Right. Just because someone with whom you have an eBGP connection established is also a transit provider doesn't mean you have to or even want to make use of transiting into other networks across that connection.
We've done exactly this to avoid trombone routing to get to a set of customers. -----Original Message----- From: Mark Tinka <mark@tinka.africa<mailto:Mark%20Tinka%20%3cmark@tinka.africa%3e>> To: nanog@nanog.org<mailto:nanog@nanog.org> Subject: Re: Question about the use of NO_EXPORT in BGP route announcements Date: Fri, 20 Sep 2024 16:51:03 +0200 On 9/19/24 19:26, Sriram, Kotikalapudi (Fed) via NANOG wrote: I know it makes sense for an AS to announce an aggregate less-specific prefix to transit providers and peers without NO_EXPORT while announcing some more-specific prefixes (subsumed under the aggregate) with NO_EXPORT towards customer ASes. But are there good reasons when an AS might announce a prefix (route) to a transit provider with NO_EXPORT attached? The IP address space in consideration here is meant to have global reachability. An obvious use-case would be when there is on-net content or eyeballs in the transit network that you seek, but expressly require that they do not offer transit for your traffic toward their other eBGP neighbors. Mark.
