Re: Please help in understanding.

Hey Nadeem. Both you and the RFC are sort of right : )

You are right -- you always respond to inverse arp IF you are capable. When would you not be capable? If you have not defined the DLCIs the request is coming in on somewhere.

To prove this to yourself try setting up 2 router -- one side with inverse arp on and the other off. On the side with it off, make sure you have DLCI mappings using frame maps or frame-relay int-dlci. You should see a response. Then, remove the DLCI assignments and try again. You should not see a response

To summarize you will always respond so long as you are able to no matter if inarp is turned off or on
Regards,

Joe Astorino CCIE #24347 (R&S)
Sr. Technical Instructor - IPexpert
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-----Original Message-----
From: Nadeem Rafi <nrafia_at_gmail.com>
Date: Sat, 23 Jan 2010 23:52:13
To: Petr Lapukhov<petr_at_internetworkexpert.com>; Cisco certification<ccielab_at_groupstudy.com>
Subject: Re: Please help in understanding.

Thanks Ahmad and Peter for clarifying this.

RFC 2390

"For every InARP request, the receiving station should format a proper
response using the source addresses from the request as the target addresses
of the response. If the station is unable or unwilling to reply, it ignores
the request."

According to my previous knowledge, Cisco routers when receive any inarp
requests it always reply and there is no way to stop this behavior, only
possible thing is to stop outgoing requests but not replies...

Can some one shed some light on above two ideas?

Read more:http://www.faqs.org/rfcs/rfc2390.html#ixzz0dTF8as6l

On Sat, Jan 23, 2010 at 11:35 PM, Nadeem Rafi <nrafia_at_gmail.com> wrote:

> Thnaks Ahmad and Peter :) Yes i am using INE topology and i was sure that
> there is no ARP for frame-relay. Every thing is clear now.
>
> Thanks again
>
> Nadeem Rafi
>
>
> On Sat, Jan 23, 2010 at 10:35 PM, Petr Lapukhov <
> petr_at_internetworkexpert.com> wrote:
>
>> Nadeem,
>>
>> the reason for that logging message is that BB1 runs bridged IP over
>> Frame-Relay on DLCI 401. Your interface is not configured for bridging
>> and therefore filters ARP requests from BB1 sent over DLCI 401 (I
>> assume you are using INE topology). When you enable ARP debugging you
>> will notice those messages popping occasionally as BB1 periodically
>> sends ARP requests for the IP adddress 54.1.10.6 in ethernet frames
>> bridged over DLCI 401.
>>
>> There is no ARP in the "Ethernet" sense on Frame-Relay interfaces,
>> althogh Inverse-ARP uses very similar frames structure. I would
>> recommend you going over RFC 2390 to get better understanding of
>> InverseARP functionality.
>>
>> HTH,
>> --
>> Petr Lapukhov, petr_at_INE.com
>> CCIE #16379 (R&S/Security/SP/Voice)
>>
>> Internetwork Expert, Inc.
>> http://www.INE.com
>> Toll Free: 877-224-8987
>> Outside US: 775-826-4344
>>
>> 2010/1/23 Nadeem Rafi <nrafia_at_gmail.com>:
>> > HI GS,
>> > got following error
>> >
>> > IP ARP req filtered src 54.1.10.254 0000.0ca9.0488, dst 54.1.10.6
>> > 0000.0000.0000 wrong cable, interface Serial0/0
>> >
>> > Interface s0/0 is running frame-relay on main interface and using ip map
>> > command with broadcast keyword. Just want to know is there any ARP on
>> > frame-relay interfaces? What above messages means (although it looks
>> > obvious).
>> >
>> > Any help will be appreciated.
>> >
>> > Best Regards,
>> >
>> > Nadeem Rafi
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
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Received on Sat Jan 23 2010 - 22:35:39 ART