BFD協(xié)議原理及應(yīng)用

1、0網(wǎng)絡(luò)發(fā)展需求和現(xiàn)狀網(wǎng)絡(luò)發(fā)展需求和現(xiàn)狀l快速檢測相鄰系統(tǒng)之間的通信故障，并快速檢測相鄰系統(tǒng)之間的通信故障，并切換到備份路徑是可靠網(wǎng)絡(luò)的必備功能；切換到備份路徑是可靠網(wǎng)絡(luò)的必備功能；l采用采用“慢慢Hello”機(jī)制的控制協(xié)議檢測時機(jī)制的控制協(xié)議檢測時間以秒為單位，無法實現(xiàn)快速檢測；間以秒為單位，無法實現(xiàn)快速檢測；l控制協(xié)議一般只能完成控制層面的檢測，控制協(xié)議一般只能完成控制層面的檢測，無法做到對轉(zhuǎn)發(fā)層面的快速檢測；無法做到對轉(zhuǎn)發(fā)層面的快速檢測；l一些硬件檢測可以快速發(fā)現(xiàn)轉(zhuǎn)發(fā)故障一些硬件檢測可以快速發(fā)現(xiàn)轉(zhuǎn)發(fā)故障（如（如SDH），但并不是所有介質(zhì)都支持），但并不是所有介質(zhì)都支持這樣的硬件檢測。這樣的

2、硬件檢測。1BFD的誕生的誕生l一種通用的檢測鄰居間轉(zhuǎn)發(fā)路徑可用性一種通用的檢測鄰居間轉(zhuǎn)發(fā)路徑可用性的協(xié)議呼之欲出的協(xié)議呼之欲出lBFD（Bidirectional Forwarding Detection）雙向轉(zhuǎn)發(fā)檢測誕生）雙向轉(zhuǎn)發(fā)檢測誕生IETF標(biāo)準(zhǔn) RFC5880專注于故障快速檢測，且輕負(fù)荷專注于轉(zhuǎn)發(fā)平面檢測與傳輸介質(zhì)和底層協(xié)議無關(guān)為上層控制協(xié)議提供檢測服務(wù)，自身不作為無發(fā)現(xiàn)機(jī)制，由上層協(xié)議提供鄰居信息n BFD的誕生的誕生n BFD協(xié)議原理協(xié)議原理n BFD協(xié)議典型協(xié)議典型應(yīng)用應(yīng)用n BFD配置問題探討配置問題探討目錄目錄3BFD會話的觸發(fā)會話的觸發(fā)lBFD會話的觸發(fā)過程會話的觸發(fā)過程

3、上層協(xié)議如OSPF發(fā)現(xiàn)鄰居OSPF通知BFD與鄰居建立會話BFD向鄰居建立會話OSPF PeersBFD PeersOSPF informsBFD the 4BFD鄰居的角色鄰居的角色lBFD鄰居角色鄰居角色Active: 可以主動發(fā)起會話建立Passive：不可以主動發(fā)起會話，被動接受；How are you?FineHow are you?Fine!ActiveActiveActiveP5BFD會話的建立和拆除會話的建立和拆除三次握手三次握手lBFD會話建立和拆除都是三次握手會話建立和拆除都是三次握手DownDown - InitBFD DownInit - UpABBFD InitBFD

4、 UpInit - UpDownUp- DownBFD DownUp- DownBFD DownBFD DownDownD6BFD的操作模式的操作模式lBFD有兩種操作模式有兩種操作模式異步模式（ Asynchronous ）查詢模式（Demand）UpUpIm alive!Im alive too!UpU7BFD的輔助功能的輔助功能EcholBFD的回聲功能同樣可以實現(xiàn)雙向檢測的回聲功能同樣可以實現(xiàn)雙向檢測需要鄰居雙方都支持在任何一個方向可選使能僅在UP狀態(tài)發(fā)送EchoHi!8BFD會話會話Down通知通知lBDF會話會話Down后通知上層協(xié)議采取動作后通知上層協(xié)議采取動作OSPF neig

5、hbor relationship is overBFD detects failure, session state becomes DOWNBFD informsOSPF, the peeris 9BFD重要參數(shù)重要參數(shù)l定時器定時器min-transmit-interval， BFD 控制報文的最小發(fā)送時間min-echo-receive-interval，系統(tǒng)接收 BFD echo 報文的最小時間間隔min-receive-interval， BFD 控制報文的最小接收時間間隔detect-multiplier， BFD 報文最大失效的個數(shù)lEcho源地址源地址echo-source-

6、ip， BFD echo 報文源IP 地址n BFD的誕生的誕生n BFD協(xié)議原理協(xié)議原理n BFD應(yīng)用舉例應(yīng)用舉例n BFD配置問題探討配置問題探討目錄目錄11BFD典型應(yīng)用概述典型應(yīng)用概述lBFD與靜態(tài)路由聯(lián)動與靜態(tài)路由聯(lián)動lBFD與動態(tài)路由協(xié)議聯(lián)動與動態(tài)路由協(xié)議聯(lián)動lBFD與與MPLS聯(lián)動聯(lián)動lBFD與與Track聯(lián)動聯(lián)動12BFD與與Track聯(lián)動聯(lián)動lBDF與與Track聯(lián)動實現(xiàn)聯(lián)動實現(xiàn)VRRP快速倒換快速倒換SmartBitsS95E-1Vlan100: 100.1.1.1Vlan 10: 10.1.1.14/0/234/0/234/0/164/0/16VRRP: 100.1.1.

7、254Vlan100: 100.1.1.2S95E-2Vlan 10: 10.1.1.2Port1/1: 100.1.1.3Port1/2: 10.1.1.3Port1/3: 10.1.1.31/0/11/0/13測試步驟和預(yù)期結(jié)果測試步驟和預(yù)期結(jié)果l測試步驟測試步驟從SMB的Port 1向10.1.1.3的地址發(fā)包，經(jīng)過VRRP組轉(zhuǎn)發(fā)后，由SMB的Port 2或Port 3收到；在沒有啟用BFD檢測的情況下，測試VRRP的Master故障造成的中斷時間；在啟用了BFD檢測，并與Track和VRRP聯(lián)動的情況下，測試VRRP的Master故障造成的中斷時間；l預(yù)期結(jié)果預(yù)期結(jié)果沒有啟用BFD時，

8、中斷時間為秒級啟用BFD后，中斷時間為毫秒級14BFD相關(guān)配置相關(guān)配置l配置配置BFDbfd echo-source-ip 1.1.1.1interface Vlan-interface100bfd min-echo-receive-interval 10bfd detect-multiplier 3l配置配置Track聯(lián)動聯(lián)動track 10 bfd echo interface Vlan-interface100 remote ip 100.1.1.1 local ip 100.1.1.2l配置配置VRRP聯(lián)動聯(lián)動vrrp vrid 1 track 10 15測試數(shù)據(jù)測試數(shù)據(jù)Test1Te

9、st2Test3Test4Test5Test6Port 1267155316132033019819235476123829522110861Port 2836384470042627105931000632461900139Port 315151958188042054057141983517469521207032發(fā)包速率(p/ms)100100100100100100中斷時間(ms)16測試結(jié)論測試結(jié)論l測試結(jié)論：測試結(jié)論：沒有啟用BFD時，VRRP的Master故障，VRRP備份組通過協(xié)議自己的Hello機(jī)制檢測故障。中斷時間約為3秒。啟用BFD時，通過 Track與VRRP聯(lián)動， V

10、RRP的Master故障后，BFD首先發(fā)現(xiàn)線路中斷，隨即通知Track。Track啟動Switchover的動作，將原Slave切換成新的Master。中斷時間約為30多毫秒；通過使用BFD協(xié)議，VRRP備份組對轉(zhuǎn)發(fā)路徑故障的感應(yīng)靈敏度大大的提高了，故障造成的中斷時間也由秒級達(dá)到毫秒級，實現(xiàn)了VRRP的快速倒換。17n BFD的誕生的誕生n BFD協(xié)議原理協(xié)議原理n BFD應(yīng)用舉例應(yīng)用舉例n BFD配置問題探討配置問題探討目錄目錄18SMBG5/0/1G5/0/1VLAN100G5/0/2Port1Port2G5/0/2S125_1S125_2測試一、拓?fù)浼霸O(shè)備配置l 關(guān)鍵配置：關(guān)鍵配置：兩個

11、千兆電口聚合,在三層接口上啟用OSPF BFD功能；啟用ospf功能，把兩端的Loopback地址3.3.3.3和4.4.4.4引入到ospf中；OSPF PeerBFD PeerL1：3.3.3.3L1：19測試一、鏈路聚合/BFD/OSPF 狀態(tài)125-1-Vlan-interface100display link-aggregation verbose Local: Port Status Priority Oper-Key Flag - GE5/0/1 S 32768 1 ACDEF GE5/0/2 S 32768 1 ACDEFRemote: Actor Partner Priori

12、ty Oper-Key SystemID Flag - GE5/0/1 9 32768 1 0 x8000, 0023-893d-1c00 ACDEF GE5/0/2 10 32768 1 0 x8000, 0023-893d-1c00 ACDEF125-1-Vlan-interface100display bfd session LD/RD SourceAddr DestAddr State Holdtime Interface 4/4 1.1.1.1 1.1.1.2 Up 600ms Vlan100125-1-Vlan-interface100dis ip router-tableRout

13、ing Tables: Public Destinations : 6 Routes : 6Destination/Mask Proto Pre Cost NextHop Interface4.4.4.4/32 O_ASE 150 1 1.1.1.2 V20SMBG5/0/1G5/0/1VLAN100G5/0/2Port1Port2G5/0/2S125_1S125_2測試一、Shutdown其中一個端口l shutdown其中一個端口：其中一個端口：125-2-GigabitEthernet5/0/1shutdownX21測試一、測試結(jié)果125-1-Vlan-interface100ping

14、-c 1000 4.4.4.4 PING 4.4.4.4: 56 data bytes, press CTRL_C to break Reply from 4.4.4.4: bytes=56 Sequence=34 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=35 ttl=255 time=1 ms%Sep 2 19:38:11:269 2010 125-1 BFD/4/LOG:Sess1.1.1.1/1.1.1.2,Vlan100,Ctrl, Sta: UP-DOWN, Diag: 5%Sep 2 19:38:11:381

15、2010 125-1 RM/3/RMLOG:OSPF-NBRCHANGE: Process 1, Neighbor 1.1.1.2(Vlan-interface100) from Full to Down Request time out%Sep 2 19:38:12:969 2010 125-1 IFNET/4/LINK UPDOWN: GigabitEthernet5/0/1: link status is DOWN Reply from 4.4.4.4: bytes=56 Sequence=37 ttl=255 time=1 ms%Sep 2 19:38:13:080 2010 125-

16、1 LAGG/2/LAGG_LOG: Port member GigabitEthernet5/0/1 of aggregation group BAGG1 becomes INACTIVE, because the ports configuration is improper for aggregation. Reply from 4.4.4.4: bytes=56 Sequence=38 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=39 ttl=255 time=1 ms Reply from 4.4.4.4: byte

17、s=56 Sequence=40 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=41 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=42 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=43 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=44 ttl=255 time=1 ms Request time out Request time

18、 out Request time out%Sep 2 19:38:15:175 2010 125-1 RM/3/RMLOG:OSPF-NBRCHANGE: Process 1, Neighbor 1.1.1.2(Vlan-interface100) from Loading to Full Reply from 4.4.4.4: bytes=56 Sequence=45 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=46 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequen

19、ce=47 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=48 ttl=255 time=1 ms%Sep 2 19:38:16:200 2010 125-1 BFD/4/LOG:Sess1.1.1.1/1.1.1.2,Vlan100,Ctrl, Sta: DOWN-UP, Diag: 0Reply from 4.4.4.4: bytes=56 Sequence=52 ttl=255 time=1 22測試一、進(jìn)一步測試（1）l 更改配置更改配置：更改BFD檢測時間為900ms；測試結(jié)果正常。125-1-Vlan-interfa

20、ce100ping -c 1000 4.4.4.4 PING 4.4.4.4: 56 data bytes, press CTRL_C to break Reply from 4.4.4.4: bytes=56 Sequence=34 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=35 ttl=255 time=1 ms Request time out%Sep 2 19:38:12:969 2010 125-1 IFNET/4/LINK UPDOWN: GigabitEthernet5/0/1: link status is

21、DOWN Reply from 4.4.4.4: bytes=56 Sequence=37 ttl=255 time=1 ms%Sep 2 19:38:13:080 2010 125-1 LAGG/2/LAGG_LOG: Port member GigabitEthernet5/0/1 of aggregation group BAGG1 becomes INACTIVE, because the ports configuration is improper for aggregation. Reply from 4.4.4.4: bytes=56 Sequence=38 ttl=255 t

22、ime=1 ms Reply from 4.4.4.4: bytes=56 Sequence=39 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=40 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=41 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=42 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=43 ttl=255 time=1

23、 ms Reply from 4.4.4.4: bytes=56 Sequence=44 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=45 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=46 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=47 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=48 ttl=255 time=1 23測試

24、一、進(jìn)一步測試（2）l 更改配置更改配置：刪除BFD功能；測試結(jié)果正常。125-1-Vlan-interface100ping -c 1000 4.4.4.4 PING 4.4.4.4: 56 data bytes, press CTRL_C to break Reply from 4.4.4.4: bytes=56 Sequence=26 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=27 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=28 ttl=255 ti

25、me=1 ms Reply from 4.4.4.4: bytes=56 Sequence=29 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=30 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=31 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=32 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=33 ttl=255 time=1

26、ms Reply from 4.4.4.4: bytes=56 Sequence=34 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=35 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=36 ttl=255 time=1 ms%Sep 3 15:18:51:889 2010 125-1 IFNET/4/LINK UPDOWN: Ten-GigabitEthernet3/0/2: link status is DOWN %Sep 3 15:18:52:000 201

27、0 125-1 LAGG/2/LAGG_LOG: Port member Ten-GigabitEthernet3/0/2 of aggregation group BAGG1 becomes INACTIVE, because the ports configuration is improper for aggregation. Request time out Reply from 4.4.4.4: bytes=56 Sequence=38 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=39 ttl=255 time=1

28、ms Reply from 4.4.4.4: bytes=56 Sequence=40 ttl=255 time=1 ms 24SMBT3/0/2T3/0/2VLAN100T3/0/4Port1Port2T3/0/4S125_1S125_2測試二、拓?fù)浼霸O(shè)備配置l 關(guān)鍵配置：關(guān)鍵配置：兩個萬兆光接口聚合,在三層接口上啟用OSPF BFD功能；啟用ospf功能，把兩端的Loopback地址3.3.3.3和4.4.4.4引入到ospf中；OSPF PeerBFD PeerL1：3.3.3.3L1：25測試二、鏈路聚合/BFD/OSPF 狀態(tài)125-1display link-aggregation

29、 verbose System ID: 0 x8000, 0023-893c-f800Local: Port Status Priority Oper-Key Flag - XGE3/0/2 S 32768 1 ACDEF XGE3/0/4 S 32768 1 ACDEFRemote: Actor Partner Priority Oper-Key SystemID Flag - XGE3/0/2 107 32768 1 0 x8000, 0023-893d-1c00 ACDEF XGE3/0/4 108 32768 1 0 x8000, 0023-893d-1c00 ACDEF125-1di

30、sp125-1display bfd sessionLD/RD SourceAddr DestAddr State Holdtime Interface 11/11 1.1.1.1 1.1.1.2 Up 20ms Vlan100125-1disp ip rouDestination/Mask Proto Pre Cost NextHop Interface4.4.4.4/32 O_ASE 150 1 1.1.1.2 V26測試二、測試結(jié)果125-1-Vlan-interface100ping -c 10000 4.4.4.4 PING 4.4.4.4: 56 data bytes, press

31、 CTRL_C to breakReply from 4.4.4.4: bytes=56 Sequence=330 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=331 ttl=255 time=1 ms%Sep 3 09:05:54:662 2010 125-1 IFNET/4/LINK UPDOWN: Ten-GigabitEthernet3/0/2: link status is DOWN %Sep 3 09:05:54:774 2010 125-1 LAGG/2/LAGG_LOG: Port member Ten-Gig

32、abitEthernet3/0/2 of aggregation group BAGG1 becomes INACTIVE, because the ports configuration is improper for aggregation. Request time out Reply from 4.4.4.4: bytes=56 Sequence=333 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=334 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=335 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=336 ttl=255 time=1 ms Reply from 4.4.4.4: bytes=56 Sequence=337 tt