BackboneFast是对UplinkFast的一¿U补充,UplinkFast能够‹‚€‹¹‹ç›´˜qžé“¾è·¯çš„失效åQ?/span>BackboneFastæ˜¯ç”¨æ¥æ£€‹¹‹é—´æŽ¥é“¾è·¯çš„失效。当å¯ç”¨äº?/span>BackboneFastçš„äº¤æ¢æœº‹‚€‹¹‹åˆ°é—´æŽ¥é“¾èµ\失效之åŽåQŒä¼šé©¬ä¸Šä½‰K˜»å¡žçš„端壘q›å…¥ç›‘å¬çжæ€ï¼Œž®‘了20Sçš„è€åŒ–æ—‰™—´ã€‚左边的囑֒Œä¸‹é¢çš„图凿¥è‡ªæ€ç§‘的官æ–ÒŽ–‡æ¡£ï¼š
  在æ£å¸¸æƒ…况下åQ?/span>Switch C上å³è¾¹çš„端å£ä¼šå¤„äº?/span>Blocking状æ€ï¼Œå½?/span>L1的链路å‘生故障的时候,虽然è¯?/span>Switch C是检‹¹‹ä¸åˆŽÍ¼Œä½†æ˜¯Switch Bä¼šè®¤ä¸ø™‡ªå·Þqš„è·Ÿæ¡¥åQŒç„¶åŽé€šè¿‡L3链èµ\å‘é€?/span>BPDUã€?/span>Switch C收到˜q™ä¸ªBPDU之åŽåQŒå‘现是‹Æ¡çñ”BPDUåQŒæ‰€ä»¥ç¡®å®šæœ‰éžç›´˜qžé“¾è·¯çš„æ•…éšœã€?/span>Switch Cä¼šä»Žæ ¹ç«¯å£å‘é€?/span>RLQåQ?/span>Switch AåQˆæ ¹æ¡¥ï¼‰æŽ¥åˆ°RLQåQŒä»¥RLQå“应˜q›è¡Œåº”ç”åQ?/span>Switch C收到SwitchAçš?/span>RLQå“应åQŒçŸ¥é“æ ¹æ¡¥è¿˜åœ¨ï¼Œç„¶åŽæŠŠå³è¾¹çš„端å£ä»?/span>blocking直接˜q‡åŽ»åˆ?/span>Listening状æ€ï¼Œå¦‚下图所½Cºã€?/span>
  å½?/span>L1链èµ\æ¢å¤çš„æ—¶å€™ï¼ŒBackboneFast会马上把Switch C上å³ä¾§çš„端å£çš„状æ€è®¾ä¸?/span>blockingã€?/span>
  从ä¸åŒçš„ç«¯å£æ”¶åˆ°‹Æ¡çñ”BPDU的情况:
  1. å½“äº¤æ¢æœºä»Žé˜»å¡žç«¯å£æ”¶åˆ°æ¬¡¾U?/span>BPDUçš„æ—¶å€™ï¼Œé‚£ä¹ˆè¯¥äº¤æ¢æœºä¸Šçš„æ ¹ç«¯å£å’Œå…¶ä»–é˜Õd¡žç«¯å£ž®†æˆä¸ºåˆ°è¾¾æ ¹æ¡¥çš„æ›¿ä»£è·¯å¾„ã€?/span>
  2. å½“äº¤æ¢æœºä»Žæ ¹ç«¯å£æ”¶åˆ°‹Æ¡çñ”BPDUåQŒé‚£ä¹ˆå½“剿‰€æœ‰çš„é˜Õd¡žç«¯å£éƒ½å°†æˆäؓ辑ֈ°æ ÒŽ¡¥çš„æ›¿ä»£èµ\径ã€?/span>
  3. å½“äº¤æ¢æœºä»Žæ ¹ç«¯å£æ”¶åˆ°‹Æ¡çñ”BPDUåQŒåÆˆä¸”äº¤æ¢æœºä¸Šä¸å˜åœ¨é˜Õd¡žç«¯å£çš„è¯åQŒé‚£ä¹ˆäº¤æ¢æœºè®¤å®šåˆ°è¾¾æ ÒŽ¡¥çš„链路已¾l?/span>down掉了åQŒåœ¨è€åŒ–æ—‰™—´åˆîCº†ä¹‹åŽåQŒäº¤æ¢æœºž®†é€šè¿‡æŠŠè‡ªå·±å®£å‘ŠäØ“æ ÒŽ¡¥å¼€å§‹æ£å¸¸çš„STP选ä‹D˜q‡ç¨‹ã€?/span>
  é…ç½®BackboneFast
  Switch(config)#spanning-tree backbonefast
  注æ„事项
  如果è¦å¯ç”?/span>BackboneFastç‰ÒŽ€§ï¼Œæˆ‘们应该在网¾lœä¸çš„æ‰€æœ‰äº¤æ¢æœºä¸Šéƒ½å¯ç”¨ã€?/span>
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Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#host R1
R1(config)#no ip domain-lo
R1(config)#int s 0/0
R1(config-if)#ip add 172.18.0.1 255.255.0.0
R1(config-if)#cl ra 64000
R1(config-if)#no shut
R1(config-if)#int s 0/1
R1(config-if)#ip add 172.16.0.1 255.255.0.0
R1(config-if)#cl ra 64000
R1(config-if)#no shut
R1(config-if)#exit
R1(config)#enable secret cisco
R1(config)#lin con 0
R1(config-line)#password cisco
R1(config-line)#login
R1(config-line)#logg sy
R1(config-line)#exec-t 0 0
R1(config-line)#exit
R1(config)#lin vty 0 4
R1(config-line)#pas
R1(config-line)#password cisco
R1(config-line)#login
R1(config-line)#exit
R1(config)#service password-encryption
R2é…ç½®åQ?/span>
Router>
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#no ip domain-lo
Router(config)#lin con 0
Router(config-line)#exec-t 0 0
Router(config-line)#logg sy
Router(config-line)#pas cisco
Router(config-line)#lin vty 0 4
Router(config-line)#pas cisco
Router(config-line)#login
Router(config-line)#exit
Router(config)#enable se cisco
Router(config)#ser pas
Router(config)#int s 0/0
Router(config-if)#ip add 172.18.0.2 255.255.0.0
Router(config-if)#no shut
%LINK-5-CHANGED: Interface Serial0/0, changed state to up
Router(config-if)#
Router(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
i
Router(config-if)#int s 0/1
Router(config-if)#ip add 172.17.0.1 255.255.0.0
Router(config-if)#cl ra 64000
Router(config-if)#no shut
%LINK-5-CHANGED: Interface Serial0/1, changed state to down
Router(config-if)#int f 0/0
Router(config-if)#ip add 10.13.0.1 255.0.0.0
Router(config-if)#no shut
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
Router(config-if)#
Router(config-if)#host R2
R2(config)#
R3é…ç½®
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#no ip domain-lo
Router(config)#host R3
R3(config)#enable se cisco
R3(config)#lin con 0
R3(config-line)#pas cisco
R3(config-line)#login
R3(config-line)#exec-t 0 0
R3(config-line)#logg sy
R3(config-line)#lin vty 0 4
R3(config-line)#pas cisco
R3(config-line)#login
R3(config-line)#exit
R3(config)#ser pas
R3(config)#int s 0/0
R3(config-if)#ip add 172.17.0.2 255.255.0.0
R3(config-if)#no shut
%LINK-5-CHANGED: Interface Serial0/0, changed state to up
R3(config-if)#
R3(config-if)#int s 0/1
R3(config-if)#ip add 172.16.
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
R3(config-if)#ip add 172.16.0.2 255.255.0.0
R3(config-if)#no shut
R3(config-if)#
%LINK-5-CHANGED: Interface Serial0/1, changed state to up
R3(config-if)#int f 0/0
R3(config-if)#ip add 1
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/1, changed state to up
R3(config-if)#ip add 192.168.1.1 255.255.255.0
R3(config-if)#no shut
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
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