BGP基础知识及配置详情

BGP理论概述

1.传输协议：TCP 端口号179
2.BGP是外部路由协议，用来在AS之间传递路由信息
3.是一种增强的路径矢量路由协议
4.拥有可靠的路由更新机制
5.具备丰富的metric度量方法
6.无环路协议设计

1. List item

7.为路由条目附带多种属性信息
8.丰富的路由过滤和路由策略
9.无需周期性更新
10.路由更新时只发送增量路由
11.周期性发送keepAlive报文以保持TCP连通性

对等体交互原则

1.从IBGP对等体获取的BGP路由，BGP设备只传给它的EBGP对等体
2.从EBGP对等体获得的BGP路由，BGP设备传递给它所有的EBGP IBGP对等体
3.当存在多条到同一目的的地址的有效路由的时，BGP设备只将最优路由发布给对等体
4.路由更新时，BGP设备只发送更新的BGP路由
5.所有对等体发送的路由，BGP都会接收
6.所有EBGP对等体在传输的过程中下一跳改变
7.所有IBGP对等体在传输过程中下一跳不变
8.默认EBGP传递时TTL值为1
9.默认IBGP传递时TTL值为255

配置详情

1.所有设备必打命令R1为例

undo terminal monitor ——关闭弹屏
Info: Current terminal monitor is off.
sys
r1]user-interface console 0
[r1-ui-console0]id
[r1-ui-console0]idle-timeout 0 0——启用永不超时
[r1-ui-console0]quit

端口配置
R1
[r1]int g0/0/0——进入接口
[r1-GigabitEthernet0/0/0]ip add 12.1.1.1 24——配置地址
[r1-GigabitEthernet0/0/0]undo shutdown
Info: Interface GigabitEthernet0/0/0 is not shutdown.
[r1-GigabitEthernet0/0/0]int g0/0/1
[r1-GigabitEthernet0/0/1]ip add 13.1.1.1 24
[r1-GigabitEthernet0/0/1]undo shutdown
Info: Interface GigabitEthernet0/0/1 is not shutdown.
[r1-GigabitEthernet0/0/1]int loop0
[r1-LoopBack0]ip add 1.1.1.1 32
[r1-LoopBack0]quit

R2——————注意.R2.R3,R4是同一区域需要OSPF
[r2]int g0/0/0
[r2-GigabitEthernet0/0/0]ip add 12.1.1.2 24
[r2-GigabitEthernet0/0/0]undo shutdown
Info: Interface GigabitEthernet0/0/0 is not shutdown.
[r2-GigabitEthernet0/0/0]int g0/0/1
[r2-GigabitEthernet0/0/1]ip add 24.1.1.2 24
[r2-GigabitEthernet0/0/1]int loop0
[r2-LoopBack0]ip add 2.2.2.2 32
[r2-LoopBack0]int g0/0/1
[r2-GigabitEthernet0/0/1]undo shutdown
Info: Interface GigabitEthernet0/0/1 is not shutdown.
[r2-GigabitEthernet0/0/1]quit
[r2]ospf——进入
[r2-ospf-1]are
[r2-ospf-1]area 0——区域
[r2-ospf-1-area-0.0.0.0]ne
[r2-ospf-1-area-0.0.0.0]network 2.2.2.2 0.0.0.0——宣告自身网段
[r2-ospf-1-area-0.0.0.0]nr
[r2-ospf-1-area-0.0.0.0]ne
[r2-ospf-1-area-0.0.0.0]network 24.1.1.0 0.0.0.255
[r2-ospf-1-area-0.0.0.0]

R3
int g0/0/0
[r3-GigabitEthernet0/0/0]ip add 13.1.1.3 24
[r3-GigabitEthernet0/0/0]undo shutdown
Info: Interface GigabitEthernet0/0/0 is not shutdown.
[r3-GigabitEthernet0/0/0]int g0/0/1
[r3-GigabitEthernet0/0/1]ip add 34.1.1.3 24
[r3-GigabitEthernet0/0/1]undo shutdown
Info: Interface GigabitEthernet0/0/1 is not shutdown.
[r3-GigabitEthernet0/0/1]int loop0
[r3-LoopBack0]ip add 3.3.3.3 32
[r3-LoopBack0]quit
[r3]ospf
[r3-ospf-1]are
[r3-ospf-1]area 0
[r3-ospf-1-area-0.0.0.0]ne
[r3-ospf-1-area-0.0.0.0]network 3.3.3.3 0.0.0.0
[r3-ospf-1-area-0.0.0.0]ne
[r3-ospf-1-area-0.0.0.0]network 34.1.1.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]quit

R4

[r4]int g0/0/0
[r4-GigabitEthernet0/0/0]ip add 24.1.1.4 24
[r4-GigabitEthernet0/0/0]undo shutdown
Info: Interface GigabitEthernet0/0/0 is not shutdown.
[r4-GigabitEthernet0/0/0]int g0/0/1
[r4-GigabitEthernet0/0/1]ip add 34.1.1.4 24
[r4-GigabitEthernet0/0/1]undo shutdown
Info: Interface GigabitEthernet0/0/1 is not shutdown.
[r4-GigabitEthernet0/0/1]int loop0
[r4-LoopBack0]ip add 4.4.4.4 32
[r4-LoopBack0]quit
[r4]ospf
[r4-ospf-1]ar
[r4-ospf-1]area 0
[r4-ospf-1-area-0.0.0.0]ne
[r4-ospf-1-area-0.0.0.0]network 4.4.4.4 0.0.0.0
[r4-ospf-1-area-0.0.0.0]ne
[r4-ospf-1-area-0.0.0.0]network 34.1.1.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]ne
[r4-ospf-1-area-0.0.0.0]network 24.1.1.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]quit
[r4-ospf-1]quit

建立邻居关系——以上命令基础上

R1

[r1]bgp 100——进入BGP
[r1-bgp]router-id 1.1.1.1——配置地址
[r1-bgp]peer 2.2.2.2 as-number 200 ——建立邻居
[r1-bgp]peer 2.2.2.2 connect-interface LoopBack 0——环回口建立
[r1-bgp]peer 2.2.2.2 ebgp-max-hop 255——更改跳数EBGP默认一跳
[r1-bgp]peer 3.3.3.3 as-number 200
[r1-bgp]peer 3.3.3.3 connect-interface LoopBack 0
[r1-bgp]peer 3.3.3.3 ebgp-max-hop 255
[r1]ip route-static 2.2.2.2 32 12.1.1.2——EBGP需要静态路由学习对等体
[r1]ip route-static 3.3.3.3 32 13.1.1.3
[r1]bgp 100
[r1-bgp]network 1.1.1.1 32——宣告本身网段及对等体环回地址
[r1-bgp]network 2.2.2.2 32
[r1-bgp]network 3.3.3.3 32
[r1-bgp]network 13.1.1.0 24
[r1-bgp]network 12.1.1.0 24

R2

[r2]bgp 200
[r2-bgp]router-id 2.2.2.2
[r2-bgp]peer 1.1.1.1 as-number 100
[r2-bgp]peer 1.1.1.1 connect-interface LoopBack 0
[r2-bgp]peer 1.1.1.1 ebgp-max-hop 255
[r2-bgp]peer 3.3.3.3 as-number 200
[r2-bgp]peer 3.3.3.3 connect-interface LoopBack 0
[r2-bgp]peer 3.3.3.3 next-hop-local
[r2-bgp]peer 4.4.4.4 as-number 200
[r2-bgp]peer 4.4.4.4 connect-interface LoopBack 0
[r2-bgp]peer 4.4.4.4 next-hop-local
[r2-bgp]
[r2-bgp]network 2.2.2.2 32
[r2-bgp]network 1.1.1.1 32
Info: The network does not exist.
[r2-bgp]quit
[r2]ip route-static 1.1.1.1 32 12.1.1.1
[r2]bgp 200
[r2-bgp]network 1.1.1.1 32
bgp]network 2.2.2.2 32
[r2-bgp]network 3.3.3.3 32
[r2-bgp]network 24.1.1.0 24
[r2-bgp]network 12.1.1.0 24
[r2-bgp]quit

R3
[r3]bgp 200
[r3-bgp]router
[r3-bgp]router-id 3.3.3.3
[r3-bgp]peer 2.2.2.2 as
[r3-bgp]peer 2.2.2.2 as-number 200
[r3-bgp]peer 2.2.2.2 connect-interface LoopBack 0
[r3-bgp]peer 2.2.2.2 next-hop-local
[r3-bgp]peer 4.4.4.4 as-number 200
[r3-bgp]peer 4.4.4.4 connect-interface l
[r3-bgp]peer 4.4.4.4 connect-interface LoopBack 0
[r3-bgp]peer 4.4.4.4 next-hop-local
[r3-bgp]peer 1.1.1.1 as-number 100
[r3-bgp]peer 1.1.1.1 connect-interface LoopBack 0
[r3-bgp]peer 1.1.1.1 ebgp-max-hop 255
[r3-bgp]network 1.1.1.1 32
[r3-bgp]network 13.1.1.0 24
[r3-bgp]network 4.4.4.4 32
[r3-bgp]network 34.1.1.0 24
[r3-bgp]quit

R4
[r4]bgp 200
[r4-bgp]router-id 4.4.4.4
r4-bgp]peer 3.3.3.3 as-number 200
[r4-bgp]peer 3.3.3.3 connect-interface LoopBack 0
[r4-bgp]peer 2.2.2.2 as-number 200
[r4-bgp]peer 2.2.2.2 connect-interface LoopBack 0
r4-bgp]network 4.4.4.4 32
[r4-bgp]network 3.3.3.3 32
[r4-bgp]network 2.2.2.2 32
[r4-bgp]network 24.1.1.0 24
[r4-bgp]network 34.1.1.0 24
[r4-bgp]quit