On Wed, 21 Feb 2001, Przemyslaw Karwasiecki wrote:
<Disclaimer> Please don't flame me if I am doing something wrong. Just tell me how to do it better. </Disclaimer>
I wouldn't do that.
The reason for doing this is simple: First /20 is in US, second /20 is in VE and I want to advertise Venezuelan part (and only this) to some local VE provider in addition to NetRail.
If I would advertise aggregated /19 to NetRail, I would receive all traffic for this multihomed /20 only from second VE provider, as more specific advertisement would be preferred in route selection process.
You are absolutely right, and we do, indeed, have several customers that fit this sort of need. One question, though, do you have a need for full transit from the second VE provider, or is it really more for a peering like relationship? If it's just that VE provider's traffic you are looking to optimize for that /20, you might consider sending the /20 to the VE provider with no-export set and sending the whole /19 to us. It would reduce the number of routes the whole internet has to see. Also, it would probably be better to send NetRail the /20 used in VE, and the whole /19 instead of 2 /20's. It's a very minor enhancement, if any at all, but people don't complain as much about smaller routes being advertised inside of larger routes as compared to obvious aggregations like 2 /20's. Not a big deal, but something to think about. Brandon Ross 404-522-5400 EVP Engineering, NetRail http://www.netrail.net AIM: BrandonNR ICQ: 2269442 Read RFC 2644!