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The Graveyard - Products No Longer Supported => D-Link NetDefend Firewalls => Topic started by: addicted on March 20, 2011, 06:13:12 AM

Title: ARP Request by DFL-800 WAN1 & WAN2
Post by: addicted on March 20, 2011, 06:13:12 AM
Dear All

I have a new issue. I have DFL-800 working with dual wan on two different ip ranges. the problem is when I tried to check what traffic WAN1 and WAN2 is sending, im amazed to see a huge traffic with ARP requests only creating network congestion. for example:

192.168.1.100 is ADSL Modem
192.168.1.6 is WAN1

3/20/2011 17:03   Who has 192.168.1.100? Tell 192.168.1.6
3/20/2011 17:03   Who has 192.168.1.100? Tell 192.168.1.6
3/20/2011 17:03   Who has 192.168.1.100? Tell 192.168.1.6
3/20/2011 17:03   Who has 192.168.1.100? Tell 192.168.1.6

192.168.0.100 is ADSL Modem
192.168.0.1 is WAN2

3/20/2011 17:04   Who has 192.168.0.100? Tell 192.168.0.1
3/20/2011 17:04   Who has 192.168.0.100? Tell 192.168.0.1
3/20/2011 17:04   Who has 192.168.0.100? Tell 192.168.0.1
3/20/2011 17:04   Who has 192.168.0.100? Tell 192.168.0.1

Please advise

Regards

Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: Ferdinent on March 21, 2011, 10:34:26 PM
Hi,

Do you see this arp requests in the log of DFL-800?

If no,

Please explain how did you capture this traffic (Network setup)?
That would be helpfull to isolate the issue... :)
Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: addicted on March 23, 2011, 12:19:51 AM
Hi
Thanks for the reply

Traffic which I captured is from a pc which is directly connected to Adsl Modem

ADSL MODEM ROUTER1-  PORT1 - Connected to a PC
                                  PORT2  - DFL-800 WAN1

ADSL MODEM ROUTER2-  PORT1 - Connected to a PC
                                  PORT2  - DFL-800 WAN2

Hope I have clarified the situation

Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: addicted on March 27, 2011, 03:17:58 AM
Dear Ferdinent

Can you help me out please as the interface is causing congestion cause wan2 is on a wireless system

please advise any solution

Regards

Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: chechito on April 05, 2011, 12:13:35 PM
strange problem

maybe a static arp mapping can solve the situation but stay on sight  of the problem, its very strange maybe an attack?
Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: addicted on April 07, 2011, 03:25:42 AM
nope. not an attack. cause i checked it out by disconnecting the wan from modem. on boot DFL-800 starts sending ARP from WAN2 to ADSL Modem.

I thought may be ADSL modem was not ack the DFL so i changed to Linksys. Still the same

Following are some details

DFL-800 WAN2 Ip is 102
ADSL Gateway is 100

Approx in one minute its sending 60 ARP requests


TIME             TYPE   SENDER IP               SENDER MAC             TARGET IP      TARGET MAC
               
14:16:18   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:19   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:20   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:21   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:22   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:23   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:24   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:25   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:26   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:27   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:28   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:29   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:30   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:31   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:32   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:33   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:34   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:35   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:36   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:37   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:38   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:39   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:40   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:41   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:42   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:43   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:44   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:45   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:46   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:47   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:48   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:49   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:50   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:51   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:52   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:53   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:54   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:55   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:56   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:57   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:58   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:16:59   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:00   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:01   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:02   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:03   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:04   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:05   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:06   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:07   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:08   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:09   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:10   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:11   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:12   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:13   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:14   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:15   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:16   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:17   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:18   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:19   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:20   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:21   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:22   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:23   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:24   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:25   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:26   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:27   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:28   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:29   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:30   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:31   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:32   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:33   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:34   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:35   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:36   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:37   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:38   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:39   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:40   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:41   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:42   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:43   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:44   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:45   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:46   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:47   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:48   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:49   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:50   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:51   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:52   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:53   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:54   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:55   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:56   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:57   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:58   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:17:59   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:00   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:01   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:02   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:03   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:04   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:05   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:06   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:07   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:08   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:09   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:10   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:11   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:12   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:13   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:14   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:15   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:16   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:17   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:18   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:19   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:20   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:21   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:22   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:23   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:24   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:25   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:26   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:27   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:28   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:29   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:30   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:31   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:32   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:33   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:34   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:35   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:36   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:37   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:38   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:39   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:40   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:41   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:42   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:43   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:44   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:45   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:46   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:47   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:48   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:49   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:50   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:51   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:52   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:53   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:54   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:55   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:56   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:57   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:58   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:18:59   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:00   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:01   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:02   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:03   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:04   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:05   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:06   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:07   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:08   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:09   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
14:19:10   request   192.168.1.102   00-13-46-3D-XX-XX   192.168.1.100   00-00-00-00-00-00
Title: Re: ARP Request by DFL-800 WAN1 & WAN2
Post by: chechito on April 12, 2011, 11:03:23 AM
check error counter on interface try to find something wrong.

If you have free interfaces try to migrate configuration to dmz interface for example to see if problem persists

Maybe a duplex speed problem??