NE40E由于IGP路径与mpls路径不一致导致MP-BGP两端CE用户之间不能互通

发布时间:  2014-12-22 浏览次数:  132 下载次数:  0
问题描述

客户反馈mp-bgp两端CE之间无法互通
处理过程
在PE上查看对应CE路由学习情况,发现在VPN实例PE1中,到达192.168.2.0/24的路由没有选择成最优的路由
<NE40E-1>display bgp vpnv4 all routing-table


BGP Local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete



Total number of routes from all PE: 3
Route Distinguisher: 100:100


      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

*>   192.168.1.0        0.0.0.0         0                     0      ?
*>   192.168.1.1/32     0.0.0.0         0                     0      ?
*>i  192.168.2.0        4.4.4.4         0          100        0      ?

VPN-Instance PE1, Router ID 1.1.1.1:

Total Number of Routes: 3
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

*>   192.168.1.0        0.0.0.0         0                     0      ?
*>   192.168.1.1/32     0.0.0.0         0                     0      ?
   i  192.168.2.0        4.4.4.4         0          100        0      ?
检查到达4.4.4.4的路由,到达4.4.4.4的路由下一跳是走NE40E-2
<NE40E-1>display ip routing-table 4.4.4.4 verbose
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1

Destination: 4.4.4.4/32
     Protocol: OSPF             Process ID: 1
   Preference: 10                     Cost: 2
      NextHop: 12.1.1.2          Neighbour: 0.0.0.0
        State: Active Adv              Age: 00h48m48s
          Tag: 0                  Priority: medium
        Label: NULL                QoSInfo: 0x0
   IndirectID: 0x0             
RelayNextHop: 0.0.0.0           Interface: GigabitEthernet0/0/1
     TunnelID: 0x0                   Flags:  D
客户需求是mpls数据要沿NE40E-1--NE40E-3--NE40E-4进行转发,并未配置NE40E-2与其它设备建立mpls邻居,检查配置后发现NE40E-3上面修改了ospf cost值导致NE40E-1路径选择走NE40E-2更优
interface GigabitEthernet0/0/1
ip address 34.1.1.3 255.255.255.0
ospf cost 100
mpls
mpls ldp
将NE40E-3上cost值修改命令删除,并在NE40E-2上将g0/0/1 cost值修改成100后问题解决
解决方案
删除NE40E-3 g0/0/1 ospf cost值修改配置
[NE40E-3-GigabitEthernet0/0/1]undo ospf cost 
在NE40E-2上修改接口g0/0/1 ospf cost值为100
[NE40E-2-GigabitEthernet0/0/1]ospf cost 100
修改配置后,PE中vpn实例学习到的路由变成最优,CE之间互访成功
<NE40E-1>display bgp vpnv4 all routing-table


BGP Local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete



Total number of routes from all PE: 3
Route Distinguisher: 100:100


      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

*>   192.168.1.0        0.0.0.0         0                     0      ?
*>   192.168.1.1/32     0.0.0.0         0                     0      ?
*>i  192.168.2.0        4.4.4.4         0          100        0      ?

VPN-Instance PE1, Router ID 1.1.1.1:

Total Number of Routes: 3
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

*>   192.168.1.0        0.0.0.0         0                     0      ?
*>   192.168.1.1/32     0.0.0.0         0                     0      ?
*>i  192.168.2.0        4.4.4.4         0          100        0      ?
建议与总结
在mpls网络中,mpls路径需要与IGP路径一致

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