From: Joe Deleonardo (JoeDeleonardo@cox.net)
Date: Sun Jul 11 2004 - 01:01:41 GMT-3
Hi Robbie
That was kind of my original question... by the way thanks Howard.
If you configure the prefix list on one end it automagically by way of the
ORF config, tells the sending router what should be sent.
It's a pretty cool feature, saving CPU cycles on both routers, the only
problem in the real world is that you have to have the eBGP peers'
cooperation.
Not a problem in the lab though. :)
Have a good one,
Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
robbie
Sent: Saturday, July 10, 2004 4:36 PM
To: ccielab@groupstudy.com
Subject: Re: BGP ORF
I'm just now reading about the wonderful world that is ORF - something
that I'm not at all familiar with. In the article mentioned, most of it
makes sense, except for how the prefix-list 'FILTER' is applied to the
ORF peering arrangement - can anyone clarify that for me? It doesn't
seem too intuitive that one would create a prefix-list that's just
automagically applied to the ORF instance in the address-family
configuration without being mentioned.
Thanks in advance,
Robbie
Howard C. Berkowitz wrote:
> At 2:30 PM -0700 7/10/04, Joe Deleonardo wrote:
>
>>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120
>>
>> limit/120st/120st11/bgpbporf.htm
>>
>> Does anyone understand what's really going on here. At first glance it
>> seems
>> like a filter would do the same job.
>>
>> When I read into it, it almost seems like a peer that wants to accept
>> limited routes from an eBGP peer sends a message that says "only send me
>> these prefixes." Otherwise, if that's not the case, I don't see the
>> benefit
>> of doing this. You might as well use a regular filter.
>>
>> Can anyone confirm my suspicions about what's going on with this feature?
>
>
> Sure. ORF causes your peer router to block routes it would otherwise
> transmit and you would reject. At the first level, this saves bandwidth
> that would be otherwise consumed by your inbound filter.
>
> When ORF is implemented widely, it lowers the overall filtering load on
> all routers, since only desired traffic will be received.
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