANs, the port

will send one untagged LBD packet for each VLAN with the VLAN number specified in the VLAN field of the

packet.

There are two ways to recover an error disabled port. The user can use the

errdisable recovery cause loopback-

detect

command to enable the auto-recovery of ports that were disabled by loopback detection. Alternatively,

manually recover the port by entering the

shutdown

command followed by the

no shutdown

command for the

port.

The VLAN being blocked on a port can be automatically recovered, if the

errdisable recovery cause loopback-

detect

command is configured. Alternatively, manually recover the operation by entering the

shutdown

command

followed by the

no shutdown

command for the port.