[c-nsp] cisco 3750 arp timeout

[Matt Bazan]

This is what I'm seeing too Robert.  If I roll the resources I'm unable
to connect to virt servers.  If I then do a 'clear arp-cache' I'm able
to connect fine.  I'll do some more investigating on the M$ side of
things to see if they've got an easier work around than the one you
mentioned.  Thanks,

  Matt 

> -----Original Message-----
> From: Robert Crowe [mailto:rocrowe at cisco.com] 
> Sent: Thursday, January 13, 2005 2:14 PM
> To: Matt Bazan; 'Church, Chuck'; cisco-nsp at puck.nether.net
> Cc: rocrowe at cisco.com
> Subject: RE: [c-nsp] cisco 3750 arp timeout
> 
>  
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Matt,
> 
>         I believe I ran into the same issue your talking about awhile
> back when I was doing systems work. Our issue was with pairs of
> servers running Win2k Advanced Server and Microsoft clustering. The
> storage was EMC. It ended up being the way Microsoft clustering sends
> the gratuitous arp. One way to tell is to failover the services and
> immediately do "clear arp" on the switches they are plugged into. We
> ended writing a script that would snmp poll the virtual address for
> the hostname of the box. When a failover occurred the hostname would
> change and the script would telnet to the 2 switches and clear the
> arp entries.
> 
> 
> - -
> Robert Crowe
> 
> 
> 
> - -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Matt Bazan
> Sent: Thursday, January 13, 2005 4:49 PM
> To: Church, Chuck; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] cisco 3750 arp timeout
> 
> Hi Chuck,
>         In this particular case I've got two 3750's in a stack and
> several MS clusters attached (one cluster node plugs into stack
> member 1, the other node into member 2) and I'm having communication
> problems reaching the cluster virtual servers when I 'roll' the
> resources over from one node in the cluster to the other.  One of my
> theories is that the stack could be having problems with the grat
> arps it's getting from the MS cluster.
> 
>         As these systems are in our data center I'll have to wait
> till the next time I'm over there to put a sniffer on the wire to see
> if I can glean more info.
> 
>         In the meantime, to attempt to rule out a grat arp issue, I
> was trying to get the ciscos to not cache the cluster's virt server
> IP and associated MAC. 
> 
>   Matt
> 
> > -----Original Message-----
> > From: Church, Chuck [mailto:cchurch at netcogov.com]
> > Sent: Thursday, January 13, 2005 1:19 PM
> > To: Matt Bazan; cisco-nsp at puck.nether.net
> > Subject: RE: [c-nsp] cisco 3750 arp timeout
> >
> > Matt,
> >
> >       On a side note, why are you trying to do this?  Rodney
> > mentioned the CEF issue.  Are you trying to speed up HSRP/VRRP or
> > something along those lines?  Just curious...
> >
> >
> > Chuck Church
> > Lead Design Engineer
> > CCIE #8776, MCNE, MCSE
> > Netco Government Services - Design & Implementation Team 1210 N.
> > Parker Rd.
> > Greenville, SC 29609
> > Home office: 864-335-9473
> > Cell: 703-819-3495
> > cchurch at netcogov.com
> > PGP key:
> > http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D 
> >
> >
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net
> > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Matt Bazan
> > Sent: Thursday, January 13, 2005 3:23 PM
> > To: cisco-nsp at puck.nether.net
> > Subject: [c-nsp] cisco 3750 arp timeout
> >
> > I've got a number of interfaces on one of my 3750's (IOS 12.1(11)AX
> > SMI) that I've set the arp timeout to be one second.  However, the
> > entries in the arp cache continue to show up until the default arp
> > timeout has been reached.  It was my understanding that setting the
> > arp timeout per interface to 1 would clear these entries after 1
> > second.  Am I misunderstanding how this command works?  If so, is
> > there a command to remove entries from the arp cache after 1
> > second?  Thanks,
> >
> >   Matt
> >
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> >
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/ 
> 
> 
> -----BEGIN PGP SIGNATURE-----
> Version: PGP 8.1
> 
> iQA/AwUBQebyks6DimsZpmH4EQJZxQCffOhvudUKeWLCX1HQnyLaZv0U22wAn3qm
> xT6jWknLf+Aoi9uV+5yN4Xrc
> =ym4x
> -----END PGP SIGNATURE-----
>  
>