实验拓扑
1：配置基本地址，以及使ISP中间运行OSPF，使两端PE可以互通。
2：内部起BGP，使用MPLS解决黑洞问题。
3：启用VRF。用来承载大量前缀以及负责路由导入导出。
4：启用扩展团体属性：××× V4，将需要做ipv4 vrf的放在一个属性内。
5：将IPv4 vrf的汇总和同步关掉。并将从CE学到的路由重分布进来。
6：将×××应用在接口，PE和CE相连的接口。注意IP地址。
7：CE端将相关路由写出来。
下边是一个简单的实验：
R5#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
S 1.1.1.0 [1/0] via 45.1.1.4
5.0.0.0/24 is subnetted, 1 subnets
C 5.5.5.0 is directly connected, Loopback10
45.0.0.0/24 is subnetted, 1 subnets
C 45.1.1.0 is directly connected, Serial1/0
R5#ping 1.1.1.1 source 5.5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 5.5.5.5
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 72/90/104 ms
router ospf 110
log-adjacency-changes
network 2.2.2.0 0.0.0.255 area 1
network 23.1.1.0 0.0.0.255 area 1
!
R2：router bgp 1
no synchronization
bgp log-neighbor-changes
neighbor 4.4.4.4 remote-as 1
neighbor 4.4.4.4 update-source Loopback10
no auto-summary
!
address-family vpnv4
neighbor 4.4.4.4 activate
neighbor 4.4.4.4 send-community both
exit-address-family
!
address-family ipv4 vrf A
redistribute static
no auto-summary
no synchronization
exit-address-family
OSPF自动将环回口作为32位主机路由通告，所以在MPLS中传递时到终点并未有32位路由，可以手工修改为24为。
RD的作用是在VRF中指出“我是谁”，用来区分路由。
RT的作用是在VRF路由中引入和送出路由。
RD的格式
RD分为两种格式：
ASN:nn（常用）和IP-address:nn
ASN代表BGP AS号码，nn代表数字，数字可以随便定义，只要合理即可，但这个数字，对于一台路由器上的不同用户，肯定是不同的。
比如一个用户的网段是10.1.1.0/24，RD是100:1，那么用户的vpnv4为100:1:10.1.1.0/24
下一个实验：
内部PE1,P,PE2运行OSPF；CE1,PE1运行EIGRP；CE2，PE2运行RIPV2。
全网使用MPLS，其他与上边相同，实现两端内部互通
CE1：router eigrp 90
network 0.0.0.0
no auto-summary
interface Serial1/1
ip address 12.1.1.1 255.255.255.0
tag-switching ip
PE1：interface Loopback10
ip address 2.2.2.2 255.255.255.0
ip ospf network point-to-point
interface Serial1/0
ip vrf forwarding A
ip address 12.1.1.2 255.255.255.0
tag-switching ip
interface Serial1/1
ip address 23.1.1.2 255.255.255.0
tag-switching ip
router eigrp 90
no auto-summary
!
address-family ipv4 vrf A
redistribute bgp 1 metric 1544 20000 255 1 1500
network 12.1.1.0 0.0.0.255
no auto-summary
autonomous-system 90
exit-address-family
router ospf 110
log-adjacency-changes
network 2.2.2.0 0.0.0.255 area 0
network 23.1.1.0 0.0.0.255 area 0
router bgp 1
no synchronization
bgp log-neighbor-changes
neighbor 4.4.4.4 remote-as 1
neighbor 4.4.4.4 update-source Loopback10
no auto-summary
address-family vpnv4
neighbor 4.4.4.4 activate
neighbor 4.4.4.4 send-community extended
exit-address-family
address-family ipv4 vrf A
redistribute eigrp 90
no auto-summary
no synchronization
exit-address-family
P：router ospf 110
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 0
interface Serial1/1
ip address 34.1.1.3 255.255.255.0
tag-switching ip
interface Serial1/0
ip address 23.1.1.3 255.255.255.0
tag-switching ip
interface Loopback10
ip address 3.3.3.3 255.255.255.0
CE2#traceroute
Protocol [ip]:
Target IP address: 1.1.1.1
Source address: 5.5.5.5
1 34.1.1.4 [MPLS: Label 19 Exp 0] 124 msec 112 msec 100 msec
2 34.1.1.3 [MPLS: Labels 16/18 Exp 0] 80 msec 104 msec 104 msec
3 12.1.1.2 [MPLS: Label 18 Exp 0] 124 msec 72 msec 96 msec
4 12.1.1.1 80 msec * 228 msec
CE1#ping 5.5.5.5 source 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 84/95/116 ms
看一下PE端的MPLS表：
PE2#show mpls forwarding-table
Local Outgoing Prefix Bytes tag Outgoing Next Hop
tag tag or VC or Tunnel Id switched interface
16 16 2.2.2.0/24 0 Se1/0 point2point
17 Untagged 3.3.3.3/32 0 Se1/0 point2point
18 Pop tag 23.1.1.0/24 0 Se1/0 point2point
19 16 1.1.1.0/24[V] 2600 Se1/0 point2point
20 16 12.1.1.0/24[V] 0 Se1/0 point2point
21 Pop tag 5.5.5.0/24[V] 3760 Se1/1 point2point
22 Aggregate 45.1.1.0/24[V] 0
