S5700配置下一跳为null0的路由不生效

发布时间:  2015-05-16 浏览次数:  273 下载次数:  0
问题描述

1.版本:S5700 V200R001C00SPC300

2.组网拓扑:PC1-----vlan100------S5700-----vlan101------PC2,vlanif100:10.0.110.2,PC1:10.0.110.1,vlanif101:114.112.97.1,PC2:114.112.97.5

3.故障现象:在S5700上配置ip route-static 114.112.97.5 255.255.255.255 NULL0后,在S5700上不能ping通PC2,但PC1仍然可以ping通PC2。

 

处理过程

1.故障现象确认

<MXY-Zhu>ping 114.112.97.5

  PING 114.112.97.5: 56  data bytes, press CTRL_C to break

    Request time out

    Request time out

    Request time out

    Request time out

    Request time out

 

  --- 114.112.97.5 ping statistics ---

    5 packet(s) transmitted

    0 packet(s) received

100.00% packet loss

2.查看路由条目是否配置正确

<MXY-Zhu>display ip routing-table

Route Flags: R - relay, D - download to fib

------------------------------------------------------------------------------

Routing Tables: Public

         Destinations : 21       Routes : 21      

 

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

 

        0.0.0.0/0   Static  60   0          RD   10.0.110.1      Vlanif100

     10.0.110.0/30  Direct  0    0           D   10.0.110.2      Vlanif100

     10.0.110.2/32  Direct  0    0           D   127.0.0.1       Vlanif100

   114.112.97.0/25  Direct  0    0           D   114.112.97.1    Vlanif101

   114.112.97.1/32  Direct  0    0           D   127.0.0.1       Vlanif101

   114.112.97.5/32  Static  60   0           D   0.0.0.0         NULL0

3.查看是否正确下发fib转发表项

<MXY-Zhu>display fib

Route Flags: G - Gateway Route, H - Host Route,    U - Up Route

             S - Static Route,  D - Dynamic Route, B - Black Hole Route

--------------------------------------------------------------------------------

FIB Table:

Total number of Routes : 21

 

Destination/Mask   Nexthop         Flag  TimeStamp     Interface      TunnelID

114.112.97.5/32    0.0.0.0         BHSU  t[9155842]    NULL0          0x0

4.流量统计确定数据包从交换机和PC2的互联接口转发

---------------------------------------------流量统计结果-----------------------------------------------------------------

 

<MXY-Zhu>display traffic policy statistics vlan 100 inbound

 

Vlan: 100

Traffic policy inbound: p1

Rule number: 2

Current status: OK!

---------------------------------------------------------------------

Board : 0

Item                              Packets                       Bytes

---------------------------------------------------------------------

Matched                                13                           -

  +--Passed                            13                           -

  +--Dropped                            0                           -

    +--Filter                           0                           -

+--CAR                              0                           -

<MXY-Zhu>display traffic policy statistics vlan 101 outbound

 

Vlan: 101

Traffic policy outbound: p1

Rule number: 2

Current status: OK!

---------------------------------------------------------------------

Board : 0

Item                              Packets                       Bytes

---------------------------------------------------------------------

Matched                                13                           -

  +--Passed                            13                           -

  +--Dropped                            0                           -

    +--Filter                           0                           -

    +--CAR                              0                           -

---------------------------------------------流量统计结果-----------------------------------------------------------------

5.查看ARP表

发现S5700上有一条PC2的ARP表项还未过期,清除掉该表项后,PC1再无法ping通PC2。

 

 

 

根因
对于过路转发的报文,S5700上ARP表项(即32位主机路由)优先于ip路由表或fib表指导报文转发(仅V200R001C00SPC300版本)。
解决方案

在S5700上执行reset arp all,手动清除ARP表项,或等待ARP表项过期。

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