From: robbie (robbie@packetized.org)
Date: Sat Jul 10 2004 - 20:35:45 GMT-3
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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