BGP的邻居建立
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# IGBP直连邻居建立 # neighbor 10.1.23.3 remote-as 234 的作用： # 1、与10.1.23.3：179建立TCP连接； # 2、源检测，只允许10.1.23.3建立localhost:179连接； # 3、主动发起TCP连接；被动接收TCP连接； IOU2(config-router)#neighbor 10.1.23.2 transport connection-mode ? active Actively establish the TCP session passive Passively establish the TCP session IOU2#sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.23.3 remote-as 234 IOU3#sh run | b r b router bgp 234 bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor 10.1.23.2 remote-as 234 IOU2#sh ip bgp summ BGP router identifier 2.2.2.2, local AS number 234 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 10.1.23.3 4 234 18 18 1 0 0 00:13:20 0 # 1、IDLE状态：查路由表 # 2、active delay计时器到期后开始， # a.CONNECTED状态：被动建立 # b.ACTIVE状态：主动建立 # 3、TCP三次握手 16 15.314333 10.1.23.2 10.1.23.3 TCP 48 40501→179 [SYN] Seq=0 Win=16384 Len=0 MSS=1460 17 15.317349 10.1.23.3 10.1.23.2 TCP 48 179→40501 [SYN, ACK] Seq=0 Ack=1 Win=16384 Len=0 MSS=1460 18 15.318670 10.1.23.2 10.1.23.3 TCP 44 40501→179 [ACK] Seq=1 Ack=1 Win=16384 Len=0 # 4、OPENSEND：发送 19 15.329280 10.1.23.2 10.1.23.3 BGP 101 OPEN Message 20 15.331753 10.1.23.3 10.1.23.2 TCP 44 179→40501 [ACK] Seq=1 Ack=58 Win=16327 Len=0 21 15.338059 10.1.23.3 10.1.23.2 BGP 101 OPEN Message # OPENSEND messaga的BGP协商； # a.router-id不能相同；b.AS必须相同； Frame 19: 101 bytes on wire (808 bits), 101 bytes captured (808 bits) on interface 0 Cisco HDLC Internet Protocol Version 4, Src: 10.1.23.2, Dst: 10.1.23.3 Transmission Control Protocol, Src Port: 40501, Dst Port: 179, Seq: 1, Ack: 1, Len: 57 Border Gateway Protocol - OPEN Message Marker: ffffffffffffffffffffffffffffffff Length: 57 Type: OPEN Message (1) Version: 4 My AS: 234 Hold Time: 180 BGP Identifier: 2.2.2.2 Optional Parameters Length: 28 Optional Parameters # c.协商holdtime时间较小的；keepalive时间为holdtime的1/3； IOU2(config-router)#do sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.23.3 remote-as 234 neighbor 10.1.23.3 timers 30 120 Frame 1505: 101 bytes on wire (808 bits), 101 bytes captured (808 bits) on interface 0 Cisco HDLC Internet Protocol Version 4, Src: 10.1.23.2, Dst: 10.1.23.3 Transmission Control Protocol, Src Port: 57899, Dst Port: 179, Seq: 1, Ack: 1, Len: 57 Border Gateway Protocol - OPEN Message Marker: ffffffffffffffffffffffffffffffff Length: 57 Type: OPEN Message (1) Version: 4 My AS: 234 Hold Time: 120 BGP Identifier: 2.2.2.2 Optional Parameters Length: 28 Optional Parameters # d.协商capability Border Gateway Protocol - OPEN Message Marker: ffffffffffffffffffffffffffffffff Length: 57 Type: OPEN Message (1) Version: 4 My AS: 234 Hold Time: 180 BGP Identifier: 3.3.3.3 Optional Parameters Length: 28 Optional Parameters Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 6 Capability: Multiprotocol extensions capability Type: Multiprotocol extensions capability (1) Length: 4 AFI: IPv4 (1) Reserved: 00 SAFI: Unicast (1) Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 2 Capability: Route refresh capability (Cisco) Type: Route refresh capability (Cisco) (128) Length: 0 Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 2 Capability: Route refresh capability Type: Route refresh capability (2) Length: 0 Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 2 Capability: Enhanced route refresh capability Type: Enhanced route refresh capability (70) Length: 0 Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 6 Capability: Support for 4-octet AS number capability Type: Support for 4-octet AS number capability (65) Length: 4 AS Number: 234 # BGP协商成功，则进入keepalive； # BGP协商失败，则进入notification； # IBGP非直连邻居建立 # a.节省full-mesh互联成本 # b.用Loopback口建立邻居，可以简化配置； # c.发送数据包源地址为接口地址，根据源检测，需要修改发送TCP源地址为loopback地址； # neighbor 10.1.2.2 update-source Loopback0;单向neighbor可以建立TCP连接； IOU2(config-router)#do sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.3.3 remote-as 234 neighbor 10.1.3.3 update-source Loopback0 IOU3(config-router)#do sh run | b r b router bgp 234 bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor 10.1.2.2 remote-as 234 neighbor 10.1.2.2 update-source Loopback0 # EBGP直连邻居建立 IOU2#sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.23.3 remote-as 432 IOU3#sh run | b r b router bgp 432 bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor 10.1.23.2 remote-as 234 # a.EBGP的TTL为1，建议相邻节点建立EBGP邻居； Frame 15: 48 bytes on wire (384 bits), 48 bytes captured (384 bits) on interface 0 Cisco HDLC Internet Protocol Version 4, Src: 10.1.12.1, Dst: 10.1.12.2 0100 .... = Version: 4 .... 0101 = Header Length: 20 bytes (5) Differentiated Services Field: 0xc0 (DSCP: CS6, ECN: Not-ECT) Total Length: 44 Identification: 0x84f0 (34032) Flags: 0x02 (Don't Fragment) Fragment offset: 0 Time to live: 1 Protocol: TCP (6) Header checksum: 0xc817 [validation disabled] [Header checksum status: Unverified] Source: 10.1.12.1 Destination: 10.1.12.2 [Source GeoIP: Unknown] [Destination GeoIP: Unknown] Transmission Control Protocol, Src Port: 40040, Dst Port: 179, Seq: 0, Len: 0 # EBGP非直连邻居建立 IOU2(config-router)#do sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.3.3 remote-as 432 neighbor 10.1.3.3 update-source Loopback0 IOU3(config-router)#do sh run | b r b router bgp 432 bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor 10.1.2.2 remote-as 234 neighbor 10.1.2.2 update-source Loopback0 # a.EBGP直连检测导致不发送TCP连接，无法建立非直连邻居; IOU3(config-router)# *Nov 29 02:58:51.881: BGP: 10.1.2.2 Active open failed - no route to peer, open active delayed 7168ms (35000ms max, 60% jitter # b.直连检测：路由表中是否存在直连路由；减少发送不必要的数据包开销； # c.EBGP的TTL为1，多个路由器网络无法建立邻居； IOU2(config-router)#do sh run | b r b router bgp 234 bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 10.1.4.4 remote-as 432 neighbor 10.1.4.4 ebgp-multihop 255 neighbor 10.1.4.4 disable-connected-check neighbor 10.1.4.4 update-source Loopback0 IOU4(config-router)#do sh run | b r b router bgp 432 bgp router-id 4.4.4.4 bgp log-neighbor-changes neighbor 10.1.2.2 remote-as 234 neighbor 10.1.2.2 ebgp-multihop 255 neighbor 10.1.2.2 disable-connected-check neighbor 10.1.2.2 update-source Loopback0以上是关于BGP的邻居建立的主要内容，如果未能解决你的问题，请参考以下文章