Re: cam timer tuning

I did have this issue several years back with the 6500's but not a 4948, I
couldn't dig up any bug's or old documentation on it though.

Naufal,

please let us know if this works for you.

JS

On Fri, Dec 28, 2012 at 12:39 PM, Marko Milivojevic <markom_at_ipexpert.com>wrote:

> Quite right. I don't think this is the result of STP. I believe this
> is the result of "silent" hosts, or hosts that disappear from the
> network, while someone is still sending them traffic (and knows about
> their existence).
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Fri, Dec 28, 2012 at 10:24 AM, Joseph L. Brunner
> <joe_at_affirmedsystems.com> wrote:
> > No b stp is a totally different feature. The root bridge in each vlan
> keeps
> > the network in a converged state b and that includes bpdub s that keep
> > flowing ever 2 seconds to keep blocking links blocking, etc.
> >
> >
> >
> > The goal of unifying the timers is make sure no unknown unicasts flood
> your
> > network when the router has superior information it saved with its longer
> > default timers than the cam table.
> >
> >
> >
> > Is this even an issue?
> >
> >
> >
> > This is usually 1% or less of unknown unicast activity.
> >
> >
> >
> > If you have lots of unknown unicasts from stale arp timers b I would
> suspect
> > you have other issues b like a port scan or virus looking for machines
> that
> > are not up friend.
> >
> >
> >
> > From: Naufal Jamal [mailto:naufalccie_at_yahoo.in]
> > Sent: Friday, December 28, 2012 1:13 PM
> > To: Joseph L. Brunner; Marko Milivojevic
> >
> >
> > Cc: ccielab_at_groupstudy.com
> > Subject: Re: cam timer tuning
> >
> >
> >
> > If we change the arp/cam timers to 600 secs across the entire L2 domain
> ie.
> > including csw's and asw's is there any STP reconvergence that could
> happen?
> > would we see any STP outage? I dont think there should be.
> >
> >
> >
> > ________________________________
> >
> > From: Joseph L. Brunner <joe_at_affirmedsystems.com>
> > To: Naufal Jamal <naufalccie_at_yahoo.in>; Marko Milivojevic
> > <markom_at_ipexpert.com>
> > Cc: "ccielab_at_groupstudy.com" <ccielab_at_groupstudy.com>
> > Sent: Friday, 28 December 2012 11:35 PM
> > Subject: RE: cam timer tuning
> >
> >
> > You should unify all timers at 600 seconds.
> >
> > That number is usually good to me.
> >
> > thanks
> >
> > -----Original Message-----
> > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> > Naufal Jamal
> > Sent: Friday, December 28, 2012 12:43 PM
> > To: Marko Milivojevic
> > Cc: ccielab_at_groupstudy.com
> > Subject: Re: cam timer tuning
> >
> > Hi Marko,
> >
> > Nexus ----------------trunk----------4948
> > Arp timer:1500 secs
> > Arp timer: 4 hours
> > Cam timer:1800 secs Cam
> > timer: 300 secs
> >
> > I know cam timer should be greater than arp timer to avoid flood. Should
> we
> > try to make the cam timer in 4948 more than 1500 secs or make the arp
> timer
> > in nexus less than 300 (aging arp in 300 secs ?? ) Any inputs?
> > ________________________________
> > From: Marko Milivojevic
> > <markom_at_ipexpert.com>
> > To: Naufal Jamal <naufalccie_at_yahoo.in>
> > Cc:
> > "ccielab_at_groupstudy.com" <ccielab_at_groupstudy.com>
> > Sent: Friday, 28 December
> > 2012 10:29 PM
> > Subject: Re: cam timer tuning
> >
> > When I've seen this in the past,
> > it was usually discrepancy between
> > host ARP and switch MAC aging timers. Try lowering timers on your
> switches
> > to be under/same as the ARP timers on hosts and see if there are any
> > differences.
> >
> > --
> > Marko Milivojevic - CCIE #18427 (SP
> > R&S)
> > Senior CCIE Instructor - IPexpert
> >
> > On Fri, Dec 28, 2012 at 1:40 AM,
> > Naufal Jamal <naufalccie_at_yahoo.in> wrote:
> >> Hello,
> >>
> >> We have a pair of nexus
> > 7K's (without vpc) running HSRP and MSTP.
> >> They are connected to access layer
> > switches 4948's. whenever we bring up a new
> >> trunk link between Nexus 7K and
> > 4948 we see unicast flooding caused due to
> >> TCN's. I am wondering if it has
> > something to do with the difference in cam
> >> aging timer in both the
> > platforms. Nexus (1800 secs) and 4948 (300 secs). can
> >> anyone put some light
> > here please? I am thinking that changing the aging timer
> >> on nexus to 300
> > secs should help.. any thoughts?
> >>
> >> Naufal
> >>
> >>
> >> Blogs and organic groups at
> > http://www.ccie.net
> >>
> >>
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Received on Fri Dec 28 2012 - 14:48:55 ART