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.
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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 http://weiti.org - weiti@weiti.org GPG Fingerprint - E704 7303 6FF0 8393 ADB1 398E 67F2 94AE 5995 7DD8