Home » Dell Manuals » Hubs & Switches » Dell PowerConnect B-RX4 » Manual Viewer

Dell PowerConnect B-RX4 BigIron RX Configuration Guide (Supporting Multi-Servi - Page 853

Using the IP default route as a valid next hop for a BGP4 route, Enabling next-hop recursion

View all Dell PowerConnect B-RX4 manuals

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

Page 853 highlights

Using the IP default route as a valid next hop for a BGP4 route 26 Using the IP default route as a valid next hop for a BGP4 route By default, the device does not use a default route to resolve a BGP4 next-hop route. If the IP route lookup for the BGP4 next hop does not result in a valid IGP route (including static or direct routes), the BGP4 next hop is considered to be unreachable and the BGP4 route is not used. In some cases, such as when the device is acting as an edge router, you might want to allow the device to use the default route as a valid next hop. To do so, enter the following command at the BGP4 configuration level of the CLI. BigIron RX(config-bgp)# next-hop-enable-default Syntax: [no] next-hop-enable-default Enabling next-hop recursion For each BGP4 route a BigIron RX learns, the device performs a route lookup to obtain the IP address of the route's next hop. A BGP4 route becomes eligible for installation into the IP route table only if the following conditions are true: • The lookup succeeds in obtaining a valid next-hop IP address for the route. • The path to the next-hop IP address is an Interior Gateway Protocol (IGP) path or a static route path. By default, the software performs only one lookup for a BGP route's next-hop IP address. If the next-hop lookup does not result in a valid next-hop IP address or the path to the next-hop IP address is a BGP path, the software considers the BGP route's destination to be unreachable. The route is not eligible to be installed in the IP route table. It is possible for the BGP route table to contain a route whose next-hop IP address is not reachable through an IGP route, even though a hop farther away can be reached by the device through an IGP route. This can occur when the IGPs do not learn a complete set of IGP routes, resulting in the device learning about an internal route through IBGP instead of through an IGP. In this case, the IP route table does not contain a route that can be used to reach the BGP route's destination. To enable the device to find the IGP route to a BGP route's next-hop gateway, enable recursive next-hop lookups. When you enable recursive next-hop lookup, if the first lookup for a BGP route results in an IBGP path originated within the same Autonomous System (AS), rather than an IGP path or static route path, the device performs a lookup on the next-hop gateway's next-hop IP address. If this second lookup results in an IGP path, the software considers the BGP route to be valid and thus eligible for installation in the IP route table. Otherwise, the device performs a lookup on the next-hop IP address of the next-hop gateway's next hop, and so on, until one of the lookups results in an IGP route. NOTE You must configure a static route or use an IGP to learn the route to the EBGP multihop peer. BigIron RX Series Configuration Guide 781 53-1001810-01

Section	Page
BigIron RX	1
Contents	3
About This Document	41
In this chapter	41
Audience	41
Supported hardware and software	41
List of supported features	42
Unsupported features	44
What’s new in this document	45
Enhancements and configuration notes in release 02.7.02	45
Enhancements and configuration notes in release 02.7.01	46
Enhancements and configuration notes in release 02.7.00	46
Enhancements and configuration notes in release 02.6.00	48
Enhancements and configuration notes in patch release 02.5.00c	50
Enhancements and configuration notes in patch release 02.5.00b	51
Summary of enhancements and configuration notes in release 02.5.00	51
Summary of enhancements and configuration notes in patch release 02.4.00c	52
Summary of enhancements and configuration notes in release 02.4.00	53
Summary of enhancements in patch release 02.3.00a	57
Summary of enhancements and configuration notes in release 02.3.00	58
Summary of enhancements and configuration notes in 02.2.01	63
Summary of enhancements in release 02.2.00g	67
Summary of enhancements and configuration notes in 02.2.00	68
Document conventions	69
Text formatting	69
Command syntax conventions	69
Notes, cautions, and danger notices	69
Notice to the reader	70
Related publications	70
Getting technical help or reporting errors	70
Web access	71
E-mail access	71
Telephone access	71
Getting Started with the Command Line Interface	73
In this chapter	73
Logging on through the CLI	73
On-line help	74
Command completion	74
Scroll control	74
Line editing commands	75
EXEC commands	75
Global level	76
CONFIG commands	76
Accessing the CLI	79
Navigating among command levels	80
CLI command structure	80
Searching and filtering output	81
Allowable characters for LAG names	86
Syntax shortcuts	86
Saving configuration changes	86
Getting Familiar With the BigIron RX Series Switch Management Applications	89
In this chapter	89
How to manage BigIron RX Series switch	89
Logging on through the CLI	89
On-line help	90
Command completion	90
Scroll control	90
Line editing commands	91
Searching and filtering output from CLI commands	91
Allowable characters for LAG names	95
Logging on through the Web Management Interface	96
Web Management Interface	97
Logging on through IronView Network Manager	98
Using a Redundant Management Module	99
In this chapter	99
How management module redundancy works	99
Management module redundancy overview	99
Management module switchover	100
Switchover implications	101
Management module redundancy configuration	103
Changing the default active Chassis slot	103
Managing management module redundancy	103
File synchronization between the active and standby management modules	104
Manually switching over to the standby management module	106
Rebooting the active and standby management modules	106
Monitoring management module redundancy	107
Determining management module status	107
Displaying temperature information	108
Displaying switchover information	108
Flash memory and PCMCIA flash card file management commands	110
Management focus	111
Flash memory file system	111
PCMCIA flash card file system	112
Wildcards	113
Formatting a flash card	114
Determining the current management focus	114
Switching the management focus	115
Displaying a directory of the files	115
Displaying the contents of a file	117
Displaying the hexadecimal output of a file	118
Creating a subdirectory	118
Removing a subdirectory	120
Renaming a file	121
Changing the read-write attribute of a file	121
Deleting a file	122
Recovering (“undeleting”) a file	123
Appending a file to another file	124
Copying files using the copy command	124
Copying files using the cp command	129
Loading the software	129
Saving configuration changes	131
File management messages	132
Securing Access to Management Functions	133
In this chapter	133
Securing access methods	133
Restricting remote access to management functions	135
Using ACLs to restrict remote access	135
Restricting remote access to the device to specific IP addresses	138
Specifying the maximum number of login attempts for Telnet access	140
Restricting remote access to the device to specific VLAN IDs	140
Disabling specific access methods	141
Setting passwords	143
Setting a Telnet password	143
Setting passwords for management privilege levels	144
Recovering from a lost password	146
Displaying the SNMP community string	146
Disabling password encryption	146
Specifying a minimum password length	147
Setting up local user accounts	147
Configuring a local user account	148
Configuring SSL security for the Web Management Interface	150
Enabling the SSL server on the device	150
Importing digital certificates and RSA private key files	151
Generating an SSL certificate	151
Configuring TACACS/TACACS+ security	152
How TACACS+ differs from TACACS	152
TACACS/TACACS+ authentication, authorization, and accounting	152
TACACS/TACACS+ configuration considerations	156
Enabling SNMP to configure TACACS/TACACS	157
Identifying the TACACS/TACACS+ servers	157
Specifying different servers for individual AAA functions	158
Setting optional TACACS/TACACS+ parameters	158
Configuring authentication-method lists for TACACS/TACACS+	160
Configuring TACACS+ authorization	161
Configuring TACACS+ accounting	164
Configuring an interface as the source for all TACACS/TACACS+ packets	166
Displaying TACACS/TACACS+ statistics and configuration information	167
Configuring RADIUS security	168
RADIUS authentication, authorization, and accounting	168
RADIUS configuration considerations	171
RADIUS configuration procedure	171
Configuring Brocade-specific attributes on the RADIUS server	172
Enabling SNMP to configure RADIUS	173
Identifying the RADIUS server to the BigIron RX	173
Specifying different servers for individual AAA functions	174
Setting RADIUS parameters	174
Configuring authentication-method lists for RADIUS	175
Configuring RADIUS authorization	176
Configuring RADIUS accounting	178
Configuring an interface as the source for all RADIUS packets	179
Displaying RADIUS configuration information	180
Configuring authentication-method lists	181
Configuration considerations for authentication-method lists	182
Examples of authentication-method lists	183
Configuring Basic Parameters	185
In this chapter	185
Entering system administration information	186
Configuring Simple Network Management Protocol(SNMP) traps	186
Specifying an SNMP trap receiver	187
Specifying a Single trap source	187
Setting the SNMP Trap holddown time	188
Disabling SNMP traps	188
Disabling Syslog messages and traps for CLI access	189
Configuring an interface as the source for all Telnet packets	190
Cancelling an outbound Telnet session	191
Configuring an interface as the source for all TFTP packets	191
Configuring an interface as the source for Syslog packets	192
Specifying a Simple Network Time Protocol (SNTP) server	193
Setting the system clock	194
New Daylight Saving Time (DST)	196
Configuring CLI banners	196
Setting a message of the day banner	196
Setting a privileged EXEC CLI level banner	197
Displaying a message on the console when an incoming Telnet session is detected	197
Configuring terminal display	198
Checking the length of terminal displays	198
Enabling or disabling routing protocols	198
Displaying and modifying system parameter default settings	199
Enabling or disabling Layer 2 switching	201
CAM partitioning for the BigIron RX	202
Re-distributing CAM allocations	202
Nexthop table	203
Changing the MAC age time	204
Configuring static ARP entries	204
Configuring Interface Parameters	205
In this chapter	205
Assigning a port name	205
Assigning an IP address to a port	206
Speed/Duplex negotiation	206
Disabling or re-enabling a port	207
Changing the default Gigabit negotiation mode	208
Changing the negotiation mode	208
Disabling or re-enabling flow control	208
Specifying threshold values for flow control	209
Locking a port to restrict addresses	209
Wait for all cards feature	210
Port transition hold timer	210
Port flap dampening	210
Modifying port priority (QoS)	212
Assigning a mirror port and monitor ports	212
Configuration guidelines for monitoring traffic	213
Configuring port mirroring and monitoring	213
Monitoring an individual trunk port	214
Mirror ports for Policy-Based Routing (PBR) traffic	215
About hardware-based PBR	215
Configuring mirror ports for PBR traffic	215
Displaying mirror and monitor port configuration	216
Enabling WAN PHY mode support	216
Configuring IP	217
In this chapter	217
Overview of configuring IP	217
The IP packet flow	218
ARP cache table	219
Static ARP table	219
IP Route table	220
IP forwarding cache	221
Basic IP parameters and defaults	221
When parameter changes take effect	221
IP global parameters	222
IP interface parameters	224
Configuring IP parameters	225
Configuring IP addresses	226
Changing the network mask display to prefix format	228
Configuring the default gateway	229
GRE IP tunnel	229
IPv6 over IPv4 tunnels in hardware	234
Configuring Domain Name Server (DNS) resolver	238
Adding host names to the DNS cache table	239
Configuring packet parameters	243
Changing the encapsulation type	243
Setting maximum frame size per PPCR	244
Changing the MTU	245
Changing the router ID	246
Specifying a single source interface for Telnet, TACACS/TACACS+, or RADIUS packets	247
Configuring an interface as the source for Syslog packets	249
IP fragmentation protection	250
IP option attack protection	250
IP receive access list	250
Configuring ARP parameters	251
How ARP works	251
Rate limiting ARP packets	252
Applying a rate limit to ARP packets on an interface	253
Clearing the rate limit for ARP packets	254
Changing the ARP aging period	254
Creating a floating static ARP entry	256
Static route ARP validation check	257
Configuring forwarding parameters	258
Disabling ICMP messages	260
Disabling ICMP redirect messages	262
Configuring static routes	263
Static route tagging	268
Configuring a default network route	272
Configuring IP load sharing	273
Default route ECMP	276
IP receive access list	277
Configuring IRDP	278
Configuring UDP broadcast and IP helper parameters	280
Configuring BootP/DHCP forwarding parameters	283
Displaying IP information	285
Displaying IP interface information	287
Displaying interface name in Syslog	288
Displaying ARP entries	289
Displaying the forwarding cache	291
Displaying the IP route table	292
Clearing IP routes	295
Displaying IP traffic statistics	295
Displaying TCP traffic statistics	298
Link Aggregation	301
In this chapter	301
Link aggregation overview	301
LAG formation rules	302
LAG load sharing	304
Hash based load sharing	304
Migration from a pre-02.6.00 trunk or LACP configuration	305
Configuration of a LAG	306
Creating a Link Aggregation Group (LAG)	307
Deploying a LAG	309
Commands available under LAG once it is deployed	310
Configuring ACL-based mirroring	310
Disabling ports within a LAG	311
Enabling ports within a LAG	311
Monitoring an individual LAG port	311
Assigning a name to a port within a LAG	312
Enabling sFlow forwarding on a port within a LAG	312
Setting the sFlow sampling rate for a port within a LAG	312
Displaying LAG information	313
Displaying LAG statistics	317
Configuring LLDP	319
In this chapter	319
Terms used in this chapter	319
LLDP overview	320
Benefits of LLDP	320
General operating principles	321
Operating modes	321
LLDP packets	322
TLV support	322
MIB support	325
Syslog messages	325
Configuring LLDP	325
Configuration notes and considerations	326
Enabling and disabling LLDP	326
Changing a port’s LLDP operating mode	327
Specifying the maximum number of LLDP neighbors	328
Enabling LLDP SNMP notifications and Syslog messages	329
Specifying the minimum time between SNMP traps and Syslog messages	329
Changing the minimum time between LLDP transmissions	330
Changing the interval between regular LLDP transmissions	330
Changing the holdtime multiplier for transmit TTL	331
Changing the minimum time between port reinitializations	331
LLDP TLVs advertised by the Brocade device	332
Displaying LLDP statistics and configuration settings	338
LLDP configuration summary	338
LLDP statistics	339
LLDP neighbors	340
LLDP neighbors detail	341
LLDP configuration details	343
Resetting LLDP statistics	344
Configuring Uni-Directional Link Detection (UDLD)	345
In this chapter	345
Configuration considerations	346
Configuring UDLD	346
Changing the keepalive interval	346
Changing the keepalive retries	347
Displaying UDLD information	347
Displaying information for all ports	347
Displaying link-keepalive information	347
Displaying information for a single port	349
Clearing UDLD statistics	350
VLANs	351
In this chapter	351
Overview of Virtual Local Area Networks (VLANs)	351
Tagged, untagged, and dual-mode ports	351
Protocol-based VLANs	353
VLAN configuration rules	354
VLAN ID range	354
Tagged VLANs	354
VLAN hierarchy	354
Multiple VLAN membership rules	355
Layer 2 control protocols on VLANs	355
Configuring port-based VLANs	355
VLAN byte accounting	356
Strictly or explicitly tagging a port	358
Assigning or changing a VLAN priority	358
Assigning a different ID to the default VLAN	359
Configuring protocol-based VLANs	359
Configuring an MSTP instance	360
Configuring virtual routing interfaces	360
Bridging and routing the same protocol simultaneously on the same device	361
Integrated Switch Routing (ISR)	362
VLAN groups	363
Configuring a VLAN group	363
Configuring super aggregated VLANs	365
Configuring aggregated VLANs	367
Complete CLI examples	368
Configuring 802.1q-in-q tagging	371
Configuration rules	372
Enabling 802.1Q-in-Q tagging	372
Example configuration	374
Configuring 802.1q tag-type translation	374
Configuration rules	376
Enabling 802.1q tag-type translation	377
Private VLANs	378
Implementation notes	379
Configuration notes	379
Configuring a private VLAN	380
Enabling broadcast, multicast or unknown unicast traffic to the private VLAN	382
CLI example for Figure 30	383
Other VLAN features	383
Allocating memory for more VLANs or virtual routing interfaces	383
Hardware flooding for Layer 2 multicast and broadcast packets	383
Unknown unicast flooding on VLAN ports	384
Flow based MAC learning	385
Configuring uplink ports within a port-based VLAN	385
Configuring control protocols in VLANs	386
Other configuration options	386
Displaying VLAN information	386
Displaying VLAN information	386
Displaying VLAN information for specific ports	387
Displaying VLAN status and port types	388
Displaying VLAN group information	389
Transparent firewall mode	389
Enabling a transparent firewall	389
Configuring Spanning Tree Protocol	391
In this chapter	391
IEEE 802.1D Spanning Tree Protocol (STP)	391
Enabling or disabling STP	391
Default STP bridge and port parameters	393
Changing STP bridge parameters	394
Changing STP port parameters	394
STP root guard	394
Spanning Tree Protocol (STP) BPDU guard	396
Displaying STP information	396
IEEE Single Spanning Tree (SSTP)	402
SSTP defaults	402
Enabling SSTP	403
Displaying SSTP information	404
PVST/PVST+ compatibility	404
Overview of PVST and PVST+	405
VLAN tags and dual mode	405
Enabling PVST+ support	406
Displaying PVST+ support information	406
Configuration examples	407
SuperSpan™	409
Customer ID	410
BPDU forwarding	410
Configuring SuperSpan	415
Configuring Rapid Spanning Tree Protocol	419
In this chapter	419
Overview of Rapid Spanning Tree Protocol	419
Bridges and bridge port roles	419
Assignment of port roles	420
Ports on Switch 1	421
Ports on Switch 2	421
Ports on Switch 3	421
Ports Switch 4	422
Edge ports and edge port roles	422
Point-to-point ports	423
Bridge port states	423
Edge port and non-edge port states	424
Changes to port roles and states	424
State machines	424
Handshake mechanisms	425
Convergence in a simple topology	435
Convergence at start up	436
Convergence after a link failure	438
Convergence at link restoration	439
Convergence in a complex RSTP topology	441
Propagation of topology change	443
Compatibility of RSTP with 802.1D	446
Configuring RSTP parameters	447
Enabling or disabling RSTP in a port-based VLAN	447
Enabling or disabling RSTP on a single spanning tree	448
Disabling or enabling RSTP on a port	448
Changing RSTP bridge parameters	448
Changing port parameters	449
Fast port span	450
Fast uplink span	453
Displaying RSTP information	455
Metro Ring Protocol (MRP) Phase 1 and 2	459
In this chapter	459
Metro Ring Protocol (MRP) phase 1	459
MRP rings without shared interfaces	461
Ring initialization	462
How ring breaks are detected and healed	465
Master VLANs and customer VLANs in a topology group	466
Configuring MRP	467
Adding an MRP ring to a VLAN	468
Changing the hello and preforwarding times	469
MRP phase 2	469
Ring initialization for shared interfaces	471
How ring breaks Are detected and healed between shared interfaces	472
Selection of master node	472
RHP processing in rings with shared interfaces	473
Normal flow	473
Flow when a link breaks	474
Configuring MRP with shared interfaces	475
Using MRP diagnostics	476
Enabling MRP diagnostics	476
Displaying MRP diagnostics	476
Displaying MRP information	477
Displaying topology group information	477
Displaying ring information	478
MRP CLI example	479
Commands on switch A (master node)	480
Commands on switch B	480
Commands on switch C	481
Commands on switch D	481
Virtual Switch Redundancy Protocol (VSRP)	483
In this chapter	483
Overview of Virtual Switch Redundancy Protocol (VSRP)	483
Layer 2 and Layer 3 redundancy	485
Master election and failover	485
Configuring basic VSRP parameters	490
Enabling Layer 3 VSRP	491
Configuring optional VSRP parameters	491
Disabling VSRP on a VRID	491
Configuring authentication	491
Configuring a VRID IP address	492
VSRP fast start	493
Changing the backup priority	494
Saving the timer values received from the master	494
VSRP slow start	495
Changing the Time-To-Live (TTL)	495
Changing the hello interval	496
Changing the dead interval	496
Changing the backup hello state and interval	496
Changing the hold-down interval	497
Changing the default track priority	497
Specifying a track port	498
Disabling or re-enabling backup pre-emption	498
Port transition hold timer	498
Clearing VSRP information	499
VSRP and MRP signaling	499
Displaying VSRP information	501
Displaying VRID information	501
Displaying a summary of VSRP information	503
Displaying VSRP packet statistics for VSRP	504
Displaying the active interfaces for a VRID	505
Topology Groups	507
In this chapter	507

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
1,312
1,313
1,314
1,315
1,316
1,317
1,318
1,319
1,320
1,321
1,322
1,323
1,324
1,325
1,326
1,327
1,328
1,329
1,330
1,331
1,332
1,333
1,334
1,335
1,336
1,337
1,338
1,339
1,340
1,341
1,342
1,343
1,344
1,345
1,346
1,347
1,348
1,349
1,350
1,351
1,352
1,353
1,354
1,355
1,356
1,357
1,358
1,359
1,360
1,361
1,362
1,363
1,364
1,365
1,366
1,367
1,368
1,369
1,370
1,371
1,372
1,373
1,374
1,375
1,376
1,377
1,378
1,379
1,380
1,381
1,382
1,383
1,384
1,385
1,386
1,387
1,388
1,389
1,390
1,391
1,392
1,393
1,394
1,395
1,396
1,397
1,398
1,399
1,400
1,401
1,402
1,403
1,404
1,405
1,406
1,407
1,408
1,409
1,410
1,411
1,412
1,413
1,414
1,415
1,416
1,417
1,418
1,419
1,420
1,421
1,422
1,423
1,424
1,425
1,426
1,427
1,428
1,429
1,430
1,431
1,432
1,433
1,434
1,435
1,436

Match case Limit results 1 per page

BigIron RX Series Configuration Guide

781

53-1001810-01

Using the IP default route as a valid next hop for a BGP4 route

By default, the device does not use a default route to resolve a BGP4 next-hop route. If the IP route

lookup for the BGP4 next hop does not result in a valid IGP route (including static or direct routes),

the BGP4 next hop is considered to be unreachable and the BGP4 route is not used.

In some cases, such as when the device is acting as an edge router, you might want to allow the

device to use the default route as a valid next hop. To do so, enter the following command at the

BGP4 configuration level of the CLI.

BigIron RX(config-bgp)# next-hop-enable-default

Syntax:

[no] next-hop-enable-default

Enabling next-hop recursion

For each BGP4 route a BigIron RX learns, the device performs a route lookup to obtain the IP

address of the route’s next hop. A BGP4 route becomes eligible for installation into the IP route

table only if the following conditions are true:

•

The lookup succeeds in obtaining a valid next-hop IP address for the route.

•

The path to the next-hop IP address is an Interior Gateway Protocol (IGP) path or a static route

path.

By default, the software performs only one lookup for a BGP route’s next-hop IP address.

If the

next-hop lookup does not result in a valid next-hop IP address or the path to the next-hop IP

address is a BGP path, the software considers the BGP route’s destination to be unreachable.

The

route is not eligible to be installed in the IP route table.

It is possible for the BGP route table to contain a route whose next-hop IP address is not reachable

through an IGP route, even though a hop farther away can be reached by the device through an IGP

route. This can occur when the IGPs do not learn a complete set of IGP routes, resulting in the

device learning about an internal route through IBGP instead of through an IGP. In this case, the IP

route table does not contain a route that can be used to reach the BGP route’s destination.

To enable the device to find the IGP route to a BGP route’s next-hop gateway, enable recursive

next-hop lookups. When you enable recursive next-hop lookup, if the first lookup for a BGP route

results in an IBGP path originated within the same Autonomous System (AS), rather than an IGP

path or static route path, the device performs a lookup on the next-hop gateway’s next-hop IP

address. If this second lookup results in an IGP path, the software considers the BGP route to be

valid and thus eligible for installation in the IP route table. Otherwise, the device performs a lookup

on the next-hop IP address of the next-hop gateway’s next hop, and so on, until one of the lookups

results in an IGP route.

NOTE

You must configure a static route or use an IGP to learn the route to the EBGP multihop peer.