CP7920 sends ARP Req. every 60sec.

Unanswered Question
Jan 31st, 2007

Hi there,

Does anyone know, why the CP7920 send aprox. every 60 sec. an ARP Req. Packet

Src: MAC Cisco 7920

Dst: ff:ff:ff:ff:ff:ff

-------------------------------------------------------

ARP:

Sender MAC: MAC Cisco 7920

Sender IP: 0.0.0.0

Target MAC: 00:00:00:00:00:00

Target IP: IP Cisco 7920

-------------------------------------------------------

The context of my question is that on the corresponding Switch which connects the Access Point

is "arp-inspection" and "dhcp-snooping" configured and we receive log msgs like the following

nearly every minute (same interval like the ARP Req. packets)

%SW_DAI-4-DHCP_SNOOPING_DENY: 1 Invalid ARPs (Req) on Fa1/0/1, vlan 21.([0014.f2c8.67c0/0.0.0.0/0000.0000.0000/10.98.60.140/13:53:55 MET Fri Jan 26 2007])

Is there a way to get rid of the log msgs and change the arp behavior respectively ?

! Thanks in advance !

Emanuel

I have this problem too.
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migilles Wed, 01/31/2007 - 10:44

The 7920 will send ARP for its own IP address every 60 seconds for duplicate IP detection.

e.hoehn Thu, 02/01/2007 - 07:13

I thought so.

But do you know how to prevent the log messages ?

migilles Fri, 02/02/2007 - 11:48

Sounds like a bug. Can open a TAC case. Other workaround is to disable DHCP snooping, but probably not a good alternative just to disable a message.

e.hoehn Fri, 02/02/2007 - 12:12

right, it's no good workaround ;)

sure this is a bug? 'cause this MAC ((source)7920mac) and IP ((source) 0.0.0.0)) is not in the binding table so therefor the switch has to generate the msg., doesn't it ? (just thinking)

BTW: best regards from Thomas Sillaber (if you still remember him ;)

I'll try to filter these msgs somehow. have to talk to customer about the possibility. I would apreciate a shot notice, if this really is a bug or not. cheers

ksannedhi Mon, 02/05/2007 - 17:44

Just guessing, disabling "arp inspection" might be helpful.

e.hoehn Wed, 02/07/2007 - 03:58

Of course, this would solve the issue,... BUT I need this feature to be keept turned on. You wouldn't for instance disable ip routing, just 'cause you get a log msgs, would you ?

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