08-20-2013 03:48 PM - edited 03-04-2019 08:49 PM
Hello,
I have an odd problem with an ASR1001 and a 3560G. The ASR is for some reason reporting that there is a duplicate ip address on the link between the 3560G and the ASR
ASR#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.110.1.1 - 4c00.8203.a781 ARPA GigabitEthernet0/0/1
Internet 10.110.1.2 - 4c00.8203.a781 ARPA GigabitEthernet0/0/1
interface GigabitEthernet0/0/1
description Inside Interface
ip address 10.110.1.1 255.255.255.252
no ip redirects
ip nat inside
negotiation auto
cdp enable
ip virtual-reassembly
3560G#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.110.1.1 - 4c00.8203.a781 ARPA GigabitEthernet0/2
Internet 10.110.1.2 - 00c5.4592.bcd4 ARPA GigabitEthernet0/2
interface GigabitEthernet0/2
no switchport
ip address 10.110.1.2 255.255.255.252
Doesn't matter what we do it always thinks the mac address of the adjacent device is actually itself.....very frusturating.
Any ideas?
Thanks,
Dan.
Solved! Go to Solution.
08-21-2013 12:49 AM
Hello
Try using the no-alias command on you statics nat entrys
res
Paul
Please don't forget to rate any posts that have been helpful.
Thanks.
08-20-2013 06:48 PM
Hi Dan,
Was that interface IP misconfigured before? Did you try reload the router? Does it break traffic forwarding between ASR and 3560? Can you config static ARP for the IP?
HTH,
Lei Tian
Sent from Cisco Technical Support iPhone App
08-20-2013 07:47 PM
This is a lab setup. Yes it breaks ip forwarding between the router and switch. Static arp does not help.
It's very odd, but I think it might having something to do with nat. If I configure the 3560G with a different ip (10.110.1.3) then it all works, until i configure a static outside nat entry, then the router takes and add's 10.110.1.3 as a duplicate ip address as well!
08-21-2013 04:02 AM
Hi,
Are you using neighbor IP in your NAT config? If that's case, then is expected.
HTH,
Lei Tian
Sent from Cisco Technical Support iPhone App
08-21-2013 07:28 AM
No we are not using the neighbor command.
08-21-2013 12:49 AM
Hello
Try using the no-alias command on you statics nat entrys
res
Paul
Please don't forget to rate any posts that have been helpful.
Thanks.
08-21-2013 07:29 AM
I will try this when it happens again, but it actually stopped the duplicate ip messages....for now.
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