ARP PROXY solve the problem that user’s equipment did arp dispose which is fall short of standard

Publication Date:  2014-09-12 Views:  2039 Downloads:  10
Issue Description
Version: Version 5.70 (S9300 V100R003C00SPC200)
Networking:Sees the appendix
Fault Symptom: In some site they use HAIWEI’s S9300 switch to replce peer vendor’s C6509 switch. Then find that MOTOROLA’s MDG can not access different subnet’s HA server by S9300 L3 switch
MDG IP address:172.16.38.68/28,gateway:172.16.38.66
HA server address:172.16.40.161

Alarm Information
None.
Handling Process
To solve the problem we can use the ARP-PROXY identity of switch. Enable ARP-PROXY under port can solve the problem. If find that the destination IP address of ARP REQUEST massage isn’t gateway address,reply the route MAC address.
The application scene of ARP PROXY,when two host pc belong to two different network on physical layer, and IP address belong to the different subnet of a same IP network, also doesn’t configure gateway, then can use arp-proxy enable command enable route Proxy ARP function on the switch that connect the two host pcs. Through the route Proxy ARP achieve the IP address analysis between the two PCs.
Although MDG and switch have configured same mask, but because MDG do wrong ARP dispose, that lead switch didn’t reply for ARP REQUEST. This can be avoided by enable ARP PROXY.
C peer vendor’s C6509 switch default enable ARP PROXY identity,but HUAWEI’s switch default closed. when we check peer vendor’s configuration, can not find the problem.
[Quidway] interface vlanif 101
[Quidway-Vlanif101] arp-proxy enable
Root Cause
1、Check-up correlation route information. Everything is all right.
[PUB-Master]disp ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
        Destinations : 12       Routes : 12
Destination/Mask    Proto  Pre  Cost       Flags NextHop         Interface
        2.2.2.2/32  Direct 0    0            D   127.0.0.1       InLoopBack0
      127.0.0.0/8   Direct 0    0            D   127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct 0    0            D   127.0.0.1       InLoopBack0
127.255.255.255/32  Direct 0    0            D   127.0.0.1       InLoopBack0
   172.17.38.64/28  Direct 0    0            D   172.17.38.66    Vlanif101
   172.17.38.66/32  Direct 0    0            D   127.0.0.1       InLoopBack0
   172.17.38.79/32  Direct 0    0            D   127.0.0.1       InLoopBack0
  172.17.40.160/28  Static 60   0           RD   172.17.40.181   Vlanif174
  172.17.40.176/28  Direct 0    0            D   172.17.40.179   Vlanif174
  172.17.40.179/32  Direct 0    0            D   127.0.0.1       InLoopBack0
  172.17.40.191/32  Direct 0    0            D   127.0.0.1       InLoopBack0
255.255.255.255/32  Direct 0    0            D   127.0.0.1       InLoopBack0
2、Making packet capturing,find that the ARP message that send by MDG is the destination address of the send message. But in normal ARP disposal,if find destination address and host address aren’t in the same network segment, its destination IP address should be its gateway address in the ARP message. Thus,switch respond.
Suggestions
None.

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