[PATCH,RFC] Allow exchanging LOCAL_PREF with eBGP peers.

[Tim Weippert]

Hi Lennert, 

On Sat, Feb 18, 2017 at 05:41:07AM +0200, Lennert Buytenhek wrote:
> Hello!
> 
> I've attached a patch that allows (selectively) exchanging LOCAL_PREF
> with eBGP peers.

a perfect timing. Yesterday i thought about that ..

> The BGP RFC (RFC4271) says that you shouldn't send LOCAL_PREF to eBGP
> peers, but most modern BGP implementations have an override to allow
> doing this anyway, and it is very useful in some scenarios, for example
> if you have a network topology a la RFC7938.

[ ... ]

> I'm not submitting this patch for inclusion yet at this point (which is
> why there is no documentation), but this kind of functionality is useful
> for us, and I'd like to hear from people whether they think this could
> be useful for them, too.  And of course, there will have to be a lot of
> bikeshedding about the name of the config option! :-)

I thought about it yesterday as it could be helpfull in my situation, i
then come to the solution to use MED and/or an Community Setting which
will trigger the  LOCAL_PREF in the foreign AS (eBGP Peering). 

I think that is today a common way to do this. So i see the need but 
there exists some ways which will be more standardized within BGP!?

If i had all eBGP AS Peerings under my control, it may be usefull to do 
it directly with a LOCAL_PREF spreaded over the ASN, if not i think you 
want enable it, as the foreign AS can set it to any value it want/think. 
And you had to filter it again to not clash it with internal AS usage of
LOCAL_PREF?!

So for general implementations i think it isn't needed/usefull, but for
some special purposes it would be great to had the possibility to send
LOCAL_PREF towards eBGP borders.

just my thoughts, 
tim

-- 
Tim Weippert
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