MPLS 解决BGP路由黑洞问题
上图我们先不做MPLS的话，R1的环回是ping不通R6的环回
但是做了MPLS之后，R1的环回居然能ping通R6的环回
原因
MPLS将不为通过BGP学习到的路由条目分发标签号；
但是在访问BGP学习的目标时，封装该目标BGP下一跳地址所在网段的标签号；
使中间未运行BGP协议的路由器，基于标签号将流量转发到BGP的下一跳处，来避免路由黑洞。
1先到2： 2查找FIB表，给去6.6.6.6 一个标签号18
show ip cef detail FIB表
show mpls forwarding-table LFIB表
在查找LFIB表 走5.5.5.5出去，欺骗了R3和R4，最后在R5弹出标签，到6.6.6.6
下面是配置
R1
interface Loopback0
ip address 1.1.1.1 255.255.255.0
interface Ethernet0/1
ip address 12.1.1.1 255.255.255.0
router bgp 1
bgp router-id 1.1.1.1
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.0
neighbor 12.1.1.2 remote-as 2
R2
interface Loopback0
ip address 2.2.2.2 255.255.255.0
interface Ethernet0/0
ip address 12.1.1.2 255.255.255.0
interface Ethernet0/1
ip address 23.1.1.1 255.255.255.0
mpls ip 开启MPLS
router eigrp 90 动态协议
network 2.0.0.0
network 23.0.0.0
router bgp 2 bgp协议
bgp router-id 2.2.2.2
bgp log-neighbor-changes
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 next-hop-self
neighbor 12.1.1.1 remote-as 1
R3
interface Loopback0
ip address 3.3.3.3 255.255.255.0
interface Ethernet0/0
ip address 23.1.1.2 255.255.255.0
mpls ip
interface Ethernet0/1
ip address 34.1.1.1 255.255.255.0
mpls ip
router eigrp 90
network 0.0.0.0
R4
interface Loopback0
ip address 4.4.4.4 255.255.255.0
interface Ethernet0/0
ip address 34.1.1.2 255.255.255.0
mpls ip
interface Ethernet0/1
ip address 45.1.1.1 255.255.255.0
mpls ip
router eigrp 90
network 0.0.0.0
R5
interface Loopback0
ip address 5.5.5.5 255.255.255.0
interface Ethernet0/0
ip address 45.1.1.2 255.255.255.0
mpls ip
interface Ethernet0/1
ip address 56.1.1.1 255.255.255.0
router eigrp 90
network 5.0.0.0
network 45.0.0.0
router bgp 2
bgp router-id 5.5.5.5
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 2
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 next-hop-self
neighbor 56.1.1.2 remote-as 3
R6
interface Loopback0
ip address 6.6.6.6 255.255.255.0
interface Ethernet0/0
ip address 56.1.1.2 255.255.255.0
router bgp 3
bgp router-id 6.6.6.6
bgp log-neighbor-changes
network 6.6.6.0 mask 255.255.255.0
neighbor 56.1.1.1 remote-as 2
大家有什么问题可以在评论里评论，我会一一回复。