[c-nsp] ARP oddness

[David Prall]

Are you just getting Unicast flooding because the switch doesn't know where
the destination is?

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note0918
6a00801d0808.shtml

--
http://dcp.dcptech.com


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Chuck Church
> Sent: Friday, August 19, 2011 4:24 PM
> To: NSP - Cisco
> Subject: [c-nsp] ARP oddness
> 
> Anyone,
> 
>        Researching some issues at a remote site, seeing something I
> don't
> think should happen.  A packet capture on this remote server using
> wireshark
> and focusing in on ARP is seeing all the requests (as I'd expect), but
> I'm
> also seeing unicast replies that I shouldn't.  The MAC address table on
> the
> switch I'm attached to shows only the MAC of this remote server on that
> port.  There are no SPAN sessions on the switch either.  The
> destination
> addresses aren't multicast, they're true unicast.  Yet I'm seeing all
> these
> unicasts that aren't my mac address.  Is there some function built into
> a
> Cisco switch that broadcasts these to make them act like gratuitous
> ARPs, or
> am I really seeing something that shouldn't happen?  It's on a Sup2+
> 4500,
> running 12.2(25)EWA10 (I know it's ancient, vendor owns it...)
> 
> Thanks,
> 
> Chuck
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