试验、BGP的基本配置步骤：1、基本的直连配置r1(config)#int lo0r1(config-if)#ip add 1.1.1.1 255.255.255.0r1(config-if)#int s0/0r1(config-if)#ip add 199.99.1.1 255.255.255.0r1(config-if)#no shutr2(config)#int s0/0r2(config-if)#ip add 199.99.1.2 255.255.255.0r2(config-if)#no shutr2(config)#int s0/1r2(config-if)#ip add 199.99.2.1 255.255.255.0r2(config-if)#no shutr3(config)#int s0/0r3(config-if)#ip add 199.99.2.2 255.255.255.0r3(config-if)#no shut2、BGP的配置r1(config)#router bgp 100r1(config-router)#neighbor 199.99.1.2 remote-as 200定义我的bgp邻居，as号是200r2(config)#router bgp 200r2(config-router)#nei 199.99.1.1 remote-as 100r2(config-router)#nei 199.99.2.2 remote-as 200定义我的邻居，AS号是200，跟我的进程一致，说明是IBGPr3(config)#router bgp 200r3(config-router)#nei 199.99.2.1 remote-as 200r1(config)#int lo1r1(config-if)#ip add 10.10.10.10 255.255.255.0r1(config-if)#int lo2r1(config-if)#ip add 110.110.110.110 255.255.255.0第一个宣告我采用的是network标准宣告！！！！r1(config)#router bgp 100r1(config-router)#net 1.1.1.0 mask 255.255.255.0这条路由会进入到bgp的路由表，并且随着bgp的路由传递给下一个ebgp或者ibgp的邻居r1#sh ip bgp 查看bgp的路由表BGP table version is 2, local router ID is 1.1.1.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 1.1.1.0/24 0.0.0.0 0 32768 i*=可用的>=最优的Network=宣告的前缀Next Hop=0.0.0.0 自己产生Metric=度量值，直连进来的，当然为0LocPrf =本地优先属性，只在IBGP之间传递Weight=权重属性Path=AS-path路径属性I=起源属性，I代表的是来自IGP的路由我们再来到R1的EBGP对等体邻居来看一下bgp的路由表r2#sh ip bgpBGP table version is 2, local router ID is 199.99.2.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path *> 1.1.1.0/24 199.99.1.1 0 0 100 i我们再来R2的IBGP对等体R3来看一下有什么区别？r3#sh ip bgpBGP table version is 1, local router ID is 199.99.2.2Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path * i1.1.1.0/24 199.99.1.1 0 100 0 100 i 没有>，没有最优的路由，？？？？？？？？？？？？？？？？？？I=代表的是从IBGP传递过来的，而不是起源属性解决的方法：修改R2到R3的下一跳为自己！！！！！（****）r2(config)#router bgp 200r2(config-router)#nei 199.99.2.2 next-hop-selfr3#sh ip bgpBGP table version is 4, local router ID is 199.99.2.2Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path *>i1.1.1.0/24 199.99.2.1 0 100 0 100 i *>i10.0.0.0 199.99.2.1 0 100 0 100 i *>i110.110.110.0/24 199.99.2.1 0 100 0 100 ?修改后，就正确了！！！r3#sh ip routeCodes: C - connected, S - static, R - RIP, M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2ia - IS-IS inter area, * - candidate default, U - per-user static routeo - ODR, P - periodic downloaded static routeGateway of last resort is not set1.0.0.0/24 is subnetted, 1 subnetsB 1.1.1.0 [200/0] via 199.99.2.1, 00:00:49110.0.0.0/24 is subnetted, 1 subnetsB 110.110.110.0 [200/0] via 199.99.2.1, 00:00:49C 199.99.2.0/24 is directly connected, Serial0/0B 10.0.0.0/8 [200/0] via 199.99.2.1, 00:00:49下面我们来进行第二个宣告，故意宣告错误，查看结果！！！！！r1(config)#router bgp 100r1(config-router)#net 10.0.0.0 mask 255.0.0.0r1(config)#ip route 10.0.0.0 255.0.0.0 null 0r1#sh ip bgpBGP table version is 3, local router ID is 1.1.1.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 1.1.1.0/24 0.0.0.0 0 32768 i*> 10.0.0.0 0.0.0.0 0 32768 i下面我们来进行第三种宣告，利用在发布宣告lo2接口r1(config)#route-map fxh permit 10r1(config-route-map)#match inter lo2抓去接口lo2r1(config-route-map)#exitr1(config)#router bgp 100r1(config-router)#red connr1(config-router)#red connected route-map fxh在发布直连链路，利用route-map做控制，并且进入到bgp的路由r1# sh ip bgpBGP table version is 4, local router ID is 1.1.1.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,r RIB-failure, S StaleOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 1.1.1.0/24 0.0.0.0 0 32768 i*> 10.0.0.0 0.0.0.0 0 32768 i*> 110.110.110.0/24 0.0.0.0 0 32768 ??=代表在发布IGP路由进入到BGP中！！！！！3、测试和排错r2#sh ip bgp neighbors 查看BGP的邻居BGP neighbor is 199.99.1.1, remote AS 100, external link（这个是EBGP的邻居）BGP version 4, remote router ID 1.1.1.1（跟ospf的路由ID的意思是一致的）BGP state = Established（一定是这个状态，才代表BGP完全的起来）, up for 00:00:50Last read 00:00:20, hold time is 180, keepalive interval is 60 seconds（来检查邻居持续性）Neighbor capabilities:Route refresh: advertised and received(old & new)Address family IPv4 Unicast: advertised and received（MPLS-VPN了）Message statistics:InQ depth is 0OutQ depth is 0Sent RcvdOpens: 1 1Notifications: 0 0Updates: 0 0Keepalives: 2 2Route Refresh: 0 0Total: 3 3Default minimum time between advertisement runs is 30 secondsFor address family: IPv4 UnicastBGP table version 1, neighbor version 0/0Output queue sizes : 0 self, 0 replicatedIndex 1, Offset 0, Mask 0x21 update-group memberSent RcvdPrefix activity: ---- ----Prefixes Current: 0 0Prefixes Total: 0 0Implicit Withdraw: 0 0Explicit Withdraw: 0 0Used as bestpath: n/a 0Used as multipath: n/a 0Outbound InboundLocal Policy Denied Prefixes: -------- -------Total: 0 0Number of NLRIs in the update sent: max 0, min 0Connections established 1; dropped 0Last reset neverConnection state is ESTAB, I/O status: 1, unread input bytes: 0Connection is ECN DisabledLocal host: 199.99.1.2, Local port: 11001Foreign host: 199.99.1.1, Foreign port: 179Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)Event Timers (current time is 0x5FCFC):Timer Starts Wakeups NextRetrans 4 0 0x0TimeWait 0 0 0x0AckHold 2 0 0x0SendWnd 0 0 0x0KeepAlive 0 0 0x0GiveUp 0 0 0x0PmtuAger 0 0 0x0DeadWait 0 0 0x0iss: 376417542 snduna: 376417626 sndnxt: 376417626 sndwnd: 16301 irs: 1565270957 rcvnxt: 1565271041 rcvwnd: 16301 delrcvwnd: 83SRTT: 124 ms, RTTO: 1405 ms, RTV: 1281 ms, KRTT: 0 msminRTT: 80 ms, maxRTT: 300 ms, ACK hold: 200 msFlags: active open, nagleIP Precedence value : 6Datagrams (max data segment is 1460 bytes):Rcvd: 5 (out of order: 0), with data: 2, total data bytes: 83Sent: 5 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data:3, total data bytes: 83BGP neighbor is 199.99.2.2, remote AS 200, internal link（说明是IBGP）BGP version 4, remote router ID 199.99.2.2BGP state = Established, up for 00:00:16Last read 00:00:16, hold time is 180, keepalive interval is 60 secondsNeighbor capabilities:Route refresh: advertised and received(old & new)Address family IPv4 Unicast: advertised and receivedMessage statistics:InQ depth is 0OutQ depth is 0Sent RcvdOpens: 1 1Notifications: 0 0Updates: 0 0Keepalives: 1 1Route Refresh: 0 0Total: 2 2Default minimum time between advertisement runs is 5 secondsFor address family: IPv4 UnicastBGP table version 1, neighbor version 0/0Output queue sizes : 0 self, 0 replicatedIndex 2, Offset 0, Mask 0x42 update-group memberSent RcvdPrefix activity: ---- ----Prefixes Current: 0 0Prefixes Total: 0 0Implicit Withdraw: 0 0Explicit Withdraw: 0 0Used as bestpath: n/a 0Used as multipath: n/a 0Outbound Inbound Local Policy Denied Prefixes: -------- -------Total: 0 0Number of NLRIs in the update sent: max 0, min 0Connections established 1; dropped 0Last reset neverConnection state is ESTAB, I/O status: 1, unread input bytes: 0Connection is ECN DisabledLocal host: 199.99.2.1, Local port: 179Foreign host: 199.99.2.2, Foreign port: 11000Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)Event Timers (current time is 0x5FF34):Timer Starts Wakeups NextRetrans 2 0 0x0TimeWait 0 0 0x0AckHold 2 1 0x0SendWnd 0 0 0x0KeepAlive 0 0 0x0GiveUp 0 0 0x0PmtuAger 0 0 0x0DeadWait 0 0 0x0iss: 576524820 snduna: 576524885 sndnxt: 576524885 sndwnd: 16320 irs: 1116395438 rcvnxt: 1116395503 rcvwnd: 16320 delrcvwnd: 64SRTT: 70 ms, RTTO: 1683 ms, RTV: 1613 ms, KRTT: 0 msminRTT: 52 ms, maxRTT: 300 ms, ACK hold: 200 msFlags: passive open, nagle, gen tcbsIP Precedence value : 6Datagrams (max data segment is 1460 bytes):Rcvd: 4 (out of order: 0), with data: 2, total data bytes: 64Sent: 3 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 1, total data bytes: 64实验：BGP的一些特性还是继续上面的实验！！！！！删除R2和R3的bgp，重新配置r2(config)#no router bgp 200r3(config)#no router bgp 200r2(config)#int lo0r2(config-if)#ip add 2.2.2.2 255.255.255.0r3(config)#int lo0r3(config-if)#ip add 3.3.3.3 255.255.255.0确保两个lo的可达性！！！r2(config)#ip route 3.3.3.0 255.255.255.0 199.99.2.2r3(config)#ip route 2.2.2.0 255.255.255.0 199.99.2.1r2(config)#router bgp 200r2(config-router)#nei 199.99.1.1 remote-as 100r2(config-router)#nei 3.3.3.3 remote-as 200定义我的IBGP邻居r2(config-router)#nei 3.3.3.3 upr2(config-router)#nei 3.3.3.3 update-source lo0定义我的IBGP的邻居的更新源为lo0（重点，这个lo0指的是你自己的lo接口，而不是对方）r3(config)#router bgp 200r3(config-router)#nei 2.2.2.2 remote-as 200r3(config-router)#nei 2.2.2.2 upr3(config-router)#nei 2.2.2.2 update-source lo0r2(config)#router bgp 200r2(config-router)#nei 3.3.3.3 nexr2(config-router)#nei 3.3.3.3 next-hop-S定义邻居3.3.3.3到自己的下一跳是自己。
