今天做了很久的mpls ***的hub and spoke 模型的实验，做到最后老发现，在R5上即使把bgp的路由导入到ospf的vrf a 中在ospf vrf中仍然无法看见远端***的路由，但是lsa是可达的。在hub R6中可以获取***的路由。
R5#show ip route vrf b ospf
Routing Table: b
O 192.168.3.0/24 [110/128] via 192.168.4.2, 00:01:16, Serial0/2
R5#show ip route vrf a ospf
Routing Table: a
O 192.168.4.0/24 [110/128] via 192.168.3.2, 00:01:11, Serial0/1
R5#
R5#show ip bgp ***v4 vrf a
BGP table version is 9, 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: 3:3 (default for vrf a)
*>i11.11.11.11/32 1.1.1.1 65 100 0 ?
*>i22.22.22.22/32 1.1.1.1 65 100 0 ?
*>i192.168.1.0 1.1.1.1 0 100 0 ?
*>i192.168.2.0 1.1.1.1 0 100 0 ?
R5#show ip bgp ***v4 vrf b
为空
R5#show ip ospf 3 database
OSPF Router with ID (192.168.4.1) (Process ID 3)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.3.1 192.168.3.1 1229 0x80000004 0x002852 2
192.168.4.1 192.168.4.1 1209 0x80000004 0x003246 2
192.168.4.2 192.168.4.2 1206 0x80000003 0x00DEB2 4
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
11.11.11.11 192.168.3.1 940 0x80000001 0x006B76
192.168.1.0 192.168.3.1 940 0x80000001 0x0028BB
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
22.22.22.22 192.168.3.1 925 0x80000001 0x00DA01 3489660929
192.168.2.0 192.168.3.1 925 0x80000001 0x008880 3489660929
R5#show ip ospf 2 database
OSPF Router with ID (192.168.3.1) (Process ID 2)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.3.1 192.168.3.1 1393 0x80000004 0x002852 2
192.168.4.1 192.168.4.1 1375 0x80000004 0x003246 2
192.168.4.2 192.168.4.2 1371 0x80000003 0x00DEB2 4
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
11.11.11.11 192.168.3.1 1104 0x80000001 0x006B76
192.168.1.0 192.168.3.1 1104 0x80000001 0x0028BB
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
22.22.22.22 192.168.3.1 1089 0x80000001 0x00DA01 3489660929
192.168.2.0 192.168.3.1 1089 0x80000001 0x008880 3489660929
R5#show ip route vrf a ospf
Routing Table: a
O 192.168.4.0/24 [110/128] via 192.168.3.2, 00:23:14, Serial0/1
R5#
R5#show ip route vrf a
Routing Table: a
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
22.0.0.0/32 is subnetted, 1 subnets
B 22.22.22.22 [200/65] via 1.1.1.1, 00:19:28
O 192.168.4.0/24 [110/128] via 192.168.3.2, 00:24:00, Serial0/1
11.0.0.0/32 is subnetted, 1 subnets
B 11.11.11.11 [200/65] via 1.1.1.1, 00:19:43
B 192.168.1.0/24 [200/0] via 1.1.1.1, 00:19:43
B 192.168.2.0/24 [200/0] via 1.1.1.1, 00:19:28
C 192.168.3.0/24 is directly connected, Serial0/1
后面发现是少注意了一点技术要点
由于OSPF的防环机制下游比特位和域标，需要在R6配置
这是摘自高手的解释：
支持多VRF的OSPF增加了防止路由环路的功能:如果一条路由曾被从MP-BGP往OSPF中分发的，则PE不允许该路由再从OSPF分发到MP-BGP中。有时如果某个PE与其他PE互联的P-NETWORK端口都当掉了，唯一可用的是通过某台CE连接到另外一台PE的一条×××内线路,这时就必须要在这两台PE上关闭环路检测功能，以便OSPF路由顺利传递，连通整个×××。配置命令(OSPF 进程配置模式)：capability vrf-lite