分享会-BGP工作过程详解

BGP邻居关系详细

陈SirCCIENO.37448华为认证高级讲师BGP的5种报文类型Open：负责和对等体建立邻居关系。KeepAlive：该消息在对等体之间周期性地发送，用以维护连接。Update：该消息被用来在BGP对等体之间传递路由信息。Notification：当BGPSpeaker检测到错误的时候，就发送该消息给对等体。Route-refresh：用来通知对等体自己支持路由刷新能力。BGP报头Marker(16B)Length(2B)Type(1B)DataHeaderMessageB:ByteOPEN的报文OptionalParameters(variable)OptParamLen(1B)BGPIdentifier(4B)Version(1B)MyAutonomousSystem(2B)HoldTime(2B)DataHeaderOpenKeepAlive的报文Marker(16B)Length(2B)Type(1B)DataHeaderUpdate的报文NetworkLayerReachabilityInformation(可变长度)PathAttribute(可变长度)PathAttributeLength(2B)WithdrawnRoutesLength(2B)WithdrawnRoutes(可变长度)DataHeaderUpdateNotification

的报文Data(可变长度)ErrorCode(1B)ErrorSubCode(1B)＝＝＝＝＝＝＝＝||＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝ErrorCode错误类型123456消息头错误OPEN消息错误UPDATE消息错误保持时间超时状态机错误终止DataHeaderNotificationRoute-refresh

的报文DataHeaderRoute-refreshAFI(2B)Res.(1B)SAFI(1B）BGP邻居关系的发现RTA1.1.1.1RTB2.2.2.2TCPSYNTCPACK+SYNTCPACKBGP邻居状态机RTA1.1.1.1RTB2.2.2.2IdleTCPSYNTCPACK+SYNTCPACKConnectOpen报文OpenSentIdleConnectOpen报文OpenSentKeepalive报文OpenComfirmKeepalive报文OpenComfirmEstablishedEstablishedUpdate，Keepalive，Route-refresh，NotificationBGP邻居状态机Open-sentOpen-confirmEstablishedIdleConnect重连计时器超时TCP连接失败重连计时器超时开始其它TCP连接失败错误错误错误KeepAlive计时器超时接收到KeepAlive消息接收到正确的OPEN报文TCP连接建立TCP连接建立其它ActiveTCP连接失败KeepAlive计时器周期更新1.AS号码2.RouteridBGP邻居状态机Open-sentOpen-confirmEstablishedIdleConnect重连计时器超时TCP连接失败重连计时器超时开始其它TCP连接失败错误错误错误KeepAlive计时器超时接收到KeepAlive消息接收到正确