关于mplsvpn CE端不能ping通对端问题

livetony

拓扑如下：


中间为R2 R3 R4 模拟isp网络。协议包括mpls ospf bgp
R6 R7 模拟CE端。
具体配置如下：
R6：
router ospf 10
log-adjacency-changes
network 6.6.6.6 0.0.0.0 area 0
network 26.1.1.6 0.0.0.0 area 0

interface Serial1/0
ip address 26.1.1.6 255.255.255.0
serial restart-delay 0

interface Loopback0
ip address 6.6.6.6 255.255.255.0

R2 ：
ip vrf gongsia
rd 1:1   
route-target export 1:1
route-target import 1:1

mpls label range 200 299
interface Loopback0
ip address 2.2.2.2 255.255.255.0

interface Serial1/0
ip vrf forwarding gongsia
ip address 26.1.1.2 255.255.255.0
serial restart-delay 0

interface Serial1/2
ip address 23.1.1.2 255.255.255.0
mpls ip
serial restart-delay 0

router ospf 10 vrf gongsia
log-adjacency-changes
redistribute bgp 2 subnets
network 26.1.1.2 0.0.0.0 area 0
!
router ospf 1
router-id 2.2.2.2
log-adjacency-changes
network 2.2.2.2 0.0.0.0 area 0
network 23.1.1.2 0.0.0.0 area 0
!
router bgp 2
bgp router-id 2.2.2.2
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor 4.4.4.4 remote-as 4
neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
!
address-family vpnv4
  neighbor 4.4.4.4 activate
  neighbor 4.4.4.4 send-community extended
exit-address-family
!
address-family ipv4 vrf gongsia
  redistribute ospf 10 vrf gongsia
  no synchronization
exit-address-family

R3：
router ospf 1
router-id 3.3.3.3
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 0
network 23.1.1.3 0.0.0.0 area 0
network 34.1.1.3 0.0.0.0 area 0

interface Serial1/0
ip address 23.1.1.3 255.255.255.0
mpls ip
serial restart-delay 0
!
interface Serial1/1
ip address 34.1.1.3 255.255.255.0
mpls ip
serial restart-delay 0

interface Loopback0
ip address 3.3.3.3 255.255.255.0

R4：
ip vrf gongsia
rd 1:1   
route-target export 1:1
route-target import 1:1
!
no ip domain lookup
!
mpls label range 400 499

interface Loopback0
ip address 4.4.4.4 255.255.255.0

interface Serial1/0
ip address 34.1.1.4 255.255.255.0
mpls ip
serial restart-delay 0

interface Serial1/2
ip vrf forwarding gongsia
ip address 47.1.1.4 255.255.255.0
serial restart-delay 0

router ospf 10 vrf gongsia
router-id 47.1.1.4
log-adjacency-changes
redistribute bgp 4 subnets
network 47.1.1.4 0.0.0.0 area 0
!
router ospf 1
log-adjacency-changes
network 4.4.4.4 0.0.0.0 area 0
network 34.1.1.4 0.0.0.0 area 0
!
router bgp 4
bgp router-id 4.4.4.4
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 2
neighbor 2.2.2.2 ebgp-multihop 255
neighbor 2.2.2.2 update-source Loopback0
!
address-family vpnv4
  neighbor 2.2.2.2 activate
  neighbor 2.2.2.2 send-community extended
exit-address-family
!
address-family ipv4 vrf gongsia
  redistribute ospf 10 vrf gongsia
  no synchronization
exit-address-family

R7 ：
interface Loopback0
ip address 7.7.7.7 255.255.255.0

interface Serial1/0
ip address 47.1.1.7 255.255.255.0
serial restart-delay 0

router ospf 10
router-id 7.7.7.7
log-adjacency-changes
network 7.7.7.7 0.0.0.0 area 0
network 47.1.1.7 0.0.0.0 area 0


下面是一些sh命令看到的结果：
R6#sh ip route  os
     7.0.0.0/32 is subnetted, 1 subnets
O IA    7.7.7.7 [110/129] via 26.1.1.2, 02:54:49, Serial1/0
     47.0.0.0/24 is subnetted, 1 subnets
O IA    47.1.1.0 [110/65] via 26.1.1.2, 02:54:49, Serial1/0

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     34.1.1.0/24       0          Se1/2      point2point  
201    Untagged    3.3.3.3/32        0          Se1/2      point2point  
202    301         4.4.4.4/32        0          Se1/2      point2point  
203    Untagged    6.6.6.6/32[V]     0          Se1/0      point2point  
204    Aggregate   26.1.1.0/24[V]    0                                 

R2#sh ip b vpnv4 all
BGP table version is 19, 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: 1:1 (default for vrf gongsia)
*> 6.6.6.6/32       26.1.1.6                65         32768 ?
*> 7.7.7.7/32       4.4.4.4                 65             0 4 ?
*> 26.1.1.0/24      0.0.0.0                  0         32768 ?
*> 47.1.1.0/24      4.4.4.4                  0             0 4 ?

R2#sh ip rou vrf gongsia

Routing Table: gongsia
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

     6.0.0.0/32 is subnetted, 1 subnets
O       6.6.6.6 [110/65] via 26.1.1.6, 02:58:05, Serial1/0
     7.0.0.0/32 is subnetted, 1 subnets
B       7.7.7.7 [20/65] via 4.4.4.4, 02:55:43
     26.0.0.0/24 is subnetted, 1 subnets
C       26.1.1.0 is directly connected, Serial1/0
     47.0.0.0/24 is subnetted, 1 subnets
B       47.1.1.0 [20/0] via 4.4.4.4, 02:55:43

R3#sh mpls forwarding-table
Local  Outgoing    Prefix            Bytes tag  Outgoing   Next Hop   
tag    tag or VC   or Tunnel Id      switched   interface              
300    Untagged    2.2.2.2/32        28467      Se1/0      point2point  
301    Untagged    4.4.4.4/32        26437      Se1/1      point2point  

R4#sh ip rou vrf gongsia

Routing Table: gongsia
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

     6.0.0.0/32 is subnetted, 1 subnets
B       6.6.6.6 [20/65] via 2.2.2.2, 02:10:13
     7.0.0.0/32 is subnetted, 1 subnets
O       7.7.7.7 [110/65] via 47.1.1.7, 04:57:46, Serial1/2
     26.0.0.0/24 is subnetted, 1 subnets
B       26.1.1.0 [20/0] via 2.2.2.2, 02:10:13
     47.0.0.0/24 is subnetted, 1 subnets
C       47.1.1.0 is directly connected, Serial1/2

R4#sh mpls forwarding-table
Local  Outgoing    Prefix            Bytes tag  Outgoing   Next Hop   
tag    tag or VC   or Tunnel Id      switched   interface              
400    300         2.2.2.2/32        0          Se1/0      point2point  
401    Untagged    3.3.3.3/32        0          Se1/0      point2point  
402    Pop tag     23.1.1.0/24       0          Se1/0      point2point  
403    Untagged    7.7.7.7/32[V]     0          Se1/2      point2point  
404    Aggregate   47.1.1.0/24[V]    0                                 

R7#sh ip rou os
     6.0.0.0/32 is subnetted, 1 subnets
O IA    6.6.6.6 [110/129] via 47.1.1.4, 02:10:46, Serial1/0
     26.0.0.0/24 is subnetted, 1 subnets
O IA    26.1.1.0 [110/65] via 47.1.1.4, 02:10:45, Serial1/0

R7#ping 6.6.6.6 source 7.7.7.7

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:
Packet sent with a source address of 7.7.7.7
.....
Success rate is 0 percent (0/5)


R4#ping vrf gongsia 6.6.6.6

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

R4#sh ip rou vrf gongsia

Routing Table: gongsia
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

     6.0.0.0/32 is subnetted, 1 subnets
B       6.6.6.6 [20/65] via 2.2.2.2, 02:12:21
     7.0.0.0/32 is subnetted, 1 subnets
O       7.7.7.7 [110/65] via 47.1.1.7, 04:59:53, Serial1/2
     26.0.0.0/24 is subnetted, 1 subnets
B       26.1.1.0 [20/0] via 2.2.2.2, 02:12:21
     47.0.0.0/24 is subnetted, 1 subnets
C       47.1.1.0 is directly connected, Serial1/2

这边可以看到去往6.6.6.6的下一条是2.2.2.2 但是在vrf理由表里面没有去往2.2.2.2 的。我猜想问题处在这里。但是不知道怎么解决，求大神告知啊。。

qsy112233

OSPF默认环回口是32位路由，
而MPLS分发的标签是24位的路由标签
所以，标签包无法转发
解决办法：1、改成点到点，2、32位环回口

xp12138

大哥  我签到就有4鸿鹄币呢    我来顶顶你的帖子   我顶

livetony

RFC教研室规定：基于多协议BGP的VPN顶层LSP的两个端点上必须是32位。mpls的底层是ospf就必须要用32位。其他路由协议没问题。

sunnysky

使用源ping（源地址为loopback口地址），或者通告CE和PE之间的网络，直接也能ping通