No, that's not standard practice. I do this exact thing with Level 3 and have been for many many many years. Whoever is telling you this must be green. I would recommend adding the no-export community to your more specific routes if you can so as to be a good steward of the ever growing Internet IPv4 table. ________________________________________ From: Nick Olsen [nick@flhsi.com] Sent: Wednesday, August 29, 2012 2:28 PM To: nanog@nanog.org Subject: Level 3 BGP Advertisements Greetings all. In practice, We've always advertised our space all the way down to /24's but also the aggregate block (the /20 or the /21). Just so there was still reachability to our network in the event that someone made the foolish mistake of filtering lets say prefixes smaller /23... Anyways, I've always thought that was standard practice. And its never been a problem. Until we brought up peering with level 3.. I noticed that while the /24's made it out to the world. The larger counterparts (2 /21's and a /20) did not. So, I start sniffing around. Find that I do indeed see the prefixes in Level 3's looking glass but they aren't handing it off to peers. So, Naturally, I land on this being some kind of prefix filtering issue and open a ticket with Level 3. They tell me this is standard practice. And If I want to see the /20 or /21's make it out to the rest of the world, I need to stop sending the /24's. Does this sound normal? Is what I'm doing (Advertising the aggregate prefix) a good rule of thumb? Any other thoughts? Nick Olsen Network Operations (855) FLSPEED x106 ---------------------------------------------------------------------- This email message and any attachments are for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.