Re: ARP , CEF and /32 route

Thanks a lot Brian.
Just simplified my situation in the question.
I have the same network in two locations , hence need to advertise the /32
to manipulate traffic and the /32 is learned from BGP .
Was wondering why router not using ARP entry as i was under the impression
that CEF adj is based on arp if available and router uses cef adj as mac
rewrite for learned destinations.

On Mon, Mar 5, 2012 at 11:48 PM, Brian Dennis <bdennis_at_ine.com> wrote:

> Of course I'm assuming you aren't doing mobile ARP which wasn't mentioned
> but even if that was the case the static route would be preferred over the
> mobile ARP route.
>
>
> --
> Brian Dennis, CCIEx5 #2210 (R&S/ISP-Dial/Security/SP/**Voice)
> bdennis_at_ine.com
>
> Internetwork Expert, Inc.
> http://www.INE.com
>
> On 03/04/2012 08:38 PM, Brian Dennis wrote:
>
>> There is no order of preference between an ARP entry and a route. ARP
>> is just a layer 3 to layer 2 mapping. CEF doesn't install ARP entries,
>> it install routes in the FIB. This is similar to Frame Relay in that a
>> Frame Relay mapping doesn't install a /32 route to the destination.
>>
>> In your case you've told the router that 192.168.0.100/32 can be reached
>> via 192.168.1.2 so why would you ever want it to route out another
>> interface? The most specific route is going to win, ARP entry or not.
>> If this wasn't the case someone could inject ARP entries to override the
>> routing table ;-) Talk about a mess.
>>
>
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Received on Thu Mar 08 2012 - 19:45:02 ART