[c-nsp] ARP requests

Łukasz Bromirski lukasz at bromirski.net
Wed Aug 19 12:23:36 EDT 2020


Did the interface had IP address assigned in the past to main interface and then changed to subinterface ones? I remember couple of nasty 7200-impacting bugs in 15.x train (so called “CEF rewrite” or “not 13.x”) that had stale IDB entries wrongly mapped to CEF structures and that could potentially result in similar behavior.

Also, can you identify if those ARP requests are valid, belonging to subinterface link space, or totally bogus? And if they happen both on the main interface and subinterface, or only on main interface?

Working with TAC would be probably best option going forward.


> On 19 Aug 2020, at 17:03, Eugene Grosbein <eugen at grosbein.net> wrote:
> 19.08.2020 21:44, Gert Doering wrote:
>> Moin,
>> On Wed, Aug 19, 2020 at 09:40:43PM +0700, Eugene Grosbein wrote:
>>> Gi3/9 of the switch is actually the port connected to router's Gi0/1.
>>> So, the question remains same.
>> Check the routes on the router.  If you have something which is pointing
>> directly to an interface ("ip route gi0/1") it will
>> generate proxy-ARP requests for all destinations covered by that route.
>> Always use interface + gateway-IP unless this is a desired property.
> I have not such routes: the command "show ip route | include 0/1$" shows nothing.
> The interface Gi0/1 does not have any IP configuration itself, only its sub-interfaces have.
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