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Is frequent ARPing normal?

Posted on 2004-08-11
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Last Modified: 2010-04-08
I have a network where clients randomly drop their internet connection behind a cisco pix 501.   Random clients randomly drop their connection for random periods of time.  I'm not sure yet if it is a switch or the firewall.   I am guessing it is the firewall..  Anyway, I am doing some arp debugging on the pix and i notice it keeps rearping the same clients.. should it be doing this?  It will arp the same clients sometimes 5-10 times in minute.. shouldnt it cache the arp and be done with it?


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Question by:Brent92663
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Author Comment

by:Brent92663
ID: 11774885
also i as an interesting symptom.. when the clients internet goes down, he can ping the pix.. but not telnet to it..
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by:grblades
ID: 11775530
Hi Brent92663,
Can you post the PIX configuration and I will have a look to see if there is anything wrong.
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by:Brent92663
ID: 11775546
im not thinking there is a config problem, but maybe instead the interface is going bad..  the config has been in place for months,, and has been fine.
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by:grblades
ID: 11775659
What is in your 'global' command on the PIX?
One common problem is if you have a range of IP addresses suppled. This uses standard NAT so if you have a renge of 20 IP addresses then 20 machines can simultaneously use the internet at any time. Adding new machines or different user behavious (running MSN for example) could mean there are more than 20 machines trying to gain access.
You normally have a mixed NAT/PAT or just a PAT setup.

The PIX should cache the ARP responses but if it stops getting a response from a machine it might decide to issue another ARP.
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Author Comment

by:Brent92663
ID: 11775894
just a normal old global (outside) 1

we use a global nat for all the clients, and static nats for the servers

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Expert Comment

by:grblades
ID: 11776479
You just have a single IP address listed and not a range?
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Author Comment

by:Brent92663
ID: 11776710
global (outside) 1 interface

so all clients inside that do not have a static nat use the globalnat of the ip address of the external interface
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Author Comment

by:Brent92663
ID: 11777803
well i found the problem.. proxyarp was enabled.. turned it off, and boom, were all good in the hood..
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by:Brent92663
ID: 11816319
Case requested closed
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