Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

mean of debug arp message

Hi all,

Can someone tell me what means ?

04:10:38: IP ARP: rcvd rep src 192.168.12.2 0000.0c07.ac02, dst 192.168.12.2 Vlan300

BR,

14 REPLIES

Re: mean of debug arp message

Hi,

That's the output of "debug ip arp" I presume.

This means that host 192.168.12.2 received a response from itself. The MAC Address is HSRP virtual MAC address, is this a HSRP virtual IP address?

Regards,

Dandy

New Member

Re: mean of debug arp message

a.k.a. GARP

New Member

Re: mean of debug arp message

Hi Dandy,

yes, it's a HSRP Virtual IP, but why src=dst ?

BR,

Hall of Fame Super Silver

Re: mean of debug arp message

Mustapha

If there was debug ARP running it might be interesting and helpful to see if there was a request for the address that comes before this response. If so the details from the request may help us understand the response better.

It might also be helpful to see how this interface is configured, both its physical address and the HSRP configuration.

It would also be helpful to know if there was possibly a switch of which router was HSRP lead router at the time that this ARP was generated. In a gratuitous ARP both the source address and the destination address are the same and I wonder if that might be what we are looking at.

HTH

Rick

New Member

Re: mean of debug arp message

My guess is that debug output is not from the router sending the grat arp.

NS

New Member

Re: mean of debug arp message

Hi,

you can see the diagram for more details, the arp message is produced after pinging the "192.168.12.2" from the switch when the interface Gi0/1 is down and of course no ping reply, this ARP message does not appear when Gi0/1 is UP and i receive ping reply on the switch.

New Member

Re: mean of debug arp message

Actually, that all makes sense really. You requested an arp resolution and it broadcasted the answer back to you.

NS

New Member

Re: mean of debug arp message

Your router received a gratuitous arp message sent with that router's HSRP virtual mac to everyone on that router's SVI Vlan300.

Its basically a broadcast packet that you received that is formed like an arp reply.

NS

New Member

Re: mean of debug arp message

Did the interface just come up?

New Member

Re: mean of debug arp message

Hi,

no, this debug arp is made on a 2960 switch and from it, i am trying to ping 192.168.12.2 (HSRP VIP configured between two routers).

BR,

Re: mean of debug arp message

Hi,

I can understand TRUNK between 2 x L3 device, but I don't understand why there is a TRUNK from 2 x L3 device to 2960 Switch since you are using HSRP.

I suspect,Gi0/1 is in blocking mode that's why its down?

Regards,

Dandy

New Member

Re: mean of debug arp message

Hi,

i did it with mode ACCESS instead of TRUNK, but the problem was the same, when i make Gi0/1 to DOWN administratively, Gi0/2 does not work.

BR,

Re: mean of debug arp message

Hi,

If possible, can you post the config of 2 x L3 devices and 2960 switch?

Remove confidential info (i.e. username and password).

If there are public IP address, change the first two octets with A and B

Regards,

Dandy

New Member

Re: mean of debug arp message

We may want to re-focus here; what is the noticeable problem?

If there is a problem, was there a time when this network did not have the problem?

Is this gratuitous ARP causing any problems for certain hosts?

2562
Views
0
Helpful
14
Replies