实验拓扑：
第一步：建立VRF
R2/R4:
ip vrf *** 命名vrf为“***”
rd 100:1 设置RD
route-target export 100:1设置出口路由标记
route-target import 100:1设置入口路由标记 注：一端的出口标记和对端的入口标记需一致！
第二步：将CE接口设置成vrf转发
R2：
interface FastEthernet0/1
ip vrf forwarding ***
ip address 12.1.1.2 255.255.255.0
R4：
interface FastEthernet0/0
ip vrf forwarding ***
ip address 45.1.1.4 255.255.255.0
注意：在配置完 “ ip vrf forwarding ***”后，接口上原先配置的ip地址会消失，需重新配置。
第三步：配置mpls域的igp
R2：
router eigrp 10
network 2.2.2.2 0.0.0.0
network 23.1.1.2 0.0.0.0
no auto-summary
eigrp router-id 2.2.2.2
R3：
router eigrp 10
network 3.3.3.3 0.0.0.0
network 23.1.1.3 0.0.0.0
network 34.1.1.3 0.0.0.0
no auto-summary
eigrp router-id 3.3.3.3
!
R4：
router eigrp 10
network 4.4.4.4 0.0.0.0
network 34.1.1.4 0.0.0.0
no auto-summary
eigrp router-id 4.4.4.4
配置IGP的目的是为了是mpls域内路由互通，为配置MP-BGP做准备
第四步：配置mpbgp：
R2：
router bgp 100
bgp router-id 2.2.2.2
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 update-source Loopback0
!
address-family ***v4 配置***v4地址簇，与p路由器建立***v4邻居
neighbor 3.3.3.3 activate
neighbor 3.3.3.3 send-community both 配置扩展团体属性的发送包括了route-tag，***标签等信息
exit-address-family
!
address-family ipv4 vrf *** 配置vrf地址簇，将CE点的路由协议重分发进mpbgp
redistribute eigrp 100
no synchronization
exit-address-family
R3：
router bgp 100
bgp router-id 3.3.3.3
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 update-source Loopback0
neighbor 4.4.4.4 remote-as 100
neighbor 4.4.4.4 update-source Loopback0
!
address-family ***v4 配置***v4邻居的反射，解决iGP水平分割问题，也可以不配反射，以R2-4建立全互联邻居关系代替
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community both
neighbor 2.2.2.2 route-reflector-client
neighbor 4.4.4.4 activate
neighbor 4.4.4.4 send-community both
neighbor 4.4.4.4 route-reflector-client
exit-address-family
R4：
router bgp 100
bgp router-id 4.4.4.4
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 update-source Loopback0
!
address-family ***v4
neighbor 3.3.3.3 activate
neighbor 3.3.3.3 send-community both
exit-address-family
!
address-family ipv4 vrf ***
redistribute ospf 1 vrf *** match internal external 1 external 2 重分发ospf时注意匹配范围（inter or external）
no synchronization
exit-address-family
第五步：配置site端的路由
site1：
R2：
router eigrp 100
no auto-summary
!
address-family ipv4 vrf *** 指定vrf地址簇的配置
redistribute bgp 100 metric 10000 100 255 1 1500 将mpbgp路由重 分发进CE端
network 12.1.1.2 0.0.0.0
no auto-summary
autonomous-system 100 通告自治系统号（必须配置！）
exit-address-family
!
R1：
router eigrp 100
network 1.1.1.1 0.0.0.0
network 12.1.1.1 0.0.0.0
no auto-summary
eigrp router-id 1.1.1.1
!
site2：
R4：
router ospf 1 vrf *** ospf不能在进程下配置ipv4vrf地址簇，需在起进程时配置！
router-id 4.4.4.4
log-adjacency-changes
redistribute bgp 100 metric-type 1 subnets 将mpbgp路由充分发进ce端
network 45.1.1.4 0.0.0.0 area 0
R5：
router ospf 1
router-id 5.5.5.5
log-adjacency-changes
network 5.5.5.5 0.0.0.0 area 0
network 45.1.1.5 0.0.0.0 area 0
!
第六步：配置mpls转发
R2/R3/R4
全局：
ip cef 开启cef转发，一定要配置！！
mpls label range x00 x99 指定本地标签的分配范围，以便于管理， 也可由系统自动分配
mpls label protocol ldp cisco路由器默认标签分配协议为tdp，这里改为ldp协议
mpls ip 使路由器支持mpls 转发 默认已配置
mpls ldp router-id Loopback0 force 设置标签分配的源端口
接口下（PE和p端的接口）
mpls ip 在接口上启用mpls
现象：
1.查看R1的路由表：
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
5.0.0.0/32 is subnetted, 1 subnets
D EX 5.5.5.5 [170/307200] via 12.1.1.2, 01:09:39, FastEthernet0/1
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, FastEthernet0/1
45.0.0.0/24 is subnetted, 1 subnets
D EX 45.1.1.0 [170/307200] via 12.1.1.2, 01:09:39, FastEthernet0/1
查看R5的路由表：
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O E1 1.1.1.1 [110/409610] via 45.1.1.4, 01:10:11, FastEthernet0/0
5.0.0.0/32 is subnetted, 1 subnets
C 5.5.5.5 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
O E1 12.1.1.0 [110/11] via 45.1.1.4, 01:10:10, FastEthernet0/0
45.0.0.0/24 is subnetted, 1 subnets
C 45.1.1.0 is directly connected, FastEthernet0/0
查看R2的vrf路由表：
show ip vrf *** route :
1.0.0.0/32 is subnetted, 1 subnets
D 1.1.1.1 [90/409600] via 12.1.1.1, 01:14:33, FastEthernet0/1
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [200/11] via 4.4.4.4, 01:13:04
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, FastEthernet0/1
45.0.0.0/24 is subnetted, 1 subnets
B 45.1.1.0 [200/0] via 4.4.4.4, 01:13:04
R2的bgp ***v4表：
R2#sh ip bgp ***v4 all
BGP table version is 9, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 100:1 (default for vrf ***)
*> 1.1.1.1/32 12.1.1.1 409600 32768 ?
*>i5.5.5.5/32 4.4.4.4 11 100 0 ?
*> 12.1.1.0/24 0.0.0.0 0 32768 ?
*>i45.1.1.0/24 4.4.4.4 0 100 0 ?
R2的mpls转发表
R2#sh mpls forwarding-table
Local Outgoing Prefix Bytes tag Outgoing Next Hop
tag tag or VC or Tunnel Id switched interface
200 Pop tag 3.3.3.3/32 0 Fa0/0 23.1.1.3
201 Pop tag 34.1.1.0/24 0 Fa0/0 23.1.1.3
203 Untagged 1.1.1.1/32[V] 0 Fa0/1 12.1.1.1
204 Aggregate 12.1.1.0/24[V] 1164
205 302 4.4.4.4/32 0 Fa0/0 23.1.1.3
R3（p路由器）的***v4 bgp表：
R3#sh ip bgp ***v4 all
BGP table version is 5, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 100:1
*>i1.1.1.1/32 2.2.2.2 409600 100 0 ?
*>i5.5.5.5/32 4.4.4.4 11 100 0 ?
*>i12.1.1.0/24 2.2.2.2 0 100 0 ?
*>i45.1.1.0/24 4.4.4.4 0 100 0 ?
R4的各表略
R4前往R1：
R4#traceroute vrf *** 1.1.1.1
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 34.1.1.3 [MPLS: Labels 300/203 Exp 0] 132 msec 180 msec 188 msec
2 12.1.1.2 [MPLS: Label 203 Exp 0] 100 msec 112 msec 84 msec
3 12.1.1.1 128 msec * 124 msec
可以看到，从R2发出的包带有双层标签 内层为203 外层为300；其中203为R2为1.1.1.1的路由分配的***v4标签，300为R3分配的普通mpls标签 而当报文到达R3时，因为“次末跳弹出机制（PHP）”报文将弹出上层标签（普通mpls标签300），到达R2后就剩下了***v4标签（203），此时再根据***v4标签查找标签转发表 发现出口无标签，于是直接以ip报文形式传给了R1。