The Proxy ARP rules of Windows XP.
在windows系统中有如下结论：
总结：
主机不设默认网关－－－－从不向本网段外的地址arp请求，不会发生代理arp
主机设本网段其他地址为网关－－－－－－如果目的是非本网段地址，则向所设 的网关arp请求不会发生代理arp
主机将网关设为非本网段地址－－－－－－－－向外网发包时，会arp请求所设网关的mac，如果此时真网关开启代理arp，代理就会发生
主机将网关设为自己－－－－－－－－可以对任何地址（你的目的地址，不管是多少）发arp请求，如果真网关开启代理arp，代理就会发生。
1. If the default gateway is not set, XP will not send arp request, So Proxy ARP will not work
2. If the default gateway is in the same subnet. XP will only not send arp request, all the IP is sent to the dafault gateway MAC address. If the default gateway is not working, the other Proxy ARP will not working either.
3. If the default gateway is in different subnet, the Proxy ARP will work!
4. If the default gateway is the set the itself, the Proxy ARP will work!
In conclution, to make proxy arp work for xp, the default gateway must set and must set to itself or different subnet ip address. The best is to set the same ip for default gateway.
The test is done and proved on July 09, 2008. The workstation is windows XP, and the network is Cisco 3560 and 6509.
Showing posts with label Proxy ARP. Show all posts
Showing posts with label Proxy ARP. Show all posts
Wednesday, July 9, 2008
Second IP Address Makes the Problem
There is a network issue happened in my company.
One server is relocated and the administrator wanted to keep the old ip address which is 10.200.200.5. So I created a vlan 200 and assinged IP address 10.200.200.0/24. The Vlan interface ip is 10.200.200.1.
After the configuration, we server can ping all other vlans except 10.0.99.5. I have checked the ACL on all devices and found no ban. I pinged from the switch and found that: 10.0.99.5--10.200.200.1 is OK, 10.200.200.5--10.0.99.1 NOT OK.
So the problem is on the server. After login to the server, I found that the is a secondary ip address on the server's NIC. The secondary ip address is 10.0.99.9/24. After removing the secondary ip address, the communication is GOOD.
The issue is when the server sends packet to 10.0.99.0/24, the MAC address is not pointing to ther gateway. And there is no Proxy ARP on the default gateway. So the server cannot get the MAC address of any ip address of 10.0.99.0/24. This makes the problem.
In conclusion, the problem is related to ARP. The server cannot get the mac of ip.
One server is relocated and the administrator wanted to keep the old ip address which is 10.200.200.5. So I created a vlan 200 and assinged IP address 10.200.200.0/24. The Vlan interface ip is 10.200.200.1.
After the configuration, we server can ping all other vlans except 10.0.99.5. I have checked the ACL on all devices and found no ban. I pinged from the switch and found that: 10.0.99.5--10.200.200.1 is OK, 10.200.200.5--10.0.99.1 NOT OK.
So the problem is on the server. After login to the server, I found that the is a secondary ip address on the server's NIC. The secondary ip address is 10.0.99.9/24. After removing the secondary ip address, the communication is GOOD.
The issue is when the server sends packet to 10.0.99.0/24, the MAC address is not pointing to ther gateway. And there is no Proxy ARP on the default gateway. So the server cannot get the MAC address of any ip address of 10.0.99.0/24. This makes the problem.
In conclusion, the problem is related to ARP. The server cannot get the mac of ip.
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