Windows 2008/2012 arp timeout process

Fri Nov 30 16:05:32 UTC 2012

No, but to isolate any possible layer2 traffic that could affect the issue, one of my colleagues performed host to guest testing in a VM and we are seeing the same issue.

14:28:30.420589 00:1c:42:d7:92:84 > 00:1c:42:00:00:08, ethertype ARP (0x0806), length 42: Request who-has 10.211.55.2 (00:1c:42:00:00:08) tell 10.211.55.3, length 28
14:28:30.420684 00:1c:42:00:00:08 > 00:1c:42:d7:92:84, ethertype ARP (0x0806), length 60: Reply 10.211.55.2 is-at 00:1c:42:00:00:08, length 46
14:29:03.421388 00:1c:42:d7:92:84 > 00:1c:42:00:00:08, ethertype ARP (0x0806), length 42: Request who-has 10.211.55.2 (00:1c:42:00:00:08) tell 10.211.55.3, length 28
14:29:03.421505 00:1c:42:00:00:08 > 00:1c:42:d7:92:84, ethertype ARP (0x0806), length 60: Reply 10.211.55.2 is-at 00:1c:42:00:00:08, length 46
14:29:36.423363 00:1c:42:d7:92:84 > 00:1c:42:00:00:08, ethertype ARP (0x0806), length 42: Request who-has 10.211.55.2 (00:1c:42:00:00:08) tell 10.211.55.3, length 28
14:29:36.423463 00:1c:42:00:00:08 > 00:1c:42:d7:92:84, ethertype ARP (0x0806), length 60: Reply 10.211.55.2 is-at 00:1c:42:00:00:08, length 46
14:30:09.424479 00:1c:42:d7:92:84 > 00:1c:42:00:00:08, ethertype ARP (0x0806), length 42: Request who-has 10.211.55.2 (00:1c:42:00:00:08) tell 10.211.55.3, length 28

The "real" traffic was just pings between the host/vm, and a raw capture was performed and the only mac addresses in use were the ones listed above.

________________________________
 From: Marcel Plug <marcelplug at gmail.com>
To: James Stoll <eng.jstolli at yahoo.com> 
Cc: "nanog at nanog.org" <nanog at nanog.org> 
Sent: Friday, November 30, 2012 8:35 AM
Subject: Re: Windows 2008/2012 arp timeout process

Hi James,

Is your windows client seeing traffic from the 6500 with the real (Burned in) MAC address of your 6500?  If so it may be re-arping to find out which of the MAC addresses is the 'right' one to use, the real MAC or the  HSRP MAC.

My memory is fuzzy, but I think I've seen issues like that before.  Sorry its been a while so I can't remember anything more specific.

-Marcel

On Thu, Nov 29, 2012 at 5:22 PM, James Stoll <eng.jstolli at yahoo.com> wrote:

Greetings Nanog,
>
>I apologize in advance if this should be directed towards a server/systems discussion list, but I've noticed some (what I think are) issues with the way windows 2008/2012 handles arp. I started noticing some high arp processes on some of our 6500s running sup720s, and after performing some captures of packets being punted to the cpu I found that there were quite a few repeat sources. After digging into the sources, it looks like windows 2008/2012 systems are sending arp refresh requests quite frequently.
>
>According to this article ( http://support.microsoft.com/kb/949589 ), if the neighbor entry is in use for the IP it should not go stale. Specifically:
>
>"If the entry is in the "Reachable" state, Windows Vista TCP/IP hosts do not send ARP requests to the network. Therefore, Windows Vista TCP/IP hosts use the information in the cache. If an entry is not used, and it stays in the "Reachable" state for longer than its "Reachable Time" value, the entry changes to the "Stale" state. If an entry is in the "Stale" state, the Windows Vista TCP/IP host must send an ARP request to reach that destination."
>
>I know that states Windows Vista, but the "applies to" section lists the other OSes.
>
>I've replicated this in my lab (server pinging its own gateway while capturing traffic), and I am seeing the same issue:
>
>222         10:05:18.462720                Dell_a6:dc:52     All-HSRP-routers_0a       ARP        Who has 10.36.0.1?  Tell 10.36.0.31
>223         10:05:18.464759                All-HSRP-routers_0a       Dell_a6:dc:52     ARP        10.36.0.1 is at 00:00:0c:07:ac:0a
>1886       10:06:31.962218                Dell_a6:dc:52     All-HSRP-routers_0a       ARP        Who has 10.36.0.1?  Tell 10.36.0.31
>1887       10:06:31.963004                All-HSRP-routers_0a       Dell_a6:dc:52     ARP        10.36.0.1 is at 00:00:0c:07:ac:0a
>3348       10:07:23.461682                Dell_a6:dc:52     All-HSRP-routers_0a       ARP        Who has 10.36.0.1?  Tell 10.36.0.31
>3349       10:07:23.471003                All-HSRP-routers_0a       Dell_a6:dc:52     ARP        10.36.0.1 is at 00:00:0c:07:ac:0a
>
>I've tried this on various devices, and the only place I don't see this behavior is on wireless interfaces.
>
>I'm more of a linux guy, and performing the same tests there I see the behavior stated in this article (which is what I would expect) - http://linux-ip.net/html/ether-arp.html . Specifically:
>
>"Entries in the ARP cache are periodically and automatically verified unless continually used."
>
>Has anyone run into this issue before ? Have a fix ? Point me to any documentation or other distros that I should ask ?
>
>TIA,
>James
>