05-10-2006 01:16 AM - edited 03-03-2019 03:09 AM
Hello,
i have two cisco routers, which are connected to one switch. On this switch, there are several servers connected as well.
When i connected the second cisco router, i got messages on the first router, that there is an ip address conflict. After a few minutes it seems as if the vpn tunnel on the first router breaks down because of this conflict. I'm not sure about this, but when i disconnected the second router again, the vpn tunnel could be established again. The vpn tunnel goes to another router via WAN and ends in the local class-c network, where both routers are in.
Router1
LAN 192.168.105.254 (255.255.255.0)
WAN 212.xxx.xxx.xxx
||
||
\/
Cisco Switch
/\
||
||
Router2
LAN IP 192.168.105.253 (255.255.255.0)
WAN IP 217.xxx.xxx.xxx
Router1
int fa 0/1
ip address 192.168.105.254 255.255.255.0
Router2
int fa 0/1
ip address 192.168.105.253 255.255.255.0
Could the /24 mask on the interfaces cause the conflicts?
From the servers, none has the ip 192.168.105.253 or 192.168.105.254 and if i disconnect Router2, the IP 192.168.105.253 is not reachable from any system on the switch.
So how does this ip address conflict occur?
05-10-2006 01:31 AM
Hi Friend,
You can very well have same subnet on 2 different routers so it is not a problem.
Can you confirm if on remote end where VPN tunnel is terminating if any system has an ip 192.168.105.253 255.255.255.0.
Regards,
Ankur
05-10-2006 04:03 AM
Hello Ankur,
thanks for your answer.
On the remote ends of the vpn tunnels are no local networks with 192.168.105.0/24.
I changed the ip of the second router to 192.168.105.252 ... 251 and 250, all unused so far. But the error messages still occured.
This evening i will try again.
Regards,
chasm
05-10-2006 01:37 AM
hello,
can you check the router 1 log. with error message you should have a mac address
May 10 05:32:20.489: %IP-4-DUPADDR: Duplicate address 10.10.10.1 on GigabitEthernet0/1.1, sourced by 0003.oc12.a2c3
This should help you to identify host already with 192.168.105.253.
Before connecting Router 2, from Router 1 ping 192.168.105.253 and do a sh arp ?
HTH,
regards,
cisand
05-10-2006 04:04 AM
Hello Cisand,
i will do this this evening. Tomorrow i will post the logging messages and the sh arp result.
Thanks for your answer
chasm
05-10-2006 10:42 PM
This time, no duplicate ip error messages occured.
I dont know what was the issue last time.
But this time i got another problem, but i will do a new conversation for it, because it is not related to the issue of this conversation.
Thanks for your help
chasm
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