[c-nsp] Cat6500 odd arp behavior

[David Prall]

What does "show mls rate-limit usage" show for GLEAN

What does "show mls qos protocol" show for ARP

"mls qos protocol police arp" is what you want to be using to rate limit ARP
requests at L2.

This white paper goes into the hardware rate-limiters, as well as CoPP on
the 6500:
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper
_c11_553261.html 

There could still be a bug, all the above testing was done with the latest
SXH release.

David

--
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 Andrew Miehs
> Sent: Thursday, January 24, 2013 2:43 PM
> To: <Vinny_Abello at Dell.com>
> Cc: <cisco-nsp at puck.nether.net>
> Subject: Re: [c-nsp] Cat6500 odd arp behavior
> 
> There is a problem with some dell machines and 4500s - this may be the
> same issue. Try turning off PoE on the port of use the latest firmware on
the
> dell.
> 
> 
> Sent from a mobile device
> 
> On 25/01/2013, at 5:01, <Vinny_Abello at Dell.com> wrote:
> 
> > Hi all,
> >
> > I've been having a reproducible problem across multiple Catalyst 6509
> switches running the same IOS 12.2(33)SXI4a for a while now that I just
can't
> nail down.
> >
> > In many situations where the switch is configured with an SVI on VLAN to
> function as a gateway, very often I find that I am unable to communicate
> with a newly added device or assigned IP on an existing device on that
> VLAN. No amount of probing it will appear to get it to respond. However,
if I
> am on the device itself where the IP is bound and just do a simple ping
out
> to something which has to traverse the SVI IP as a gateway, as long as the
> origin of the packet is the same IP, the switch then seems to learn the
MAC
> address properly and all is happy and continues to work from that point
> forward.
> >
> > Is there something that would prevent ARP from discovering these newly
> added devices when the switch would be soliciting the network segment
> for the MAC address for a certain IP? I was leaning towards bug... or I
have
> some unintended consequence due to the CoPP policy or rate-limiters on
> these switches which are also the same.
> >
> > I have the following mls rate limiters defined:
> >
> > mls rate-limit multicast ipv4 ip-options 100 10
> > mls rate-limit unicast ip options 100 10
> > mls rate-limit unicast ip icmp redirect 100 10
> > mls rate-limit all ttl-failure 100 10
> > mls rate-limit all mtu-failure 100 10
> >
> > I have policing on arp packets in CoPP (which I think if I remember is
done
> in software anyway), but I recall completely removing this and still
having
> the same issue.
> >
> > For reference, I'm doing in CoPP:
> >
> > class-map match-all CoPP_ARP
> >  match protocol arp
> >
> > policy-map CoPP
> > ...
> >  class CoPP_ARP
> >   police 8000000
> >  ...
> >
> > Thanks for any assistance or advice!
> >
> > -Vinny
> > _______________________________________________
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