BGP公网常见问题

BGP公网常见问题Page2BGP邻居异常的定位思路Page3BGP邻居无法建立常见问题BGP邻居未使能/未配置没有配置connect-interface本地被shutdown邻居未协商路由问题MD5认证/TTL错误EBGP邻居没有ebgp-max-hop

Page4BGP有限状态机-ConnectPage5Q1：BGP邻居无法建立的可能原因bgp12479router-id10.34.0.12groupLEVEL1_IPV4externalpeerLEVEL1_IPV4ignore //邻居被shutdownpeerLEVEL1_IPV4connect-interfaceLoopBack0 //没有配置connect-interfacepeerLEVEL1_IPV4valid-ttl-hops2 //valid-ttl-hop设置错误或未使能eBGP-max-hoppeerLEVEL1_IPV4passwordcipher>8*$OV‘“C1P$UV=;M\D’4A!! //MD5密码不一致peer193.149.1.192as-number12478peer193.149.1.192groupLEVEL1_IPV4#ipv4-familyunicastundosynchronizationpeerLEVEL1_IPV4enableundopeer193.149.1.192enable //BGP邻居未使能peer193.149.1.192groupLEVEL1_IPV4Page6Q2:本地被shutdown[RT1-bgp]displaybgppeerBGPlocalrouterID:10.34.0.12LocalASnumber:12479Totalnumberofpeers:1Peersinestablishedstate:0Peer VAS MsgRcvdMsgSentOutQ Up/DownState PrefRcv193.149.1.192 412478000 00:03:17 Idle(Admin)0[RT1-bgp]邻居被shutdownPage7Q3:邻居未协商[RT1-bgp]displaybgppeer //本地未在IPv4单播上使能[RT1-bgp][RT1-bgp]displaybgpvpnv4allpeerBGPlocalrouterID:10.34.0.12LocalASnumber:12479Totalnumberofpeers:1Peersinestablishedstate:0PeerVASMsgRcvdMsgSentOutQUp/DownState PrefRcv193.149.1.19241247800000:03:17 Established

0[RT1-bgp]displaybgpl2vpnpeerBGPlocalrouterID:10.34.0.12LocalASnumber:12479Totalnumberofpeers:1Peersinestablishedstate:0PeerVASMsgRcvdMsgSentOutQUp/DownState PrefRcv193.149.1.19241247800000:03:17 Noneg 0本地配置了该地址族，但邻居未使能Page8Q4:路由问题[RT1]displayiprouting-table193.149.1.192 //没有IGP路由[RT1][RT1]displaycurrent-configurationinterfaceLoopBack0#interfaceLoopBack0ipaddress193.149.1.191255.255.255.255#return[RT1]ping-a193.149.1.191193.149.1.192 //带源地址ping不通邻居PING193.149.1.192:56databytes,pressCTRL_CtobreakRequesttimeoutRequesttimeoutPage9Q5:MD5认证/TTL错误<RT1>distcpstatusremote-ip193.149.1.192TCPCBTid/SoidLocalAdd:portForeignAdd:portVPNIDState6ebdab10135/2140.0.0.0:179193.149.1.192:00Listening

*<RT1>distcpstatusremote-ip193.149.1.192TCPCBTid/SoidLocalAdd:portForeignAdd:portVPNIDState6ebdab10135/2140.0.0.0:179193.149.1.192:00Listening*55419288135/17193.149.1.140:50731193.149.1.192:1790Syn_Sent*MD5认证TCP三次握手无法建立Page10判断BGP邻居中断原因[RT1]displaybgppeer202.112.146.100log-infoPeer:202.112.146.100Date Time StateErrorNotification

2011/09/2114:09:51UTC-08:00Down4/0SendNotification2011/09/2114:04:57UTC-08:00Up[RT1]日志：Sep14201120:50:34JSXZH-MC-CMNET-RT01-XAL_NE40E%%01BGP/6/SEND_NOTIFY(l):TheroutersentaNOTIFICATIONmessagetopeer211.138.205.2.(ErrorCode=4,SubErrorCode=0,BgpAddressFamily=Public,ErrorData=NULL)邻居发的报文未收到，本地感知错误，通知邻居断连时间、原因等Page11BGP五种报文类型Open：能力协商（你好？）Update：路由更新/撤销（保活、增量更新）KeepAlive：保活，19字节，华为缺省60秒；1/3个Hodtimer；Refresh：路由全部重发Notification：邻居断连Page12Page13BGP报文格式-Notification错误码1错误码子错误码错误说明1BGP报文头错误1/1Marker错误1/2报文长度错误1/3报文类型错误2Open报文错误2/1不支持的版本号（非BGP4版本）2/2PeerAS错误(与配置不符)2/3BGPidentify错误(与自己的id相同)2/4不支持的可选参数2/5鉴权失败2/6不可接受的holdtime时间2/7不支持的协商能力(RFC3392)3UPDATE报文错误0Unspecific（未使用，不可识别）3/1畸形的属性列表(报文过大)3/2不可识别的公认（well-known）属性3/3缺少公认属性3/4属性标记错误（标记与类型规定不符）3/5属性长度错误（长度与类型规定不符）3/6无效的起源属性（ORINGIN）3/7AS号环路3/8无效的下一跳（NEXT-HOP）属性3/9可选属性错误3/10无效的网络层信息3/11畸形的AS-PATH属性Page14BGP报文格式-Notification错误码2错误码子错误码错误说明HoldTime超时4/0HoldTime超时状态机错误5/0状态机错误Cease/

连接终结6/1路由前缀超限6/2管理员关闭6/3邻居重新配置6/4管理员重置连接6/5拒绝连接6/6其他配置变更6/7连接冲突6/8资源不足6/9BFD通知邻居down这两类最常见Page15BGP状态机故障终极方法-debugPage16BGP邻居关系常用命令行总结displaycurrent-configurationconfigurationbgp //配置问题占绝大部分displaybgppeerverbose //有verbose就尽量用displaybgpvpnv4allpeerdisplaybgppeerx.x.x.xlog-infoping–ax.x.x.xx.x.x.x/pingx.x.x.xdisplaytcpstatusremote-ipx.x.x.xPage17BGP公网流量中断的定位思路Page18BGP公网路由常见问题BGP路由没收到，在BGP路由表中看不到；BGP路由收到，在BGP路由表中能看到但因下一跳不活跃(valid)；BGP路由收到，在BGP路由表中活跃，但是在IP路由表中看不到；Page19Q1：BGP路由没收到？<MXEXRPI3>displaybgprou62.97.128.019<MXEXRPI3>检查配置1、相应的BGP邻居是否Established状态？displaybgppeer2、相应的BGP邻居是否发送了此路由？3、查看的路由掩码是否错误？displaybgprouting-tablex.x.x.xx.x.x.x4、检查对应地址族下的入口filter是否被deny？peerx.x.x.xroute-policy***importpeerx.x.x.xip-prefix***importpeerx.x.x.xas-path-filter***importpeerx.x.x.xfilter-policy***importpeerx.x.x.xroute-limit***Page20Q2：BGP路由收到，但在BGP路由表不活跃？[RT1]displaybgprouting-tablepeer202.112.146.100received-routesTotalNumberofRoutes:1BGPLocalrouterIDis202.112.146.1Statuscodes:*-valid,>-best,d-damped,h-history,i-internal,s-suppressed,S-StaleOrigin:i-IGP,e-EGP,?-incompleteNetworkNextHopMEDLocPrfPrefValPath/Ogn

i2.2.2.0/24100.112.146.1001500i[RT1]displayiprouting-table2.2.2.024verbose //IP路由表中没有[RT1]BGP路由不活跃Page21Q2：BGP路由收到，但在BGP路由表不活跃？[RT1]displayiprouting-table100.112.146.100verbose //没有下一跳的路由[RT1]displaybgprouting-table2.2.2.024BGPlocalrouterID:202.112.146.1LocalASnumber:100Paths:1available,0best,0selectBGProutingtableentryinformationof2.2.2.0/24:From:202.112.146.100(202.112.146.100)RouteDuration:00h05m36s

RelayIPNexthop:0.0.0.0

RelayIPOut-Interface:Originalnexthop:100.112.146.100Qosinformation:0x0AS-pathNil,originigp,localpref150,pref-val0,internal,pre255Notadvertisedtoanypeeryet迭代不到下一跳和出接口Page22Q3：BGP路由活跃，但在IP路由表中不活跃？[RT1]displaybgprouting-tablepeer202.112.146.100received-routesTotalNumberofRoutes:1BGPLocalrouterIDis202.112.146.1Statuscodes:*-valid,>-best,d-damped,h-history,i-internal,s-suppressed,S-StaleOrigin:i-IGP,e-EGP,?-incompleteNetworkNextHopMEDLocPrfPrefValPath/Ogn*>i129.1.1.0/24202.112.146.1001500I[RT1]displayiprouting-table129.1.1.0RouteFlags:R-relay,D-downloadtofibRoutingTable:PublicSummaryCount:1Destination/MaskProtoPreCostFlagsNextHopInterface129.1.1.0/24

Static600D0.0.0.0NULL0从邻居已经收到路由并活跃Page23Q3：BGP路由活跃，但在IP路由表中不活跃？[Quidway]displayiprouting-table129.1.1.024verboseRouteFlags:R-relay,D-downloadtofibRoutingTable:PublicSummaryCount:2Destination:129.1.1.0/24Protocol:StaticProcessID:0Preference:60Cost:0NextHop:0.0.0.0Neighbour:0.0.0.0State:ActiveAdvAge:00h00m34sTag:0Priority:mediumLabel:NULLQoSInfo:0x0IndirectID:0x0RelayNextHop:0.0.0.0Interface:NULL0TunnelID:0x0Flags:DDestination:129.1.1.0/24Protocol:BGPProcessID:0Preference:255Cost:0NextHop:202.112.146.100Neighbour:202.112.146.100State:InactiveAdvReliedAge:00h01m02sTag:0Priority:lowLabel:NULLQoSInfo:0x0IndirectID:0x2RelayNextHop:0.0.0.0Interface:Ethernet0/0/0TunnelID:0x0Flags:R[Quidway]优先级preferenceBGP路由不活跃Page24路由表的层级Page25BGP路由常用命令行总结BGP路由表和IP路由表详细信息同时查看，注意带掩码displayiprouting-tablex.x.x.xx.x.x.xverbose //IP路由详细信息displaybgprouting-tablex.x.x.xx.x.x.x //BGP路由详细信息displaybgprouting-tablestatistics //BGP路由总数displayiprouting-tablestatistics //IP路由总数displaybgprouting-tablepeerx.x.x.xreceived-routes//从邻居收到的路由【注意】displaybgprouting-tablepeerx.x.x.xadvertised-routes//发给邻居的路由当前版本显示的BGP路由属性是本地存储，并非是真正发送给邻居的

Page26BGP路由属性-选路规则（LAOMEN老男人）1、Preferred-value（大的优先，本地有效，不传递，Cisco叫weight）2、Local-Preference（大的优先）3、Aggregator>Automic-Aggregate4、AS-Path5、Origin6、MED7、eBGP>iBGP>LocalCross>RemoteCross8、Nexthop(cost)负载分担选择条件9、Cluster-List10、Originator-ID(Route