Re: cam timer tuning

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 bpdubs 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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